The NAV conference, organized by “Associazione Italiana di Tecnica Navale”, is the major Italian scientific event on marine technology issues. The last edition was held in Trieste in 2018 and, after the postponing of 2022 due to COVID-19, we are now organising the new edition. The NAV 2022 conference will take place in three days, covering the whole spectrum of maritime technology themes, with particular attention to new methods for the use of the sea as a source of energy and resources. About 200 papers are expected which will be shown in parallel sessions and in conjunction with specific workshops. The NAV 2022 conference will take place in Genoa, with the aim of highlighting the scientific, technological and industrial world. For this purpose, a Committee of Honor with the personalities of excellence of the International maritime cluster has been set up, giving them the role of “ambassadors” of the conference.
Skin, external surface, coating… Those are words strictly linked to the concept of appearance, which means to be watched, to show, and sometimes to seem: a comparison between to be and appear.
From a design point of view, the surface coating is, mainly, an esthetical choice. Nevertheless, sometimes that element met other reasons. During the First World War, painting warships with the dazzle technique allowed them to "hide" from the enemy: the shapes and colours applied to the hulls allowed them to appear in different sizes or positions compared to the real one. In that case, the skin assumed a vital defensive role.
Even if the large part of yachts today does not shine for peculiar external surface – if we closed the eyes we would imagine hulls in neutral colours, generally in one or two tones – skin is a project element of high potential.
Ivana Porfiri called Jeff Koons, acclaimed contemporary artist, to finish the external coat of the Guilty. The skin highlights shapes and formal choices of hull and superstructure, and also brings the bond between art and yacht design, explicit by the art exposition in the interiors, forward.
Another example of designed skin is LAP-1 by Francesco Paszkowski Design. Here the external coating was designed with camouflage with shades of blue, a symbolic colour for Baglietto shipyard, by which the yacht was built.
Finally, browsing the most significant projects, the paper aims to analyse the design and use of yachts' external coatings. The project of the skin in a nautical context is today linked to mainly esthetical reasons. Nevertheless, also thanks to the use of new materials, innovative painting, and covering techniques, we foresee new possibilities for skin design. External coat, colours, textures, and hull finishing could meet different and new needs as the energy and environmental issues.
In the last years, the leisure vessels market had a very positive trend and, every year, more and more ships will be present in our waters. This is giving a push to the demand and needs of increased security, in the protection against theft, and safety, in the protection against losing the mooring while anchored with the risk of having accidents against rocks or other vessels. The ARGOS Solution is offering the capabilities and performance to answer those needs with easy plug-in installation of a device in the boat.
The ARGOS Solution is under development in the frame of the ARGOS (Anti-theft Robust Galileo-based Operational System) project co-funded by the EU Agency for the Space Programme (EUSPA) within its Fundamental Elements funding programme.
The ARGOS Solution, leveraging the services provided by Galileo and thanks to its scalable and modular architecture, provides timely alerts in case of theft or risk of losing the mooring of the anchor point. It also provides high robustness against environmental conditions, e.g. multipath, shadowing of the GNSS signals, etc…, and external factors that can be unintentional (e.g. interference sources) or intentional (e.g. jamming or spoofing attacks in order to support a theft attempt).
These differentiating capabilities are based on the new features of Galileo, the European GNSS system, specifically the Open Service Navigation Message Authentication (OSNMA) that will increase the robustness against certain types of spoofing attacks, and the I/NAV Message improvement that will increase the performance of the GNSS signal processing in harsh environments (e.g. ports, natural harbours, etc…).
These capabilities are integrated in the solution and improved with Artificial Intelligence techniques implemented in the on-board device by fusing the GNSS information with data from other on-board sensors like Inertial Measurement Unit, anemometer, temperature/humidity/pressure sensors, etc…., in order to provide timely alerts with high performance detection of risky conditions.
The port of Sines has invested in the modernization and stimulation of its maritime sector. To this end, it has made investments directed at scientific research and risk management associated with new uses of the sea, which include the BlueSafePort project. This project aims to develop a system (on web and mobile platforms) for forecasting and warning, 72 hours in advance, of emergency situations related to navigation, docking and mooring maneuvers in port areas.
The safety system, called SAFEPORT, consists of an integrated tool that includes: the software package SWAMS – Simulation of Wave Action on Moored Ships, Pinheiro et al. 2016; numerical models to evaluate the behavior of maneuvering ships, developed by the Centre for Marine Technology and Ocean Engineering (not included in this work); a continuous monitoring procedure to evaluate and validate the results obtained by the numerical models; and a risk assessment methodology.
This work presents the results of two different simulations made for ships berthed at terminals in the port of Sines, to illustrate the system’s working. The first corresponds to a current situation, where it is not expected the system to issue an alert, and the other is a storm situation, when the forces on the mooring system may exceed pre-set limits.
References:
Pinheiro, L.; Fortes, C.J.E.M.; Santos, J.A. Rosa-Santos, P. (2016) - Numerical simulation of the motions and forces of a moored ship in Leixões harbour. MARTECH 2016 - 3rd International Conference on Maritime Technology and Engineering, 4 - 6 julho. 217-223pp. Lisboa. ISBN 978-1-138-03000-8.
The size and level of complexity of contemporary passenger ships are evolving in an ever increasing and ever faster way. Logistics and the possibility of allowing one to orient oneself independently, therefore, must deal with increasingly complex issues to be managed especially in terms of communication.
If, on one hand, it is necessary to provide all the information regarding the safeguards and useful practices in case of emergency, on the other hand, a communication system must be structured in order to guarantee not only a development of life on board as smooth as possible, but also a positive perception of the level of assistance.
Today Visual languages and new technologies can, through their integration, offer new possibilities for optimizing these design themes.
The work presented here reports the research developed by the authors starting from considerations of the state of the art to arrive at hypothetical methodological formulas and experimental applications to be implemented.
The first phase of the study focused on a series of logistic and sociological researches (also through an interview campaign) in order to identify the criticalities and potentialities of the communication systems currently active. The second phase defined a study methodology in order to identify areas of action and respective languages to be adopted. Finally, the possibilities of integration among new technologies for the development of 'on demand' visual languages were evaluated considering that these that can, in a transversal manner, fill and systematize a plurality of needs.
The advent of the pandemic in the last two years has called into question the communication apparatus referred to the identities of the shipping companies: not only this must respond to the needs of marketing and identification of those who are to be considered real brands, but today it must respond to the need for 'reassurance' regarding a new aspect, perhaps less considered before, namely that of 'health and hygiene' safety. Forms of innovation introduced in recent years, such as those entrusted to touch screens, seemed difficult to pursue and therefore paper forms ad personam, app and social media, are perhaps more effective, highlighting a progression of targets that are gradually younger.
Many media have been involved in this process and consequently the languages adopted have diversified according to different needs.
The research work presented here intends to illustrate a study methodology that starts from the assumptions of visual and linguistic analysis of the state of the art to arrive at defining reflections and proposals. The experimentation was also conducted with the involvement of didactic experiences (seminars and applications) from which it was possible to deduce some useful reflections for further ideas, such as the perception of certain problems, the need to involve integrated communication systems and finally the development of specific applications. In this context, it is important to underline the role that social media play today in the dissemination of visual communications which, as a whole, amplify the perception of a brand's identity and allow for in-depth information on issues subject to sudden changes, just like the one mentioned as a premise.
The hydrodynamic assessment of double-ended ferries is always particularly challenging, not only due to their peculiar hull shape, but also because of the environment where they have to operate and its related constraints. The present paper discusses a practical case study of such hydrodynamic assessment for a double-ended ferry planned to operate in the Venice lagoon. The main objective of this study was to compare two propulsive configurations, with 2 or with 4 thrusters, both in terms of powering and manoeuvrability performances. Additional design requirements were good ship handling also in case of one propulsor failure and a limited drift angle. These requirements derive from the fact that the ship has to safely operate in the busy but narrow Venetian canals, sometimes even in presence of poor visibility due to fog.
The first step of the assessment was a hull optimisation by means of RANS calculations and taking into account the required adjustments in the hull between the two configurations. Successively, resistance and propulsion model tests highlighted the differences in powering performance between the two configurations. The tests also showed the optimal power distribution between fore and aft propulsion for both configurations.
The manoeuvring assessment also consisted in both experimental and numerical parts. First model tests were carried out for evaluating the low speed manoeuvrability of both configurations, including the case of one propulsor failure. Then the experimental results were used to tune a numerical model, which was used to perform a broader range of manoeuvres such as at high speeds or small helm angles.
In the end the results of this overall hydrodynamic assessment gave important indications on the performance of the ship and helped the definition of the optimal ship design.
As it is well known, during ship manoeuvres the propellers experience strong inflow variations. These can be ascribed to two main aspects. The first relates to the ship average speed reduction during the maneuverer itself, particularly evident for high rudder angles (as for turning circles cases). The second reason is the generated ship wakes, which become strongly asymmetrical due to the assumed ship navigation conditions. These modifications of the inflow to the propellers directly generate a variation of the propellers load and, consequently, variations of the requested engine power.
For specific engine layouts typical of twin-screw ships where, for instance, the two shaft lines are mechanical interconnected, the revolution rate of both the propellers are kept equals, generating strong mechanical stresses to one of the shaft lines.
This aspect needs to be accounted for during the preliminary design stages with the aim to improve the overall ship design by selecting the best engine layout or by adopting some control logic of the propulsion system.
The present paper explores the possibility (and the attainable level of accuracy) of predicting the shaft unbalance during strong manoeuvres by employing proper CFD tools in the case of some benchmark ships available in the literature. In particular, the attention is focused not only on the overall performances but also on the hydrodynamic features that causes the propeller load variations and the possible design strategies to reduce or monitor these effects.
The possibility of simulating the interaction of hull, propeller, and engine is gathering the interest of several researches in view of a more realistic design and control of the whole propulsion chain. The engine performance in rough seas is affected by the dynamics of the hull and consequently by the complex flow regime at the propeller, which induces fluctuating engine torques and revolutions.
In a previous research, the case study was limited to straight run simulations in irregular waves for a Ro-pax ferry, equipped with mechanical diesel propulsion. The numerical simulation model will be further developed for including the main engine behavior in waves, during maneuvering tasks. However, due to the limited data for the Ro-pax ferry considered so far, a comprehensive validation of maneuvering model currently seems not possible for this hull. Therefore, a well-known benchmark ship is introduced, i.e. the KVLCC2, for which several experimental test data are available in the technical literature. The focus on the numerical modeling for the KVLCC2 stays in the implementation of a comprehensive maneuvering model (i.e. including rudder propeller interactions), capable of simulating ship maneuvering in waves with a fair level of accuracy. Different approaches will be applied and compared. The comparisons between simulation and experimental data will disclose the range of applicability and the validity of the numerical models under investigation. Finally, the more appropriate approach for future applications concerning the overall assessment of the engine behavior in waves, will be selected.
When a vessel sails in a seaway, wind and current can influence the ship’s speed, the comfort on board and the fuel consumption. Maritime trades are strictly dependent on the environmental conditions that the ships encounter during their sailing, safe navigation and energy efficiency are the key factors to improve the competitiveness and sustainability of ship operations. Optimization algorithms provide a significant support to the decision-making process and allow selecting the best route in sight of one or more objectives. The weather routing problem has been addressed by many authors and different approaches have been proposed. The new route optimization procedure will be developed on the shortest path algorithm in order to maximize the ship seakeeping performances and to minimize the added resistance caused by sea conditions. The optimization will be performed in accordance with two objective functions, the best routing solution is thus selected by the Dijkstra algorithm modified to take into account dynamically changing of ship’s position and weather conditions. The maximization of a Seakeeping Performance Index, containing all the operability limiting criteria for induced vertical motions in rough sea, and of an Added Resistance Index, are the objectives to be achieved. The first for safe and comfortable navigation, the second for fuel saving, reducing the added resistance the engine power required to overcome the resistance and, as a result, the fuel consumptions decrease. The data of wind and sweel waves are derived, for each route segment, from global-WAM (GWAM) model. Results and discussion of the proposed method will be presented for a containership ship in a test case voyage through the Pacific Ocean, for ocean-going ships the voyage and sailing time are long and the weather conditions in the sea area around the route vary widely. The code can be integrated in an On-Board Decision Support System.
Mitigating flooding risk through passive and active measures is a key step in further increasing the safety of shipping, reducing loss of life and damage to the environment. Accurate modelling of flooding is of paramount importance, considering that this hazard remains the most significant contribution to the overall risk (up to 90% of the risk in passenger ships). Real time estimation of breach size after collision or grounding followed by a reliable flooding risk estimation (residual stability, time-to-sink or capsize vs. ship evacuation time) could be assessed through a screening process from the design stage, monitored during operation and made readily available to the crew during a flooding emergency through a decision support system. This, in turn, would provide valuable feedback to designers in their strife to constantly improve the effect of active and passive risk mitigation measures. The EU Horizon2020 project FLARE (FLooding Accident REsponse) introduces a novel risk-based methodology beyond the state-of-the-art for “live” flooding risk assessment and control, by developing a generic (all incidents in one model) and holistic (active and passive measures) risk model with potential application to new-buildings and to existing ships (which is totally new!).
Along the lines of FLARE, this paper reviews a range of potential applications and Risk Control Options (RCOs), including susceptibility to flooding accidents (pre-accident phase) and risk estimation beyond existing statistics. The susceptibility model is linked to a flooding accident model to assess - based on statistics and first-principles tools - the frequencies of flooding events whilst accounting for pertinent environmental conditions and design parameters, including such novel concepts as the crashworthiness of the ship. FLARE partners are key stakeholders in maritime safety, involved in the development of the probabilistic regulation for damage stability from the outset, with specific focus on passenger ships. After an evaluation of the cost-effectiveness of RCOs, the findings will be submitted to the IMO, suggesting possible recommendations and/or amendments to the regulatory framework.
The harvesting of wind energy and its transformation into a thrust force for ship propulsion is gaining in popularity due to the expected benefit in emission reduction. To exploit the benefit a proper integration between the conventional diesel engine-screw propeller propulsion plant and the wind-assisted plant is mandatory. A mathematical model describing the behaviour of the rotor in terms of propulsive thrust and power is proposed. The rotor model has been integrated into an existing diesel propulsion model in order to evaluate the ship's net fuel consumption. The methodology allows for the evaluation of the engine-propeller working points and finally the total ship propulsive power considering the influence of the rotor, for a given wind condition.
A 3000 tons Ro-Ro/Pax ferry has been selected as a case study. Results are presented about the parametric analysis of rotor dimensions and wind conditions. For a fixed wind condition the effect of the rotor at different ship speeds is presented.
Marine diesel engines are systems integrated into a complex ship’s propulsion plant and comprehensive diagnostic analysis of possible degradations and failures is very challenging. Nowadays, current software and hardware allow exploring innovative ways, although every methodology cannot be separated from an adequate onboard monitoring system. In this work, the effects of several typical degradations of a ship’s engine, affecting some parameters that can be monitored on board, have been supposed and analyzed. The main aim is to provide a tool able to trace the engine performance decay. The procedure is based on the simulation of the engine model performed with input data measured onboard and on comparison of the outcomes with the real data. The case study is a 12.000 kW (750 rpm) 4-stroke marine diesel engine, simulated in a Matlab/Simulink environment and validated through the manufacturer’s data sheet. At this stage of the research, to make up for the lack of experimental data recorded onboard, a more detailed engine simulator is used to generate onboard like data, with some alterations of the operating conditions as, intercooler efficiency and loss of pressure, turbocharger fouling, and many others.
The numerical diagnostic tool acts on the minimization of the mean square errors (optimization problem) between the measured and the numerically simulated engine variables (such as pressures, temperatures, etc…) by properly varying the model parameters. The state of the engine is evaluated by analyzing the offset between the parameters of the undegraded model and those obtained through the identification procedure for the degraded case.
Numerical simulations currently represent a valid aid to assess the performance of marine engines. Anyway, most of past applications generally focused on large supercharged 4-stroke diesel engines, while few results are available in the literature for fast outboard engines, generally installed onboard of recreational crafts. Therefore, a case study on a fast outboard diesel engine (4T, 6300 rpm, 350 hp) is currently provided and discussed. The simulations are performed in the Ricardo Wave environment. Besides, NOX and CO emissions are estimated, in addition to the typical engine performances. The data, required for the model calibration, were obtained from the engine manufacturer datasheets, as well as from a set of available sea trials. Nevertheless, not all parameters were available, so as some of them have been selected based on past experience or in accordance with similarly sized diesel engines, after performing a preliminary sensitivity analysis. As concerns the assessment of NOX and CO emissions, different simulation methods are embodied to assess the chemical equilibrium in the combustion chamber and investigate the relevant incidence in terms of time effort amount, and estimated results. Current simulations reveal to be also useful to model dual fuel (gasoline/natural gas) engines and evaluate the impact of this type of alternative plant on consumptions and air emissions.
In recent times the ship building and yacht industries have seen a surge in the requests for the application to the power generation, conversion and energy storage of technologies which were previously reserved to land-based uses or to niche sectors such as space, military, and scientific research. Such requests are often driven by seeking cleaner exhaust emissions, more efficient fuel consumption and higher passenger and crew comfort. Among these novel technologies we can mention fuel cells and (large) batteries based on Li-ion chemistries. These solutions are not only unconventional per se, they also carry along the necessity for advanced electrical system integration (even more so if combined in a hybrid architecture) or, for fuel cells, the need for the storage of dedicated fuels, e.g. liquid or compressed hydrogen or methanol, and fuel treatment, e.g. evaporators and chemical reformers. The lack of prescriptive regulations covering such innovative solutions, both in terms of equipment and fuel, adds in challenge to their acceptance and certification from Regulatory Bodies and Flag Administrations. Furthermore, although high-level guidelines are provided, they often need to be tailored on a case-by-case basis and integrated with risk assessment exercises. The aim of this work is to give a comprehensive overview of the Classification tools available to date – be it prescriptive or risk-based – for the approval of novel designs and how do they relate to the existing statutory guidelines and to the established risk analysis instruments. The discussion will be corroborated by insights into some hands-on case studies in the yacht and cruise ship industry segments.
This paper supports decarbonisation in the marine industry by illustrating that a proper design methodology and state of the art technologies can significantly reduce greenhouse gas emissions.
In particular the paper aims to demonstrate the possibility of reducing the environmental footprint of Marine High-Speed passenger transportation with an innovative propulsion plant design. The challenging solutions to designing a high-speed hybrid catamaran ferry, that satisfy design criteria and requirements, are presented and applied to a realistic case study. The design process takes several aspects of the design spiral into consideration and investigates the potential electrification of the vessel to reduce its carbon footprint without compromising function and performance. Furthermore, the optimal selection of the propulsion system and components, along with the preliminary design of the vessel are outlined and justified. To conclude, the environmental benefits of the proposed propulsion plant design are presented and discussed: a comparison with a conventional propulsion system is carried out by using measurable parameters similar to those of the EEDI.
The maritime transport is guilty for about 2.5% of global greenhouse gases emission, since 940 million tonnes of CO2 are emitted around every year [1]. Moreover, even though now the 96% of ships can be recycled, current recycling practices cause negative environmental impacts. Indeed, researches carried out on ‘ships graveyard’ showed a concentration of petroleum hydrocarbons 16,793% higher than at the control [2]. Epoxy Fibres Reinforced Composites (FRCs) are sustainable candidates in this field. In fact, having the FRCs structures a light weight, fuel-efficient ships can be built. The global epoxy composites market size was valued at USD 25.32 billion in 2019 and is expected to expand at a compound annual growth rate (CAGR) of 6.2% from 2020 to 2027 [3]. In this sense, in the next few years, the market is expected to rapidly replace conventional materials with epoxy composites in several fields, including the marine one. However, concerns about their non-recyclability are rising more and more. In this study, by following a twofold “design for recycling” and “design from recycling” approach the chemical recycling process for thermoset polymer composites developed by Connora Technologies (California, USA) was considered as solution to overcome this issue. Moreover, the adoption of natural fibres, i.e. flax, and biobased epoxy resin was used as environmentally-friendly solution to even avoid the use of petroleum based raw materials. To follow the first approach, i.e. “design for recycling”, Flax FRCs with bioepoxy matrices were first produced via hand lay-up with vacuum bagging. Next, they were chemically treated to obtain a recycled thermoplastic (rTP). Then moving on the “design from recycling” approach, a reuse strategy was developed by exploiting the Electrospinning technique and producing electrospun fibers suitable for the interlaminar toughening of composite laminates.
References
[1] https://ec.europa.eu/clima/policies/transport/shipping_en
[2] Science for Environment Policy (2016). “Ship recycling: reducing human and environmental impacts”. Thematic Issue 55. Issue produced for the European Commission DG Environment by the Science Communication Unit, UWE, Bristol.
[3] “Epoxy Composites Market Size, Share & Trends Analysis Report By Fiber Type (Glass Fiber, Carbon Fiber), By End Use (Automotive & Transportation, Wind Energy), By Region, And Segment Forecasts, 2020 – 2027”, Market Analysis Report, 2020. Report ID: GVR-4-68039-095-9.
The aluminium alloys most commonly used in the marine sector are those of the 5xxx (Al-Mg) and 6xxx (Al-Mg-Si) series, as they can guarantee both a good mechanical behaviour and good resistance to corrosion which is one of the main properties required for materials used in the marine constructions: sea water in fact contains high amounts of chlorides that can cause, after short exposure times, the failure of entire metal structures.
Since in a boat there is the coexistence of different materials, it is inevitable that some of them must be welded together: welds between dissimilar materials often require the use of non-traditional techniques, such as the process of Friction Stir Welding (FSW) and explosion welding.
In this work, the resistance to corrosion of welds made using the FSW technique between dissimilar aluminium alloys, AA5083 and AA6082, has been studied: this particular process ensures the achievement of joints with excellent mechanical properties and almost free from defects.
The behaviour of the various alloys in free immersion has been studied through polarization curves carried out on an area of 0.79 cm^2 and monitoring the open circuit potential (OCP) of the different samples for 24 hours. The characterization of the galvanic couplings between the various materials was performed by measuring over time the short-circuit currents and the OCP of the individual alloys, and observing by Scanning Electron Microscope (SEM) the surfaces of the samples before and after the test.
Potentiodynamic polarization tests with microcells were then carried out on the three different weld joints, in order to obtain information on their corrosion behaviour. Then, after metallographic attack, the microstructure of the joints was studied, paying particular attention to the characteristics of the interfaces between the different aluminium alloys in the thermo-mechanically altered areas and in the mixing areas.
The shifting of the neutral axis in the cross section of ship structures is an important result of progressive collapse analyses. Especially for damaged ship structures where the load carrying capacity is reduced, to ensure a safe salvage operation, the residual hull girder strength has to be estimated rapidly.
The main purpose of the present study is to apply a Deep Neural Network (DNN) method to linear systems and estimate in a relatively short time span the shift of the neutral axis for intact and damaged ships by presenting their performances and highlighting the definition of DNN inputs.
First, the initial source data related to the intact condition and several symmetric damaged grounding scenarios of five different vessels (Double Hull Oil Tanker, Single Hull Tanker, 1350 TEU Container Vessel, 3500 TEU Container Vessel, Bulk Carrier) have been determined with a self-developed code based on the well-established Smith Method as an iterative incremental approach. The preliminary data has been validated against Bureau Veritas’s software MARS 3.0.1.
Second, a Deep Neural Network approach composed by multiple fully connected layers with a Rectified Linear Unit (ReLU) non-linear activation function has been applied to over 6000 samples and validated using leave-one-out validation, where one subject is entirely excluded from the training set in order to check the generalization capabilities of the neural network on a new unknown data set.
Finally, the shift of the neutral axis has been predicted for a set of completely new damage scenarios of a ship cross section, demonstrating that the deep neural analysis approach can estimate the neutral axis performance for a correlated damage index. It is expected that this study would be a novel approach, when dealing with hull girder analysis of damaged ship cross sections.
THALASSA is a large research project, developed in the field of the naval structures. It aimed at studying innovative solutions of significant impact in increasing environmental sustainability through a weight reduction, a careful production planning and a circular approach to the entire life cycle of the parts, from design to the disposal/recycle/reuse. The project is led by NAVTEC Technological District and it is composed of a large team counting more than 300 researchers of several centres among which the CNR institutes, the Universities of Messina, Palermo, Catania, Roma “La Sapienza”, and Udine. Innovative solutions for industrial processes of greatest interest for some major national shipbuilding operators such as Azimut Benetti and Fincantieri or for shipowner such as Caronte&Tourits have been investigated, and players such as ATRIA paint factory have been assisted in the formulation of innovative coatings.
The presence of NAVTEC District has allowed to concentrate the field of action on themes of strong industrial interest and at the same time to widen the research action on a number of different topics with a view on the entire product life cycle. The district allowed to network skills, laboratories and resources that individually would not have led to carry out activities on such a high number of variables, in terms of materials and joint types. Several issues have been addressed, by identifying solutions thanks to skills of the industrial players, such as: joining technologies (i.e. etching / texturing laser, clinching, self piercing riveting, co-curing, bonding, friction stir welding); eco and bio-sustainable composite reinforced by natural (i.e. vegetable or mineral) and hybrid fibres; degree of recoverability of traditional or bio-resins; corrosion of conventional metal structures and processes for increasing the useful life; and innovative coatings that are combined with the functional protection needs of the structures.
Integration of lightweight and sustainable solutions in marine structures design is essential to achieve weight reduction goals and improve structural response. A key step to assess the reliability of innovative structural solutions is represented by large-scale experimental investigation.
The current paper deals with the analysis of a lightweight ship balcony overhang, which includes an aluminium honeycomb sandwich structure and bimetallic welded joints. The design of the ship balcony overhang was previously performed, as an illustrative example, with the aim of suggesting the replacement of common marine structures with more green and lightweight alternatives.
In order to validate the design procedure and to assess the feasibility of the suggested solution, an experimental investigation on a large-scale structure was performed. The ship balcony overhang was tested under bending with a configuration representative of severe loading conditions for ships balconies. The experimental analysis allowed the evaluation of the structure’s strength, stiffness and failure modes, which are useful data to improve the design methodology of such structures and to calibrate numerical models. Comparison with similar structures reported in literature were performed in order to assess the benefits and drawbacks of the suggested lightweight structure.
Nowadays, that ships could reach incredible performances and new technologies permits to design beautiful lines, the real challenge is to build quiet and vibration free ships.
But to pursue the noise and vibration comfort during both design and construction is not an easy path. The research of new most performing solutions, but also material, is a challenge. During the design phase shipyards must pay attention to all details regarding the choice of machineries, materials and design solutions in order to improve comfort without penalize usability and technical characteristics. In order to balance all those characteristics noise and vibration predictions (based on experience and software analysis) are performed during design phase.
FEM and SEA analysis, supported by technical experience, permit to predict in advance noise and vibration problems, to reduce weights and costs and to build more comfortable ships for passengers and crew.
Thanks to these analyses, during final measurements onboard no surprises are awaited and no corrective measures are necessary.
What is pollution? The answer might seem obvious. Typically, pollution is considered as the diffusion of toxic or harmful materials on our earth. But pollution can also refer to the propagation of dangerous or harmful sounds in the environment, both in the water and the air.
Every day noise emitted by ships disturbs marine fauna, during navigation, and humans, during port operations. Nowadays, noise pollution reduction is an important theme that is regularly discussed in maritime committees and many countries are developing new regulations to restrict noise, both underwater and in port, and rewarding low emissions ships.
In this evolving field, Classification Societies, developing new regulations, could really make the difference informing, supporting and guiding shipyard and owners in reducing noise pollution.
Every time we talk about reducing emissions we think of expensive investments. Instead, you can protect the environment with an advantage also for your wallet! How? Making resources last longer! How? Maintaining them! Have you ever thought of filtering the oil (be it synthetic or mineral) on board, regardless of its function (fuel or lubricant)? If you do, the fluid will last longer with the following benefits
1) Reduction of supplies: oil lasts longer, you have to buy less
2) Reduction of CO2 emissions by reducing waste oil to be disposed of (1 liter of waste oil produces 2.6 kg of CO2)
3) CO2 reduction due to the reduction of transport for the supply of new fluid
4) CO2 reduction due to the reduction of transport for components that fail due to the wear of consumable components of generators, motors, winches, winches, etc.
5) Lower consumption for energy needs (today if you do something you do it using centrifuges that have a high consumption for heat production)
6) Fewer failures and consequent repairs and replacement of components.
Nowadays, the topic of hybrid marine energy systems is becoming increasingly relevant – this trend is mostly driven by the constant demand for safer and more efficient powertrains while being further accelerated by initiatives like zero-emission shipping, the initial IMO GHG 2050 strategy or such instruments as EEDI, EEXI or CII.
In this respect, the present study focuses on the domain of ocean-going vessels propelled by large 2-stroke marine engines and, in particular, on the challenges of a properly integrated propulsion system. Virtualising the integrated system, using transient-capable components models provides plausible quantitative figures about its performance and enables informed decisions at early stage. To this end, the paper highlights two findings – first, the importance of component “rightsizing” and, second, the necessity for intelligent operation of those components. Embarking on an analysis of a wide range of customer studies for various vessel types (PCTC, Container, LNGC, etc.) it is demonstrated how each use case may lead to another optimal solution. For instance, utilizing the power-take-off (PTO) functionality for genset replacement might be generally feasible but its efficacy, due to the interaction of main engine and shaft generator, depends highly on the intended vessel operation. Another example is the arguably inefficient peak shaving functionality which, if only applied in a suitable situation (e.g. for genset load balancing), still may provide benefit to the overall system efficiency.
The paper remarks the importance of a virtual tool to support the hybridisation of marine vessels. Such tool allows for the identification of potential risks and criticalities in a very early stage as well as for reduction of calibration effort and risk of failure during commissioning.
The aim of the study is to evaluate from a technical and economic point of view, the feasibility of creating an innovative High Voltage Shore Connection (HVSC), at a major Mediterranean port. The purpose is to enable two cruise ships to simultaneously connect to the Port’s electric grid, thus permitting the ships to switch off the main engines and so reduce environmental footprint when docked. Additionally, the study considers the integration into the Port electric grid of Distributed Energy Sources (DES) from renewables and Energy Storage Systems (ESS) to limit the supply of energy from the public grid to a single connection point.
In summary, the main objectives of this study are to assess the feasibility of:
• Developing a HVSC facility in order to connect two cruise ships at the same time to the Port electric grid,
• Electrifying a selected number of strategic locations within the Port to serve two cruise ships, whether at berth in the cruise terminal or in a dry-dock,
• Integrating distributed renewable energy generation systems in order to increase the availability of HVSC power and reduce the Port’s environmental footprint, possibly also decreasing the unit cost of energy for the end user,
• Integrating a suitable Energy Storage system (ESS) to optimize usage of the energy generated by DES,
• Identifying any reinforcement/expansion work required for the existing Port grid and associated civil engineering/structural modifications; as well as any shipside interventions required to allow the use of a HVSC,
• Lowering pollutant emissions (SO2, NOx, CO2, and PM) at port,
• Financial investment and economic impact.
A number of seventeen models of Ferry in scale 1: 28.750 of 10250 ton displacement have been built at the Italian Model Basin, to be tested in the Emilio Castagneto towing tank N.2 at INM in Rome. The results of the tests have been collected in this report, delivered and presented in easy and useful form. The hull C.2054 has been used to build the whole Serie, the variations in the forms have been obtained maintaining the same displacement, operating the deformation of the hull in the x, y, z directions using the following parameters:
p = L derived hull / L generating hull q = B derived hull / B generating hull r = T derived hull / T generating hull
The derived hulls have all constant volume, while the product p ˑ q ˑ r = 1, and constant will be also CB = 0.515, CM = 0.943, CP = 0.546, CW = 0.715, CVP =0.720, LCB = -1.71% , XCF = - 5.33%. The displacement = 10 250.0 ton is corresponding to 10 000 m3.
One definition of simulation is: an approximate imitation of the operation of a process or a system.
But the simulation is a natural brain process, in fact human beings continuously create simulations in their mind using the imagination to understand and predict their actions. From the simple prediction of a simple event to the imagination of a performance before a sport or an artistic event, our mind uses its simulation ability because it is designed and optimized to simulate.
For this reason, it is very easy for us to understand the concept of simulation and in fact Simulation, Virtual Reality and Mixed Reality often become the most effective and immediate ways to understand our reality.
There are many kinds of simulation but in Cetena, when we talk about simulation solutions, we refer to maritime real-time simulation that can be applied in different applications and fields.
Time-to-flood is a key parameter during a flooding emergency. In particular, when dealing with complex geometries it is important to know the time required to fill the first flooded room, i.e. the damaged one. Here, a fast solution for the assessment of the time-to-flood of one or two parallelepiped rooms is proposed. The progressive flooding of the rooms is first simulated employing a linearised simulation technique defining a database of damage cases covering a wide spectrum of geometries. Then, explicit equations based on the main non-dimensional parameters governing the phenomenon are defined. The work highlights the relation between the geometry of a room, the damage opening, the connection opening and the time to fill the first damaged room. The application of the equations is very fast, enabling an instantaneous estimation of the time-to-flood. Then, they are particularly suitable for a direct onboard application or during the generation of large datasets of flooding simulations.
The proper definition of the main geometric coefficients and the hull forms of a passenger catamaran must be carried out since the early stage design, due to its strong impact on the resistance, propulsion and the generated wave pattern. This is a primary concern especially in fragile environments, such as the Venice Lagoon, where waves increase erosion phenomena. In this work, a two-phase methodology for the definition of the hull forms of a passenger catamaran, based on both a parametric and CFD analysis, is presented. In the first phase, systematic series data are used to parametrically evaluate possible combinations of main hull dimensions (breadth of the demi-hull, deadrise angle), selecting the best one to fit a specific operative scenario (minimisation of required energy). Then, after the validation of mesh parameters with a benchmark hull, the best hull forms are assessed through CFD simulations. In order to study the interference between the two hulls and select the proper configuration two different distances of the demi-hulls are investigated. The methodology has been applied to the preliminary design of a 10.2 m passenger catamaran for the Venice Lagoon. Routes from the city centre to Marco Polo Airport or Torcello Island have been considered.
“..But this coronavirus has forced us into a new framework, within which we move without any ease: everything has new ways, everything appears as never seen, it's like finding yourself in an uncharted territory..” (G. Arma, 2020)
With these words Gennaro Arma, Captain of the Diamond Princess cruise ship, describes the very first moments following the detection of what would become the first recorded outbreak of Covid-19 outside of China. It occurred during a roundtrip cruise which departed from Yokohama port, in Japan, on 20 January 2020. Among the 3,700 people on board, more than 700 tested positive for the virus, 14 of whom died during hospitalization. A situation which was faced without the support of emergency protocols that contemplated a modus operandi to follow.
The ship constituted a confined control volume which allowed to analyze the main routes of virus propagation that mainly occur through direct contact between individuals, indirect one via contaminated objects and surfaces (also referred to as fomites) and airborne transmission. This has greatly affected the overall design paradigm, especially concerning the safety levels to be assured on board. The paper is going to analyze these focal points, starting from a possible implementation of HVAC system. It comes after an extensive study of the air flow circulation, as well as the application of filtering and purifications solutions, considering ship age and ventilation type, assessing the possibility of isolating those sectors of the plant acting on some areas dedicated to the management of emergency situations. Synoptically, there will be an extensive analysis related to the different surface types present on board and possible design interventions (i.e., smart materials).
The Diamond Princess experience represents the prime mover aimed at the world of scientific research at the formulation of design guidelines applicable to the world of cruise ships and, consequently, in the civil architecture field. The outcome results have helped to build a transversal, holistic know-how, thanks to which it will be possible to control the occurrence of future pandemic episodes.
In the last years, the idea of implementing “greener” and sustainable solutions merged with the basic principles of life cycle assessment concept has turned to be of paramount importance for the boatbuilding industry. In this framework, construction technologies based on wood such as strip-planking represent possible solutions, as they allow the use of a natural-grown material for attaining refined and solid structures. However, since these techniques imply wood bonding through conventional epoxy adhesives, the global eco-friendliness of the final product is lowered. As a consequence, the adoption of innovative bio-based adhesives is a promising solution to investigate. It is known that, generally, bonded joints in wooden hulls are weak spots of the structure, so the performances of the used adhesives should be duly assessed in order to guarantee an effective bonding. In the present research activity, the assessment of the performances of bonded joints manufactured with bio-adhesives is carried out through a FEM-based methodology, starting from the data present in the technical datasheets of the materials used. In such a way, the most promising products can be preliminarily identified in order to deeply investigate their mechanical characteristics through experimental tests, so limiting expensive and time-consuming activities. The proposed methodology was validated through the comparison between the results coming from the FE analysis and the ones stemming from experimental tests. Moreover, the proposed methodology could be profitably used to analyse more complex geometries, such as real and large structures of wooden hulls.
Since early 1960s the marine industry has experienced an increasing use of composites from small boats to submarines. Traditional marine composites are woven glass/carbon reinforced thermosetting polyester/vinyl ester resins produced by hand lay-up, but the development of low-styrene emission resins, the vacuum resin infusion process and stitched fabrics have all contributed to improve composite quality. However, over recent years there have been some significant changes in both the materials and their applications. For example, increasing concern about environmental impact has favoured a move towards bio-sourced and recyclable matrix polymers and fibres. In the framework of the THALASSA project, collaboration among universities, research centres and companies is striving to develop greener alternatives to traditional composites and surface treatments for joining dissimilar materials. The present work is focused on the development and mechanical characterization of composite laminates reinforced with natural basalt and flax fibres while exploiting innovative recyclable and bio-based epoxy formulations suitable to resin infusion based on bio-based epoxy monomers and a cleavable ammine. In an attempt to providing access to recyclable materials with existing manufacturing technology, comparisons are also provided with EliumTM acrylic resins that can be infused like vinyl ester but then react to form thermoplastics, which can subsequently be recycled. In addition, an alternative anodizing process based on environmentally friendly chromium-free electrolytes has been developed to enhance the bonding strength of adhesive co-cured joints in double-strap configurations for nautical applications. Joint strengths have been evaluated under quasi-static loading, under transverse normal impact load at different temperatures and after an artificial salt fog ageing to assess their durability in marine environments. Results showed that the application of recyclable materials in the marine sector is of particular interest and due to their intrinsic characteristics, can lead to the solution of many problems and to improved performance.
In recent years, the maritime sector has become increasingly interested in environmental sustainability issues, leading to the development of innovative technologies and materials. Seldom these solutions were analyzed with a life cycle approach and, when this has been done, the studies have been carried out without a reproducible methodology.
The lack of a standardized methodology based on Life Cycle Assessment prevents a fair comparison between studies carried out on different vessels or technological solutions. As a result, determining whether the new solution or the new material employed is more sustainable than the prior one is difficult.
The aim of the project was to develop a Product Category Rules (PCR), i.e. the standard that defines the rules for the publication of environmental labels based on Life Cycle Assessment (LCA) studies, based on ISO 14044 and ISO 14025, that could be used on a wide variety of vessel categories. This work presents the approach adopted for the development of the PCR, in order to produce comparable outcomes among different investigations.
This article also includes an LCA analysis of a boat that represents one of the standard’s field of application’s extremes, in order to confirm and verify our approach’s applicability.
Indeed, we conducted a through investigation of a racing sailing boat built in composite material, whose components are all made by recyclable and recycled materials, i.e., a thermoplastic matrix filled with linen natural fibers.
Ship structures are subjected to various types of loads during their lifetime. Different numerical methods exist to determine the ultimate bending moment of ships by taking the strength reduction of structural members into account. The Finite Element Method (FEM) as well as Smith’s method are feasible tools to perform progressive collapse analyses of large structural systems under consideration of material and geometrical nonlinearities. The influence of initial imperfections due to welding has to be considered for ultimate strength prediction.
In this paper, nonlinear finite element analyses are performed to determine the ultimate strength of a container vessel under vertical, horizontal and biaxial bending. The implicit ANSYS solver is applied successfully for the different load cases. A parametric finite element model is developed and the influence of different approaches for nonlinear material model, mesh size and model length on the ultimate hull girder strength is demonstrated for hogging and sagging conditions. An appropriate parameter set with respect to numerical efforts and accuracy is used to analyze the horizontal bending and combined biaxial load cases. Displacement controlled nonlinear finite element analyses are performed to ensure constant rotation ratios of the cross section in biaxial bending. Convergence is reached by using the full Newton-Raphson scheme as an incremental iterative solution approach. The results are validated against the well-established Smith method.
The cross section of the container vessel is composed of stiffened plate panels. The stiffeners are connected by fillet welding to the plating and butt welding is used to connect the plate panels. Due to the welding process initial deflections and residual stresses are produced. For the proposed finite element model initial deflections of plating and stiffeners have been considered. Furthermore, the influence of welding residual stresses on the ultimate hull girder strength is analyzed for the different load cases.
The need of lowering the weight of ships makes it crucial to have superstructures made of aluminum alloy and the ship hull made of steel. Within this context, the connection between the two different metals becomes crucial as different metals are hardly weldable using traditional techniques. Thus Structural Transition Joints are extremely important. One of the most promising welding techniques is the Explosion Welding process, which reaches a good compromise between weldability and mechanical properties of Structural Transition Joints. In the present study, the mechanical behaviour of Structural Transition Joints made of ASTM A516 structural steel, clad by explosion welding with AA5086 aluminum alloy and provided with an intermediate layer of pure aluminum was investigated. Preliminary fracture mechanics tests on CT Specimens made of Al alloy and shipbuilding grade steel were performed. Afterwards, fracture mechanics properties of the Structural Transition Joint considering a notch located at the interface between the pure aluminum and steel were evaluated experimentally following the current standards. In addition, the Digital Image Correlation technique allowed the analysis of the displacement and strain patterns of the different metals and to evaluate the crack length of the bimetallic specimen.
Ecospray is actively working on projects for carbon capture, using three different technologies for removing CO2 from exhaust gas:
•Fuel cells, for removing and concentrating CO2
•Amines scrubbing, for chemical removal of CO2
•Calcium hydroxide scrubbing, for CO2 chemical removal and permanent carbon mineralization
Ecospray is developing Molten Carbonate Fuel Cell technology (high temperature cells operating with molten carbonate as electrolyte) as a unique solution that reduces costs and environmental impact coupling carbon capture with energy production.
In the current stage of development, with also a specific laboratory in partnership with Genoa University, our Carbon Friendly Fuel Cells are designed to be fueled with ammonia or methane, producing energy very efficiently and acting as CO2 concentrators too.
The low concentrated CO2 in the exhaust gas of engines can be fed to the cathode and up to 90% of the CO2 is then captured and therefore transferred to the anode. The resulting concentrated CO2 can be easily separated and liquefied for further usage.
Ecospray aims to achieve with this project, started in 2019 with several European partners, the first large-scale maritime implementation program of CO2 capturing technologies.
In the Amines scrubbing technology, part of the exhaust gas is extracted downstream the existing DeSOx tower and sent to an additional reactor where an amine solution flow is recirculated in a closed loop process, absorbing the CO2 from the gas stream. When amine flow is regenerated, CO2 is captured and liquefied (for onboard storing)
In the last project CaO/Ca(OH)2 is bunkered and stored onboard as a solid bulk powder. It is mixed with water and injected directly into an auxiliary dedicated scrubber, absorbing CO2. As a result, the environmentally safe product containing captured Carbon, is discharged overboard.
Deadlines for onboard or prototypes in Ecospray laboratories testing are all fixed for middle 2022.
The coastal passenger transport in touristic areas like Costa Smeralda (Sardinia), Cinque terre (Liguria) , Costiera Amalfitana (Campania) , Venetian Lagoon (Veneto) and others, is constantly growing. At the same, time the sensitivity of authorities to the issue of environmental impact in those areas is leading the transportation companies to investigate technical solutions that can guarantee high volumes of passenger being as much as possible eco-friendly.
Hybrid or full electric passenger vessels are becoming more and more popular, starting from this assumption the authors examined the possibility to combine state of art technologies, with an innovative approach to match the propulsion system with hull resistance data, in order to propose a passenger ferry capable to operate in protected areas with an extremely low impact on the environment and taking advantage also from a basic energy distribution ashore. The usage of new generation batteries, with the highest safety standards, will be also investigated.
The paper starts from the determination of the operative profile for the ferry, evaluating the best solution in terms of efficiency and power management, considering the resistance data of various hulls, focusing on a traditional displacement hull, and then developing a study of the propulsion system through the usage of last generation generators with variable speed and batteries different from traditional Li-Po, in order to achieve a high efficiency level.
Emerging energy efficiency regulations and ongoing industrial studies are boosting the reduction of ship pollutant emissions. Researches are progressively stimulating innovation in energy efficiency management allowing the adoption of new technologies by shipowners.
In order to find new strategies to reach Greenhouse Gas (GHG) goals, the IMO imposed new technical requirements to reduce carbon intensity by means the Energy Efficiency Existing Ship (EEXI) Index. This new technical measure is compulsory for existing ships. These indexes estimates grams of CO2 per transport work (g of CO2 per tonne-mile).
For each vessel in operation an Attained EEXI must be calculated and benchmarked for compliance with a Required EEXI.
The parameters that have the greatest impact on the determination of the Attained EEXI values will be assessed and compared the Required EEXI. Therefore, case by case, different technical solutions able to reduce the EEXI Exceedance percentage (i.e. the difference between the Attained EEXI and the Required EEXI) are tailored for each vessel with reference to the operating profile/scenario. Furthermore, in this paper a case study referred to a merchant fleet engaged in global operations is presented.
In recent years the acknowledgement of the relations between the emissions of exhaust gas, in particular CO2, and their effects on climate and environment has grown to a wide level. Many countries and international organizations have begun to work to mitigate the problem and drive the society towards more sustainable sources of energy. Shipping is no exception and in 2018 the IMO – International Maritime Organization set the ambitious goal of reducing the CO2 emissions of the shipping industries of at least 50% within 2050, compared to the levels of 2008. This has introduced the need to research and develop new, sustainable energy sources and power systems for ships. The REShiP projects is aimed to identify a type of ship which would be suitable for an early adoption of a carbon free or carbon neutral fuel and a matching power generation system, tailored on specific routes. A small ferry powered by a hybrid combination of liquid hydrogen-fuelled fuel cells and Li-ion batteries has thus been identified. A mathematical model was developed to optimize the usage of fuel cell and batteries based on the ship operative profile. A multi objective optimization was implemented to minimize system performance degradation. To support the mathematical model a 7 kW PEMFC power generating unit was assembled and relevant data have been analysed. Following a regulatory framework research and in lack of comprehensive prescriptive rules, the design of the ferry and the prototype was done in accordance with the alternative design approach based on the risk assessment methodology, reaching a level of confidence appropriate to award an approval in principle.
Never more so than during the Covid-19 pandemic, technology has shown its potential to avoid or minimise business disruption to the maritime industry. Digitalization is playing a key role in being resilient and efficient, while remotization is the new normality in everyday work. Being able to transfer such technologies to the shipping sector and use them to take data driven decisions, enhance regulatory compliance and monitor the asset life cycle can give to owners and shipping companies real advantages in facing the new challenges the business faces.
In the actual and near future, one of the major challenges that the marine sector must face is represented by the global decarbonization targets, which will impose strong changes to the whole shipping sector. Due to these ambitious targets, in the next future every shipping company will be forced to work on three main pillars: new fuels, new technologies and optimized operational measures.
Fleet performance management and digitalization can play a key role in the optimization of the operational measures: monitoring efficiency, ensuring compliance with the upcoming regulations and optimizing reporting operations thus reducing the burden on-board.
With the upcoming regulations, it will become even more important to always know how a vessel is performing, being capable of simulating the ship’s behavior in different operational conditions and reduce the carbon footprint by deploying the whole fleet in the most efficient way. When the vessels emissions need to be reduced as much as possible, the focus should also be on how to collect the information on board, ensure that the information is reliable and have tools to manage such data to enhance decision making together with proving efficiency gains after new technologies application.
This paper explains the importance of data collection and how digital tools are starting to permeate the life of the shipping companies, helping both onboard and ashore personnel in enhancing operations: from electronic logbooks to live monitoring of scrubber systems, from collecting data on board to building the hydrodynamic digital twin of the vessel to be used in weather routing applications.
The actual, global pandemic situation has dramatically involved every aspect of our lives. This also greatly affected the cruise ship industry. At first, cruise companies tried to face the problem by adapting existing ships at the situation, with no time to rethink completely their project. The opinion of scientists, architects and experts in the field highlighted the need to devise a new way to design cruise ships, considering passenger management, marketing, medical aspects.
Particular attention must be paid to public areas, where individuals would be most vulnerable to airborne transmission. The sanitizing operations have now to follow even stricter operational protocols than in the past. A constant update monitoring of the passenger flows through the so-called smart technologies this would allow, when dealing with a suspected case, to trace a timeline of its activities on board and, therefore, to avoid the rise of an outbreak. The implementation of the overall efficiency of vertical connections (which helps the management of potentially contaminated waste) and on-board medical spaces such as the hospital and the pharmacy, nerve canters in cases of a health emergency.
From an anthropological point of view, it is essential to consider in more depth issues such as social distancing and the possibility of permanently decreasing the number of passengers in favour of safety and on-board liveability.
In the post COVID-19 era, the cruise ship can become a "health bubble", a microcosm where people can feel safe again and live an even more rewarding and safe experience.
Digital twins are computational models that replicate the structure, behaviour and overall characteristics of a physical asset in the digital world. In the maritime domain, conventional approaches have relied on mathematical modeling (e.g. linearised equations of motion) and heavy computations for estimating ship resistance and propulsion, seakeeping and maneuverability and overall hull form optimization, treating the vessel as a point body. For instance, the ability to predict a vessel's future track in confined or congested waters presents a significant challenge due to the fact that as time passes, these models often fall out of sync with their digital counterparts due to changes that happen to the ship (e.g. foulding affecting maneuverability). In addition to this, mostly due to computational resources required, in real world deployments models are simplified, thus reducing their overall prediction accuracy..
In our work, we implement AI-enabled coupled abstractions of the asset-twin system, which rely on machine learning methods for constant learning of the evolving over time behavior of a vessel from historical data. The technical enhancements and practical performance improvements are demonstrated in a number of maritime industry pilots, aiming at real-time vessel traffic monitoring, short-sea autonomous vessel routing, etc. with the overall aim of global fleet intelligence.
What makes a successful ship design? The most brilliant solution cannot be called a success if it is something nobody desires. Nonetheless, if a solution can in principle fulfill customer’s needs but it is not appropriately executed, it is a failure as well. Therefore to have a successful solution both elements are crucial: getting the right design and getting the design right. Respectively they answer the question “ what is the right thing to build and why?” and “how do we build it?”.
The traditional design method, represented by the “design spiral”, is a solution-oriented approach that works well when requirements have already been defined. It surely results in a feasible ship possibly fulfilling the customer’s requirements, but it is not ascertained a priori that it is the best one from all point of views. The exploration of the problem domain, necessary to select the right design, can be achieved with a problem-oriented approach such as Systems Engineering (SE) methodology. The aim of SE is to identify the best possible solution that satisfies customer needs in the most efficient and effective way.
In this paper a new approach that merges the traditional ship design procedure with the Systems Engineering (SE) processes will be discussed, with a special focus on the conceptual integration between the SE V-model and the design spiral. In these perspective, it will be necessary to discuss the definitions of Measures of Performance (MOPs) and Measures of Effectiveness (MOEs). MOEs are related to the achievement of the mission in the intended operational environment, while MOPs characterize physical attributes of system/ subsystems.
The objective is to open a discussion within the naval architects community to define an innovative methodology which will support the decisional process in finding the best possible solution, in the specific domain of naval ships.
Reducing the human environmental impact is one of the most critical issues nowadays: in this perspective the progressive decommissioning of fossil fuels is a significant priority to guarantee a sustainable future for the next generations. This paper proposes a zero-emission ferry for inland waterways and short-sea navigation, focusing on realistic solutions to provide the best trade-off between operational performance and environmental sustainability. In particular, the object of this study is the refitting of a double-ended ferry working in the Lago Maggiore, one of the largest Italian lakes. Systems suitable for the purpose have been selected and integrated on board with a view to maximum efficiency, implementing full-electric propulsion with electric motors, a Li-ion battery storage system and photo-voltaic panels. The benefits and drawbacks of the considered technologies have been evaluated to select the most promising design solution, focusing on both on-board and on-shore impact in terms of compatibility with the existing infrastructures and considering life-cycle sustainability.
According to the historical and social context and the evolution of technologies, medical care on board ships has been a requirement of variable priority throughout in the ship design. Strangely, this statement is much more evident in the field of naval ships, where there is a greater probability of injured or sick personnel on ships when operating in warfare scenarios or humanitarian operations.
NATO provides simple prescriptive indications, which indicate the health care and assistance capabilities that naval units must offer. The classification describes the operational capabilities of the ship’s health facility using the word "Role", depending on the response in terms of available treatments. The level is assigned with progressively increasing capabilities from Role 1 up to Role 4, which requires a complete operational response. On naval ships, the need to integrate numerous requirements minimises the design margins regarding the use of on-board volumes.
In spite of the particular mission profile of naval units, the medical treatment capability is often underestimated. Indeed, it is necessary to reserve an appropriate part of the overall space on board to rationally allocate adequate medical facilities. In this paper, the integration of innovative medical facilities with Role 2 Enhanced capability within the general arrangements of an LPD ship is presented. Furthermore, the hospital 90 m2 wide enables the dual-use of the military ship more effectively. Specifically, the accommodations on board are convertible to beds for patients, whilst complying with all safety and survivability criteria.
Almost all of us, even unknowingly, use technological products based on Euler's mathematical applications every day or, in school education, have encountered his formulas and proofs. However, much of his initial inspirations came from the unexpected and illuminating naval experiences, pushed first by the Prussian monarch Frederick II and then by the Tsarina Catherine II, to improve their fleets.
In the autumn of 1778, at the age of seventy-one, now almost blind, Euler, highly esteemed and known throughout Europe, is rearranging and writing down his notes of about sixty years of work in the study of his home in St. Petersburg; helped by his son Karl Johan and his young nephew Nikolai Fuss, both mathematicians, he intends to leave an orderly memory of it, a “not ungrateful gift”, to use his words.
The great mathematician talks to us about these studies in the first person, through the Author, in the book "1778, Long nights in St. Petersburg" which intends to condense, in a way that adheres to his works and autobiography, some of his intuitions and scientific contributions and in particular to the naval and nautical design of the Enlightenment century, still relevant, initiated and consolidated by the experiences lived on eighteenth-century vessels.
The quest for stability and speed in naval constructions has always attracted naval designers for both military and civil applications in the hyper-fast ferry segment; naturally the measures are not irrelevant and the evolution has led to tonnages and dimensions converging towards specific compromise values between speed, stability, strength, seakeeping, payload and comfort. These elements which, considered in their mutual relationship, are more than addenda but less than factors and such as to have made several past choices regarding joint effectiveness in military units fail, at least for certain countries. The article means to present a national innovative military Ultra Fast Offshore Vessel (UFO-V) project alternative to the classic deep V for offshore design hulls.
ITA Navy has started a new program for the acquisition of a Naval Vessel called SDO-SuRS (Special and Diving Operation – Submarine Rescue Ship).
In order to fulfill operational requirements, IT Navy has recently procured the so-called “SDO-SuRS Deployable Assets”. A temporary business grouping (RTI) between SAIPEM Spa (leader in robotics and offshore) and DRASS Srl (national excellence in the hyperbaric sector and rescue) is the enterprise selected for the scope. This grouping represents a national excellence and a technological reference point for IT Navy in the Submarine Escape and Rescue.
The new SDO-SuRS Deployable assets will have specific peculiarities such as: modularity, deployability, interoperability and complementarity.
Modular assets will be either installable on board the national mother ship SDO-SuRS or rapidly deployable in scalable configurations (from rapid intervention to deep rescue) on a vessel of opportunity, military or commercial, for far-from-home operations.
In order to establish a framework on damaged submarines rescue’s topic between Countries within ISMERLO (International Submarine Escape and Rescue Liaison Office) and NATO organizations, Italy offers the opportunity of providing any type of technical-administrative support in design, procurement, Life Management System or training of SAIPEM - DRASS systems, useful to a potential cooperation in the Submarine Escape and Rescue.
On the whole the above mentioned Submarine Rescue packages consist of a several assets as follow:
• Submarine Rescue Vehicle (SRV) tethered type composed by a Rescue Chamber and a WROV (Working Class Remote Operated Vehicle) which will be managed both aboard the SDO-SuRS ship (Mother Ship) and aboard the Vessel of Opportunity. The system has to be designed/realized to perform the search and rescue of DISSUB as well as the transfer of crew inside the Diving Decompression Chamber.
• Portable Launch and Recovery System (PLARS) to permit the Launch/Recovery of SRV/SRC and WROV;
• Diving Decompression Chambers (DDC) with TUP (Transit Under Pressure) to face a specific sanitary treatment which could involve the submarine’s crew;
• Ventilation System (VS) by means of which will be possible the change of dirty air inside of the distressed submarine as well as the air insufflation to main ballast tanks;
• Submarine Rescue Chamber (SRC);
• Working Class Remote Operated Vehicle (WROV) able to perform underwater work and completely redundant with the WROV associated to SRV.
The future of transportation means is quickly moving towards green solutions in order to reduce the emission of COx and SOx firstly and, secondly, to progressively abandon the fossil fuels. In this perspective, alternative propulsion such as fully electric engine, biofuels, hydrogen, LNG are now largely used in the automotive field and for mass transportation means. The naval field is now moving on the same trend by using hybrid and fully electric engine especially for pleasure vessels, where the relatively small engine power allows the installation of battery stacks onboard without adding unreasonable weight for only few navigation miles.
In this paper, the transformation of a traditional pleasure vessel towards a new hybrid version is proposed; after a more comprehensive view of the modifications that are necessary to install hybrid engine and battery onboard, highlighting all the critical aspects of these new design, a FE numerical analysis of the basement of electric variable speed generators is presented.
The design of the environment of a yacht or a ship must consider, among the many variables, the guest's experience and focus on its optimization; this means observing the modalities of interaction with the space and the objects that occupy it, acquiring the necessary information and, when possible, building a model capable of predicting, within a reasonable limit, the modalities of the interaction of different users.
An intelligent mock-up is a structure designed to monitor the user experience through a network of sensors integrated into the environment that reproduces the space to be designed. It also introduces the furniture elements and whatever else characterizes it in reality.
A dense network of optical, acoustic and piezoelectric sensors can return valuable information concerning both the visitor's interactions with the surrounding space and the perception of the environment itself by the occupants.
One of the central elements is represented by a network of high-resolution video cameras, which acquires, among other variables, the pupil diameter (mydriasis is, in fact, and some precise circumstances, a critical neuro-cognitive indicator) of the visitor by including it in a data set that, as a whole, contributes to the definition of a model of interaction between visitor and environment, built on a neuro-scientific basis.
Once validated, the model data can represent an essential aid for designing any interior space on ships and yachts without excluding different environments, smaller or located in extreme contexts.
Defense budget are shrinking and human resources are becoming more critical, while operational needs of Warships increase and change in the life cycle to face new threats.
To achieve the best balance between operational availability (Ao) and costs all along the life cycle, the sustainability requires a correct initial definition of the support followed by its continuous optimization, guaranteed by constant monitoring and analysis of the data coming back from the field, by a review of the reliability parameters, maintenance plan and spare parts list.
The ITN started a change management initiative from beginning of 2000’ through an optimization process by analyzing the return from the field data during the TGS FREMM contract, which has lasted for more than 10 years. This process consist of:
After the FREMM experience, Italian Navy is taking over all the activities performed so far by the private companies, for current and future shipbuilding programs (LSS, PPA and LHD).
The authors will go through the process set, tested for FREMM program, will show results after more than 10 years of experience, and will cover all the activities Italian Navy is taking care by itself for new programs, mentioning as well IT investments and available tools.
Submarines are vehicles where efficiency plays a key role in energy management: conventional submarines, with a diesel engine to recharge the batteries, rely on full electric propulsion.
The search for better performance in terms of efficiency and energy storage capacity, has led the World Navies with submarines, to develop alternatives to the classic lead-acid batteries.
The decision of the Italian Navy Submarine Flotilla to engineer the development of a LiB propulsion system aims to provide its submarines with greater autonomy and more installed energy.
Integrating this innovative technology into the new Near Future Submarine project, according to a design “space constraint” driven, involves the rethink of various critical aspects: starting from the choice of the manufacturing chemistry throughout the on board integration process, the risk assessment, the management of the entire life cycle, the spaces and weights distribution, the auxiliaries systems, involving also operational procedures for missions and the logistic supportability of the submarine in the home base and abroad, including details as maintenance at sea of LiB cells in reduced spaces.
In addition, this type of technology perfectly integrates with the NFS Air Independent Propulsion (AIP) system based on fuel cells: due to twenty years of operation use of the AIP Submarines, the ITN Submarine Flotilla has developed extremely specialized know how and mature skills on the production, storage, transportation, and consumption of hydrogen as modern energy carrier.
Future submarines powertrain will be like a grid and each energy source will be optimized to minimize the fuel consumption at the maximum efficiency.
The achieved results will be an incentive for further R&D also in the space sector, where lithium and hydrogen have coexisted for decades in spacecraft energy storage; once again, a strong technological correlation between submarine and spacecraft has been identified, confirming the similarities between the two.
Nowadays, underwater hulls have a wide range of applications both in the military and in scientific, commercial and security fields. Next to Submarines, Autonomous Underwater Vehicles (AUVs) are increasingly spreading thanks to their capabilities to carry out a significant variety of missions, including interacting with underwater infrastructures, coastal and underwater inspections, intelligence gathering, environmental and fish monitoring and, of course, research and fight against underwater threats.
One of the main performance characteristics of an underwater vehicle is its resistance curve. The estimation of this curve is a crucial factor in preliminary design phases in order to correctly choose and dimension the right propulsion plant and propeller and, in general, to reach operational requirements.
In the last decade, with the advent of higher computing power and robust algorithms, the application of Computational Fluid Dynamics (CFD) analysis is rapidly emerging as a fast, reliable and cost-effective tool in the assessment of the hydrodynamic performances.
The first part of the paper discusses the implementation of a simulation environment, a “virtual towing tank”, suitable for a generic underwater vehicle using a CFD software. A simulation is conducted and the numerical results are validated by comparing them with the available experimental data obtained from the literature.
In the second part of the paper, several modern technologies related to the underwater sector are analysed to identify their influence on the shape during the design phase of an underwater vehicle. Particular considerations are dedicated to the different positions and profiles of the sail allowed by the integration of the optronic periscopes. Further considerations are made on the shape of the bow necessary for the integration of sonars of different types and sizes. In conclusion, various tests are carried out in the virtual towing tank in order to detect the trend-line of optimisation for each case studies.
The sea mines are in the rank of the most infamous weapons of the war history and they are back again stronger than ever.
The 20th century witnessed the technical evolution of mines as well as the evolution of systems and platforms to counter them. Mine CounterMeasures (MCM) run after the evolution of the threat in an overwhelming technological competition.
Since the very end of the 20th century, the most advanced Navies together with Industries undertook studies aimed to “reduce the risk for crews” involved in MCM operations: with this focus some Navies aimed to keep the man out the minefield using Maritime Unmanned Systems (MUS).
Today, after twenty years of evolution of MUS, the dilemma is: “Is it possible to keep the man out of the minefield?”
Even though some stakeholders affirm that MCM can be conducted in a fully autonomous way, the truth is that the technologies are far enough to deliver a capability barely comparable to the conventional MCM Platforms in terms of effectiveness and reliability.
Taking into account these considerations, ITN and INTERMARINE are conducting a feasibility study on a new platform able “to provide the optimal pairing of manned and unmanned systems for MCM operations”. This challenge takes the name of “New Generation MCM Vessel (NGMV)”: the main feature of the project is to keep the shock resistance and underwater low signatures of legacy minehunters, while enhancing a massive use of MUS as extraordinary force multipliers and technological gap fillers thanks to a modular approach of platforms.
The paper conceives a flexible new generation Destroyer (DDX, Destroyer, Experimental) with primary focus on low environmental footprint, high efficiency and high reliability. The ship implements an innovative propulsion power generation and storage system based on a CODOGOL (COmbined Diesel Or Gas Or eLectric) architecture and a Battery Energy Storage System (BESS).
The proposed modular solution is suitable for retrofitting applications and is an innovation in the state of the art of hybrid propulsion systems for big, front-line naval ships. The shipboard BESS is used as a backup power source in order to ensure reliability requirements in Minimum Generator Operation (MGO) mode. The benefits of the proposed solution are discussed in detail, highlighting a reduction of the operating costs and fuel consumption, as well as low pollutant emissions and Life Cycle Cost. Moreover, dynamical simulation is used to assess the effectiveness of the proposed solution in critical conditions.
The Mission Package philosophy is tied to NATO concepts, indeed, the standardization of interface and procedures are essential for potential interoperability between Navies. Furthermore, the standardization and modularity offer opportunities of cooperation between Nations.
All NATO Navies are therefore facing the challenge of meeting current and future operational requirements while reducing procurement and life cycle cost of naval platform.
To this regard, the Italian Navy has adopted, over the last years, new design concepts in order to maximize operational flexibility for future needs by an extensive use of modularity features on its platforms.
The PPA experience combined with the mission package concept gives to the platform two levels of flexibility: in the short term, for the accomplishment of specific missions, known as Mission Modularity and the medium/long run to maintain “updated” the ship Mission capability.
This paper aims at underlining the Italian innovative approach used to develop the concepts of modularity and operational flexibility in the PPA experience emphasizing strengths and opportunities, as well as weaknesses and threats. While the PROs of modular equipment are more self-evident, there are also critical aspects to be considered. In fact, taking modularity to extreme might cause a too high reduction of platform performances in terms of: loss of accommodation space for the crew, in some cases loss of ship overall endurance, decrease of maximum speed and increase of vibration and noise.
Hence, only through an in-depth study on whole-warship design impact of Mission Bays and standardized modular areas, we would be able to underline the pros and cons of these concepts in the Italian Navy PPA experience.
The Italian Navy has always had, among its missions, the safeguard of the marine environment, and is strongly oriented to give its contribution to the targets fixed form the European Parliament with the European Green Deal.
In 2012, the Italian Navy launched the Green Fleet initiative, with the aim of reducing greenhouse gas emissions and improving national energy security.
To achieve these goals, the Italian Navy follows three main strategies:
- adoption of a renewable synthetic fuel;
- development and use of innovative eco-design technologies, which allow the reduction of the environmental impact of ships (LED lighting, SCR, foul release coatings);
- adoption of energy saving operating procedures (electric propulsion, energy dashboard).
The paper presents an overview of the Green Fleet initiative and a case study focused on increasing the overall efficiency of a ship by recycling the thermal energy normally released to the environment by diesel engines.
In fact, the overall efficiency of a diesel engine is about 40%, which means that 40% of the energy coming from the fuel is normally converted into usable power and the remainder is waste, which is delivered as heat to the environment.
The case study identifies an effective solution to use a significant portion of that energy, while reducing the ship's energy consumption, thereby increasing overall efficiency and reducing fuel consumption and greenhouse gas emissions during operations.
At the same time, the identified technical solution makes possible to reduce electrical load peaks, making the electrical load diagram more homogeneous, with the further result of optimizing the working conditions of the diesel engines.
Finally, the case study compares the proposed solution with traditional systems, calculating the time for Return of investment.
It is well known that during the life-cycle the growth of the shipweight is one of the main source of the performance loss. Stern flaps have been used in many recent designs of transom stern vessels, in particular by the US Navy, to increase top speed or to realize improvements in fuel economy over the operating range. Furthermore, stern flap implementation has also become a practical retrofit on existing platform because significant improvements can be achieved at minimal cost.
Ship Design Office of the Italian Navy General Staff performed a preliminary evaluation of the application of this device on own Destroyer hull (De La Penne Class), using the CFD U-RANSE approach and through experimental test campaign performer at Model Basin of CNR-INM (Council of National Research – Institute of Marine Engineering).
This preliminary study was conducted in model and full scale: several flap angles have been tested with a fixed NACA profile. The results have shown that the major improvements, in terms of power reduction, have been obtained for the operative speed range between Fr=0.335 and 0.419.
When subjected to a no contact underwater explosions (UNDEX), naval composite structures show highly nonlinear deformations. In this paper, fiberglass composite laminates are characterized dynamically. Experimentally, modal analyses are carried out to determine the modal parameters of the specimens, while dedicated shock tests are performed using the MIL S 901 D Medium Weight Shock Machine to measure their shock deformations. Numerically, a Finite Element model is set, running modal analyses and dynamic calculations to predict the structural response of different materials. In the end, results obtained by calculations are compared with experimental data, validating the model.
Using a Maritime Unmanned System (MUS) always involves a trade-off between the ability to autonomously accomplish tasks of increasing difficulty and the possibility for a human operator to take decisions concerning the ongoing mission. This aspect requires a communication architecture to share frequently updated information between the MUS and a Command and Control Station (C2S), capable of monitoring and supporting the system during its tasks.
Within this context, this paper describes a marine System of Systems (SoS), consisting of 3 collaborative MUSs, acting as an Anti-Submarine Warfare (ASW) passive barrier.
The preliminary experimental trials of the presented SoS took place in Sesimbra (Portugal), in September 2021, during the annual military exercise Robotic Experimentation and Prototyping augmented by Maritime Unmanned Systems (REPMUS), in which the Naval Support and Experimentation Centre (CSSN) of the Italian Navy was involved. In REPMUS-21, the capacity of the proposed system to detect artificial targets transiting in the operational area was demonstrated along with the capabilities of its multi-domain communication infrastructure, which allowed to monitor and control an underwater vehicle from a C2S exploiting a surface vehicle as a gateway.
In recent years, green shipping becomes one of the fundamental challenges for the marine industry: the limits imposed on ship emissions by IMO (International Maritime Organization) are increasingly stringent, especially in terms of SOx (sulfur oxides). The installation on board of scrubbers has proved to be a helpful solution to SOx abetment, in particular for the ships already in navigation: it allows to respect the limits imposed by the IMO even with the use of HFOs (Heavy Fuel Oils), so without the need to carry out a complete refitting of the propulsion system. However, such systems, usually installed in the funnels, have large dimensions. The integration between components is the best method to optimize the spaces, facilitating the installation of the scrubbers on board. The present work investigates a combined CFD-FEM (Computational Fluid Dynamics-Finite Element Method) methodology to evaluate the acoustic performances of a model-scale scrubber. Some papers in the literature consider the acoustic properties of SCRs (Selective Catalytic Reduction systems) for marine applications, while a thorough study on scrubbers' performances is missing. Independent CFD or FEM calculations may evaluate the acoustic properties of the scrubber. However, the combined methodology reduces the computational burden by about 90% compared to the CFD modelling. Moreover, it gives the advantage of considering the influence of flow on acoustic properties, which is impossible for a fully FEM approach.
In the field of green shipping the reduction of acoustic noise partially transmitted into water and the need of guarantee high comfort levels are important aspects in the view to agree with the UN 2030 Agenda in respect to life below water and good health and well-being. Both these aspects imply actions to increase absorption and dissipation of vibrational energy radiated towards the hull. To accomplish this effect, viscoelastic materials (VEM) characterized by high levels of damping are commonly used onboard ships (J. Fragasso et al., 2017, R. Kandasamy et al., 2016). In the last times, new strict requirements led to the development of Isocyanate free VEM, so the necessity of a provisional method to investigate in an efficient way new VEM is required.
Experimental tests are essential in order to obtain performance indicators (non-standard procedure) or material physical characteristics (Oberst’s beam test, ASTM E756 – 05). The implementation of the usual experimental setup could result rather complicated and it needs a high degree of accuracy, so in the last times finite element methods (FEM) has been increasingly used (Huang et al., 2020), even with the proposal of new element architectures. Knowing VEM physics parameters allows numerical simulation in both the provisional and the optimization phase to be accurate and reliable.
In this paper, an experimental-numerical method is proposed, with the aim of overtake the issues linked to the small-scale traditional cantilever beam test and paving the way to the selection of the most appropriate shape of the specimen. The innovation proposed through this method lies in the evaluation of the VEM complex modulus based on a reverse engineering approach, in which the loss factor estimation, contrarily from the traditional methods, is free from peak sharpness dependence. The proposed procedure is validated by comparison with the traditional method.
Until the Industrial Revolution, the concentration of greenhouse gases (GHG) (Carbon Dioxide, Methane, Nitrous Oxide, Ozone) in the atmosphere was quite constant; then human activities – such as burning of fossil fuels, industrial operations and deforestation – increased their concentrations, enhancing the natural greenhouse effect. According to the majority of the climate scientists, the warming observed since mid-20th century is mainly caused by human influence and there is a tight link between GHG pollution and global warming.
Recognizing the far-reaching and long-lasting consequences of the global warming for the planet, intense international debates at all levels take place to find possible responses to mitigate GHG emissions and reduce global warming effects.
The paper will present the high-level goals agreed at the UN Climate Changes Conferences (e.g. COP21 (Paris Agreement) and COP26) that boosted the discussion in important maritime fora and will critically review the new important and significant regulatory measures taken by the International Maritime Organization (IMO) and the European institutions and their impact on the maritime transport.
It will cover the IMO already adopted short-term measures (i.e. EEXI and CII) and the medium and long-term ones currently under discussion, such as carbon levy, life-cycle assessment and market-based measures.
A view on the very demanding climate targets in the EU for 2030 and 2050 (set by the European Climate Law adopted in June 2021) and the so-called “Fit for 55% Package” included in the legislative proposals to meet the 2030 objectives, will also complete the picture.
In recent years, a growing need has been observed in marine acoustics for the characterisation of low frequency materials below 100 Hz, particularly between 50 Hz and 100 Hz. The problem of sound insulation from airborne and low-frequency impact noise is becoming more and more relevant due to the considerable impact of sound sources at these frequencies, such as audio and video systems in theatres and discos, and TV systems inside cabins.
Current measurement procedures for identifying the sound insulation properties of bulkheads and floors are not sufficient to ensure repeatable and reproducible measurements, as their accuracy and precision values are too low to be accepted when applied at frequencies below 100 Hz. In fact, at low frequencies and in ordinary laboratory or room volumes (volumes between 40 m3 and 80 m3), the acoustic field is no longer diffuse due to the dominant presence of standing waves or resonant modes, which cause wide fluctuations in sound pressure level in space and frequency.
This study proposes and applies an experimental methodology based on the modal approach to study the low-frequency sound insulation phenomena below 100 Hz in the marine field.
Extensive experimental activity was conducted at the CETENA laboratories in Riva Trigoso, which made it possible to validate the measurement procedure and compare it with classical theories of sound transmission.
The development of this approach ensures significant support in the design phase for the optimisation of on-board sound insulation characteristics.
The publication of the Lloyd’s Register (LR) notation ‘Procedure for the Determination of Airborne Noise Emission from Marine Vessels’, in addition to port and civil regulations, may in the future result in shipowners requesting certification of the airborne noise levels emitted by their vessels. This certification may be required for access to particular areas of natural interest or to certain ports.
This study models the sound propagation induced by a cruise ship using three different software tools, starting with a database of measurements and calculations on the sound power generated by the main sources (fans, exhaust gases) in accordance with ISO 9614-1 and 9614-2. The results compared with real measurements in the far field showed the need to calibrate the models through a campaign of measurements of on-board sources in terms of sound power and pressure.
The experimental measurements of sound pressure and power in the vicinity of the main sources present on board the vessel, determined through an initial measurement campaign, were used as input for the numerical models. These models were developed using the three commercial software packages, estimating in advance the noise levels measured at different distances from the vessel (in particular in the positions indicated in the Class Notation). In a subsequent phase of the study, the estimated data were compared with those calculated through a second experimental measurement campaign performed under the operating conditions indicated by the Notation and at progressive distances from the vessel.
The simulations make it possible to estimate the contribution of the individual sources for any desired point and then intervene ad hoc to improve comfort levels in specific positions on board. The improvement in comfort levels can be obtained by optimising interventions on the sources to a minimum.
The development of this approach has resulted in a predictive tool with a degree of accuracy in the range required by ISO 9613 and therefore capable of assessing the airborne noise emitted, comparing it with the limits imposed by the LR regulations or, in general, by port and civil regulations. This approach is also a useful tool for estimating the noise level in external passenger areas and therefore also useful for a project aimed at improving on-board comfort.
Sailing at snorkel depth is a necessary but dangerous operating scenario for submarines. The main and straightforward reason is that such an operating condition represents a time of possible vulnerability of the vessel. From a design perspective this condition affects the so-called indiscretion rate, that is exactly the ratio between this time of greater vulnerability and the total operating time. Moreover, when the vessel operates at snorkel depths there are some relevant operations that might be accomplished related to both snorkeling, communications and threats detection. These operations are typically carried out by using a certain number of masts, of slightly different shapes and sizes, that might be used in various configurations.
The proposed study aims at providing some insights into the unsteady hydrodynamics of several submarine masts configurations. The analysis is carried out in terms of behaviors of the developed free surface, considering the non-linear interactions rising among the masts considered. The maximum height and length of the breaking wave generated at the bow of each mast is analyzed in detail both using time instant and phase averaged approaches. Both the near field and the far field unsteady wave patterns are discussed comparing several configurations and focusing on the interaction effects. An analysis of the effect of the size and shape of the masts is also carried out. The computational study is carried out by using an open-source Smoothed Particle Hydrodynamic solver called DualSPHysics, able to exploit the computational acceleration provided by GP-GPU cards. Convergence study and computational effort are discussed too.
Considered from the hydrodynamic perspective, submarines bring many interesting challenges that need to be properly addressed to provide precise information about their performance. Such hydrodynamic performance must be evaluated at least in two main operating conditions, namely when the vessel is deeply submerged and when it sails at snorkel depth. There are relevant differences both in terms of interaction with the free surface and in terms of hydrodynamic itself since the forward speed in the latter condition is typically much lower compared to that of the first scenario. Moreover, submarines used to sail at snorkel depth if they need to accomplish specific tasks, such as communication, that involves the use of surface piercing masts.
The proposed study analyses the opportunity provided by different Computational Fluid Dynamic (CFD) approaches to correctly address submarine performance. In particular, resistance in both deeply submerged and snorkel depth conditions, masts free surface hydrodynamics and maneuvering behaviors are analyzed. Ad-hoc approaches based on in-house developed numerical procedures and open-source software are presented. Different CFD techniques have been used, ranging from Reynolds Averaged Navire Stokes (RANS), Large Eddy Simulation (LES) and Smoothed Particle Hydrodynamics (SPH), according to the particular physics that needs to be simulated. Results from numerical simulations are validated and discussed highlighting the benefits and the drawbacks of each used method.
Cavitation is a highly destructive phenomenon that significantly disrupts the performance of propellers and control surfaces in the maritime industry. Hence, the prediction of forces developed during cavitation, through various numerical techniques, is imperative for the design and operation of maritime vessels.
Since RANS turbulence models have proven to be the most computationally viable option for the fast-paced industry, this work analyses and compares several of these well-established models, including the SST and k-epsilon models modified to account for compressibility effects.
This paper aims to provide insight into the influence of timestep, mesh resolution and turbulence model on the hydrodynamic forces acting on a 2D cavitating hydrofoil, so as to facilitate future simulations.
The interaction of the free surface with either lifting and non lifting, submerged, bodies moving beneath it is of primary interest in naval architecture. Indeed, there are many examples of possible applications such as rudders, stabilizer fins, hydrofoils among the others. The hydrodynamic problem of a submerged lifting body moving close to a free surface presents several complexities that need to be properly addressed in order to achieve a reliable solution. Such a type of problem can be studied and solved in the framework of a potential flow theory, assuming incompressible, irrotational, ideal fluid. The problem can be further simplified by considering that the disturbance of the free surface due to the presence of the hydrofoil are small compared to the water depth and the wavelength, resulting in the opportunity to linearize the free surface conditions around the undisturbed free surface level. The boundary value problem that rises from these assumptions is solved by using an ad-hoc developed Vortex Lattice Method (VLM). The lattice of vortex rings is used to model the effects related to the lift while linear sources are used to simulate the effect of the thickness of the hydrofoil.
The developed method is described and validated by comparison against available experimental data on flat plates and hydrofoils. The analysis then focuses on the convergence properties of the method, especially with respect to the panel mesh used for the free surface discretization, and on a sensitivity with respect to some peculiar operating parameters such as the speed, the depth of the foil with respect to the free surface and the aspect ratio.
This paper presents the investigation of a Pre-Swirl Stator (PSS) possible benefits on the ship powering system. Analysis of the PSS thrust augmentation is performed using the CFD simulations since the effects of turbulence and viscosity are important in the vicinity of the propeller. Direct propeller modelling is employed with the rotative region and propeller geometry present in the fluid domain. Two separate self-propulsion simulations are run, with and without the PSS, giving a clear correlation between the propulsive parameters and operability of the energy saving device. Results are also partially compared to the relevant experimental data. Hydrodynamic simulations are performed by means of open-source software OpenFOAM. The results show the PSS design to achieve a 4.7% decrease in the delivered power to the shaft which proves the design to be beneficial.
Industry 4.0 has favoured the expansion of many technologies where application boundaries are very diffuse. Although some technologies may have very specific applications, they must be implemented as a whole when applied to Computer Aided Design, Manufacturing & Engineering (CAD/CAM/CAE) System (from now on referred just as CAD). The CAD tool stands at the beginning of the design, but it manages many data that must be considered in advance for the further stages of the product lifecycle.
Augmented Reality, Virtual Reality and Mixed Reality are closely related to the Digital Twin and interlaced with Big Data, which are generated by CAD tools and all surrounding solutions, which applies some cloud/edge/fog computing to these data in a merged technology between finite-state machines and Artificial Intelligence (AI) cognitive processes. To perform all these integrations in an agile manner requires a network which support different connections to add specific devices, i.e. Internet of Things (IoT), which can access to the data, creating and modifying them, in a different layer which affects to the basic information layer created by the CAD System in the shipyard. This network should be secure, but also open to allow distributed work, which must be tracked such that all design or process modifications are recorded an open, transparent, trusted and non-modifiable working method for all stakeholders, like: shipyard, engineering offices, classification society and ship owner.
Results of the design should be easily integrated with future manufacturing methods like 3D printing, generating printing orders directly from the CAD model. Shipbuilding phases involve design and manufacturing, but an integrated Industry 4.0 CAD System should also be involved in operation and maintenance phases, i.e. it must cover all the vessel lifecycle end to end, from design to decommission.
This paper briefly summarizes how Industry 4.0 technologies may be applied to the shipbuilding, whether through direct integration or in connected periphery applications.
The paper aims to show the design procedure for a Class-2 dynamic positioning system, from initial conceptualisation to factory assessment test. The approach involves the use of simulation-based design combined with hardware in the loop testing.
This kind of approach involves a detailed knowledge of the investigated ship but gives significant well-known advantages. The main are: the reduction of the design duration, the optimisation of the system performance, the debug of the control logics before the installation onboard, the reduction of the sea trial costs. Finally, the result of this process is a product ready to be installed onboard. Moreover, over the years, the interest of the classification societies in simulation results for certifying such systems is increased.
This study shows both the approach and the results of designing a dynamic positioning system for a Platform Supply Vessel. A custom simulation platform has been developed to have realistic feedbacks of the case-study ship. The DP controller structure, including regulator, force and thrust allocation; have been conceptualised, and then, after the porting procedure, the DP software has been downloaded in the real PCL. Several HIL tests have been carried out to fine-tune the controller parameters. The results show, under different environmental conditions, the respect of the design criteria.
The shipping industry is under increasing pressure to comply with new demanding requirements for exhaust gas emissions. Alternative fuels as well as new technologies need to be developed to meet these goals and reduce Green-House Gases (GHG). This paper investigates ammonia as an alternative fuel for the cruise ship market.
The paper focuses on the regulatory framework (e.g. EU, IMO and Classification Societies) that at present defines requirements for gaseous emissions and design principles of the fuel containment as well as supply systems. Ammonia allows for effective reduction of CO2, but is potentially toxic for human life and the environment. Due to the innovative nature of ammonia as a fuel, the regulatory approach is based mainly on alternative design instead of prescriptive rules.
An applied case – study, with ICE (Dual-Fuel) and electric motors (PEM) as selected standard propulsion system, has been carried out to investigate the impacts of ammonia as fuel on a large passenger ship. The purpose is to evaluate the variation of navigation autonomy, arrangement and weights/stability, considering also specific storage and handling requirements.
Maritime sector forecasts that ammonia will play a pivotal role in decarbonizing ships, since it does not emit carbon dioxide (CO2). Nevertheless, ammonia produces nitrogen dioxide (NO2) burning in ICEs, which contributes to smog and acid rains, being harmful for human health. Combustion also yields small amounts of nitrous oxide (N2O), that is a greenhouse gas significantly more dangerous than carbon dioxide. An option for eliminating harmful emissions is using fuel cell (FC) technology. In this study, a Proton Exchange Membrane (PEM) FC system is considered for the electric energy production on board a 63 m mega-yacht, replacing a traditional Marine Gas Oil (MGO) generating set. Pure hydrogen required for powering the PEM system is produced through an ammonia decomposition reactor and a purification apparatus, to be installed on board as well. Two scenarios are considered: in the first one the PEM provides the hotel loads with 300 kWe; in the second one it guarantees an autonomy of 250 nm with a speed of 8 kn. The effect of such a solution on the general arrangement of the ship is discussed. The main outcomes are that the ammonia processing system for generating hydrogen requires additional power, that is in the range 360-475 kWe, and it is heavier and bulkier than the gen-set. Despite these cons, its installation on board seems to be feasible and it does not involve significant modifications of the original configuration of the mega-yacht. The ammonia-fuelled mega-yacht reduces the original duration of navigation from 11 to about 5 days, nevertheless this value appears still adequate considering the innovative solution at zero emission proposed.
Waterborne transport emissions represent around 13% of the overall EU greenhouse gas emissions from the transport sector and the push for reducing carbon emissions is a top priority for the next decade in the shipping industry. The project ‘Current Direct’, funded by the EU Horizon 2020 initiative, contributes to the direction of decarbonisation and addresses the challenges by designing an innovative and optimised Lithium-Ion battery system. Current Direct aims to develop a containerised energy storage system which enables easy swapping operations to provide a zero-emission source of energy for vessels’ propulsion and auxiliary power. The concept of having a module energy system introduces the need to have a commonly adopted standard interface irrespective of the ship and supporting shoreside infrastructure. Current Direct will be targeting inland waterway & short sea coastal shipping as the conventionally propelled or hybrid vessels in these sectors can easily benefit from battery energy storage systems. The cloud-based Energy as a Service platform developed under Current Direct will pave the way for a sustainable battery swapping business model ensuring the end-users have the clean energy needed, when they need it, at a competitive price comparable to today's fossil fuels. The platform will primarily tackle the optimal charging and discharging scheduling of the batteries, manage the battery supply planning of the vessels, manage the battery fleet deployment between the swapping stations, and incorporate recognized practices of revenue management, thus providing end-users and stakeholders with sustainable swapping services through the EaaS network. The standardisation of this innovative model for swappable energy is also being considered through the development of a unified certification methodology that covers to the containerised battery design, operation , routine verifications, and the ship’s suitability for utilizing such a power source for main propulsion and essential onboard systems.
Authors:
L.Sebastiani, F.Pettinato, A.Pecoraro, L.Carlino (SEASTEMA Fincantieri NexTech)
P.A.Corvaglia, A.Largo, P.Rametta (RINA Consulting)
S.De Giuseppe, F.L.Benvenuto (CO.M.MEDIA)
The “Autonomous Ship” is the new technological paradigm which will drive the trend for increasing automation of ships toward the ultimate goal of remotely-supervised ships able to handle autonomously most of the operational situations. In the recent past, the “MUNIN” EU project established the architectural basis for the Autonomous Ship and since then a few technological demonstrators of the MASS (Maritime Autonomous Surface Ship) concept have been carried out, mostly in the Scandinavian area. Following this lead, SEASTEMA launched in 2019 the MARIN (Monitoraggio Ambientale Remoto Integrato Navale, Naval Integrated Remote Environmental Monitoring) project, co-funded by Regione Puglia within the framework of “Contratti di Programma”.
The objective of MARIN project is to set-up and sea-test a technological demonstrator of the enabling technologies for autonomous navigation. The demonstrator platform is the TESEO I, an experimental trawler vessel realized by NAVTECH and Cantieri Tringali for a previous regional research project in Sicily and based in Augusta. SEASTEMA, through its R&D site in Lecce, is in charge of the auto-remote control of the vessel, including the Situational Awareness System and the Collision Avoidance System, and the overall technological integration. The other partners are RINA Consulting, through its operational site in Lecce, in charge of the realization of an innovative Acoustic Surveillance System integrating a passive acoustic surface array and a thermal camera, and CO.M.MEDIA, a ICT company based in Lecce, in charge of the operational demonstration of a tethered aerial drone acting as additional optical sensor to provide a BEV (Bird Eye View) of the vessel surroundings for “geofencing” and object identification. Preliminary tests of the separate system components have been carried out in the summer and autumn of 2021 and the final operational tests will be carried out in the summer of 2022. The paper presents a technological overview of the research project and its achievement, including the preliminary results of the 2021 tests.
Modern automation systems on-board ships perform a variety of complex tasks, offering a great range of options for optimizing ship operation. Interaction between on-board computer-based automation systems and between on-board systems and remote monitoring or control stations has become a key factor for successful and economical ship operation, yet demanding high integration, connection, communication, and control of the interacting components.
Complexity and interconnection of computer-based systems on ships however open the possibility for cyber-attacks to affect personnel data, human safety, the safety of the ship, and threaten the marine environment.
It is then necessary to safeguard ships and shipping in general from current and emerging cyber threats adopting countermeasures to make ships cyber resilient.
With the advent of unmanned and autonomous ships (Maritime Autonomous Surface Ships - MASS), several tasks and functions traditionally carried out by humans are becoming blurred. While in conventional ship operation seafarers play a role in all functions and interact with ship’s systems and the environment, MASS technologies bring changes in how tasks are carried out and how duties and responsibilities are assigned.
Partially or totally replacing the human element e.g. in decision making processes and/or interaction with traditional automation systems and the environment, MASS technologies bring new specific cyber-resilience and safety challenges that need to be addressed and require new approaches to risk management.
In this article, minimum requirements for cyber resilience of traditional ships are described, based on the work carried out by the International Association of Classification Societies (IACS) and new cyber-related challenges posed by MASS technologies are outlined.
Autonomous vehicles represent the new frontier in the marine ecosystem’s analysis and monitoringas they extend human abilities at sea. Their capabilities are strictly related to:
• the algorithms that provide their autonomy;
• the complex and detailed CONOPS needed to be developed and defined in order to comply with all the operative and environmental scenarios to which the platform will be faced with
• the innovative and holistic design process for defining robust and reliable data acquisition/transfer, intelligent systems-of-systems for self-diagnostics for operational safety and interactive deep learning processes.
This paper presents the preliminary activities undertaken for the research project called SUNMARE (Surface UNmanned multipurpose research MARine vEhicle) which aims at the development of an innovative fully autonomous platform for marine, oceanographic, lacustrine, and submerged/semi-submerged cultural heritage monitoring/measurements.
SUNMARE is a modular ship comprising of a mother unmanned ship and a smaller Autonomous Underwater Vehicle (AUV). The AUV can detach and reconnect autonomously to the mother ship to perform independent tasks. Some of the innovation relies on two fundamental characteristics:
(i) both vehicles can be easily disassembled and transported in standard ISO containers, to increase their field of use;
(ii) the AUV is launched and recovered with a LARS, which ensures the success of the operation in complete safety.
The mother shipmust possess the following fundamental design requirements:
• modularity and disassembly of the vehicle
• possibility of embarking an ISO10 container dedicated to scientific and technological research
• an innovative and sophisticated LARS.
The general architecture of SUNMARE is presented with the innovative high efficiency propulsive solutions selected, as well as a detailed risk analysis, the definition of the requirements and technologies dedicated to the “autonomization” of the vehicle and the preliminary numerical simulations concerning the “autonomous self-drived dynamic connection” of the vehicles and the basic operation of the LARS system controlled by an ad-hoc designed control algorithm.
A numerical model of a dual-chamber Oscillating Water Colums (OWC) Wave Energy Converter (WEC) is built through the DualSPHysics software. This code is based on the Smoothed Particle Hydrodynamics (SPH) model, a Lagrangian meshless method where particles represent the flow, interact with structures, and exhibit large deformation with moving boundaries. A one phase approach – only water - is chosen in order to limit the computing time, as it increases with the total number of particles, and the power take-off (PTO) of the system is modeled by the force applied by a vertical linear spring link on a floating plate inside the chamber. The force formula and coefficients are described, discussed and tuned for various wave states to optimize the model. Validations against experimental data received from previous tests in wave flumes are performed. The floating plate heave of the numerical model is compared with the experimental free surface elevation. The result analysis establish that DualSPHysics can be considered as a reliable tool to model a fixed OWC WEC. Subsequently, this model will be mimicked and adapted for a floating dual-chamber OWC WEC performance.
In the last years, an increasing attention has been devoted to ships Underwater Radiated Noise (URN), with the progressive interaction of guidelines by international organizations such as IMO, Classification Societies voluntary notations, limits and incentives in specific areas. In this context, a large effort has been spent in the study of cavitating propeller noise since it represents the dominating noise source on ships. UNIGE is currently involved in the EU-funded LIFE-PIAQUO project, in which the main activities are related to propeller design by optimization, onboard cavitation detection during operations, noise mapping. The present paper reports motivations, aims and achievements of these activities in the first half of the project.
In early 2020, sea trials carried out in some interisland high-speed boats in Galapagos confirmed the need to improve the comfort of the passengers during those trips. Results from those tests showed very high levels of vertical acceleration which, according to ISO 2631 standard, provoke high negative effects on the passengers, as was directly observed. This project aims to design at conceptual level a fiberglass reinforced plastic high-speed boat including flaps, with minimum vertical acceleration while also considering the boat resistance. The design variables considered were length, beam, longitudinal position of the center of gravity, hull deadrise angle, flap deflection angle and its chord. In addition, the constraints considered were dynamic trim angle for porpoising, length-beam ratio, metacentric height, freeboard, and required area for passengers. A multi-objective optimization method available in OpenPlaning, an open-source Python-based framework, was employed. The resistance was evaluated with a combination of semiempirical formulations with a prismatic hull assumption that included the effect of waves, whisker spray and flaps; while the vertical acceleration was estimated with formulations from lab tests based on significant wave height. To estimate the Pareto front, the NSGA-II (Non-Dominated Sorting Genetic Algorithm) optimization algorithm is chosen considering the complex relations and number of design variables. First, the benefits of including flaps to reduce the boat planing angle, and as result a reduction in the motion acceleration were confirmed. Also, results show that sea performance of the boat is highly affected by LCG position, deadrise angle and angle of flap. The combination of these parameters that helps to reduce the objective functions are identified. Finally, the estimated Pareto front identifies a set of solutions, which shows that the acceleration could be reduced by up to 19% and the resistance to advance of the boat by 5% with the increase of some design variables.
The aim of this study is to experimentally investigate the cavitation erosion on the blade root of four blade controllable pitch propeller. Experiments are carried out on a model scale propeller considering two different pitch settings of propeller. The soft paint technique is used to study cavitation erosion, exploiting also two standard cameras and one high speed camera to study the damage patterns and cavitation dynamics, respectively. Standard cameras are placed on the top of test section in order to periodically monitor the occurrence of damages on the layer of paint. The high-speed camera has been used instead to analyse bubble dynamics and identify potentially erosive phenomena. Different camera configurations have been considered to get detailed insights of bubble dynamics on pressure and suction side of propeller blades. The paint tests results have been analysed together with high-speed videos, showing a remarkable agreement between the occurrence of damage and cavitation collapse phenomena. The results demonstrated three regions on the propeller blade with high risk of erosion: (1) suction side of blades, around mid-span, showed pitting damages due to sheet cavitation collapse, (2) suction side blade root showed significant damage pattern due to single bubble as well as bubble assembly collapse, and (3) pressure side blade root showed slight damage pattern due to spherical bubble collapse. In addition, four different cavitation bubble structures have been identified in the present study: sheet cavitation, streak cavitation, spherical bubble cavitation, and twisting bubble cavitation.
The aspects related to the vibrational behaviour of the ship are significant for issues relating to possible fatigue stress on structure, heathy and onboard operators’ comfort reasons. Nowadays, this is even more significant due to the need of keeping the hull weight that leads to plan increasingly lightweight and less rigid structures and therefore more likely to experience vibrational and vibro-acoustic noise phenomena.
In this field, it is substantial the use of the Transfer Path Analysis (TPA) technique which is an experimental methodology that allows to study the phenomena of transmission of the vibration energy also to physical systems characterized by high levels of complexity with several sources working simultaneously on the same field.
Traditional techniques do not allow the spatial mapping of energy paths which remain unknown also after the acquired data elaboration. Otherwise, TPA allows to identify the paths and contributions traceable to vibration sources.
During applied research, in a first approach applied on a naval cruise, three main sources onboard have been considered: the propeller and the electric and diesel engines.
The application of Transfer Path Analysis allows to identify the vibration energy transmission paths and to verify that no other significant path is left out. These are the transmission ways through which the vibration is transferred from the source to the receivers: in the case of the engine and the propeller both transmission paths start from the foundations and arrive to the cabins through decks and main\secondary structures. Sources, paths and receivers were properly characterized experimentally for the technique application.
The operative calculation of the vibration response corresponding to the targets, allowed a validation of the method through a comparison between the calculated vibration and the full execution of the procedure.
The development of this methodology allowed to refine the forecasted calculation methods of the vibrations and the structural noise in the planning phase, and to perform refined experimental measures to solve issues related to structural noise propagation and to vibration onboard.
The International Maritime Organization has formally approved, as recommended guidelines, the methods and procedures of the Second Generation Intact Stability Criteria (SGISC). These criteria introduce the concept of dynamic stability in the intact stability assessment of ships and define the failure modes that might occur to a ship that navigates in harsh sea conditions. This paper focuses on surf-riding and broaching phenomena in stern-quartering seas, with the objective of analyzing the characteristics and the potential of SGISC risk assessment in the ship design.
The risk-evaluation criteria of surf-riding and broaching were followed through Level 1, Level 2 and Direct assessment of SGISC. Two different hull designs were considered, a fast displacement ship and a high-speed V-bottom, hard chine hull. Time domain simulations were performed using a time domain potential flow boundary element method. A detailed definition of broaching was used to detect the event occurrence in irregular waves, and the results were compared with failure mode definition of SGISC concerning the roll and lateral acceleration safe limits exceedance. The SGISC were also employed in the attempt to evaluate the different failure mode risk assessment due to different stern appendages configurations of the two hull designs with respect to broaching and surf-riding.
One year later the finalization of Second Generation Intact Stability criteria (SGISc), there is still the need to validate the robustness and consistency of these criteria as indicated by IMO. The stability failures addressed by SGISc take into account the dynamical aspects in relation with the actual seaway conditions which may affect the ship stability performances, i.e. they focus on the effects of hull and wave interaction. Vulnerability to a stability failure cannot be always fixed acting only on the vessel design; also operative considerations are needed in order to reduce the risk level during the navigation. For this reason, the multilayered approach has been adopted: it consists of three assessment levels, with no specific reference to the operational profile, and a further level suggesting which measures are to be adopted for a safe ship routing in specific sailing conditions.
After an introduction to SGISc, an application will be carried out. A Ro-Ro pax ferry has been selected as subject of this investigation. Vulnerability levels (i.e. Level 1 and Level 2) are applied in order to assess the compliance of a modern representative Ro-Ro ferry. Moreover, a study about how the environmental conditions and operative parameters may affect the results is undertaken considering different scenario, such as the geographical area or the ship service speed.
In modern versions of the Directive 2009/45/EC and in some rules of classification societies, for example Registro Italiano Navale, options for the designation of the navigation area for passenger ships are proposed.
Fast ferries carry not only Ro-Ro cargo, but also a large number of passengers and therefore belong to the type of passenger ships. Considering the high speed of these vessels, up to 40 knots and the short distance from the port of refuge during the voyage, liferafts are the main life-saving appliances on board the high-speed ferry. By the rules of the International Code of Safety for High-Speed Craft, the time for rescuing people from aboard a high-speed passenger ship is limited. In this article, the characteristics of the rescue boat for rescuing passengers from the ferry will be determined. The worst case for a rescue craft at moving against a wave, with a typical wave height for this area, will be considered. The permissible value of the width of the navigation zone will be determined, taking into account the survival time of a person at the water temperature of a given area.
When designing a high-speed passenger ferry, it is very important to know at an early stage of the project about a possible decrease in speed when moving on a sea wave. This speed reduction can be predicted at an early stage of the project based on the data on the wave parameters in the region and the characteristics of the fast ferry.
To solve these problems at the first stages of the project, for a “One digit” assessment, Energy Wave Criterion (EWC) will be used that takes into account the kinetic energy of the vessel and the energy of the wave.
Keywords: Energy wave criterion •(EWC), monohull fast ferry, navigation area.
Reducing fuel consumption and carbon emissions are two of the main concerns of the maritime industry. Among the available energy-saving devices or solutions, one of the most promising is air lubrication which has been extensively studied in the last decades, especially for the drag reduction on displacement hulls.
Compared to displacement hulls, the planing and semi-planing hulls have different hydrodynamic behaviour since the resistance and running attitudes are significantly influenced by the hydrodynamic component of pressure and the hydrodynamic pressure can influence the effectiveness of the air lubrication solution on planing hull.
This study proposes an air lubrication solution for a planing workboat combining the airflow injection with an air cavity solution obtained by a DIS (Double Interceptor System) device implementation.
The results of the experimental and CFD simulations campaign with natural and forced airflow injection combined with a cavity generated by DIS are presented. The drag resistance improvement and the airflow details have been analyzed by inducing a systematic variation in the airflow rate.
The increase in the size and mass of ships reduced transportation costs but, it created new problems associated with operational aspects of large ships. For instance, further development and testing is required to improve the berthing process of large ships under various environmental conditions. Numerical models properly developed, validated, and calibrated are a valuable tool in the design process of berthing structures. The validation process of such models requires reliable data to be collected in situ or measured in scale-model tests. These tests do provide relevant information and results about berthing processes. The goal of this work is to assess and compare berthing forces obtained with a 1:100 scaled physical model with the ones obtained with a numerical model.
The physical tests were conducted in an area of 4 m x 4 m of a 22 m x 23 m (width x length) tank of the Ports and Maritime Structures Division of the Hydraulics and Environment Department of the National Civil Engineering Laboratory (LNEC) using a scale model of an oil tanker. Different loading conditions, speeds and angles of approach were tested. Ship’s velocity and heading were recorded using an Optitrack® multi-camera motion capture system, the impact forces were registered by four force sensors and a Quantum MX data-acquisition system with CatmanEasy® DAQ Software.
The numerical modelling was performed with the MOORNAV module of the software package SWAMS – Simulation of Wave Action on Moored Ships, developed at LNEC. The MOORNAV module includes two numerical models, namely WAMIT and HYDRO/BAS, which are able to estimate ship movements and forces on mooring lines and fenders, using time-domain formulations.
This comparison allows a better understanding of the variables related to the ship and the fenders, namely the magnitude of impact forces on fenders and their sequence. Furthermore, the suitability of numerical modeling of ship impacts on fenders can be assessed and the validated.
