Ebook: Technology and Science for the Ships of the Future

About NAV

The first Conference took place in 1974 as “Convegno Scientifico del Gruppo Automazione Navale e Problemi delle Grandi Navi” (Scientific Conference of Marine Automation Group and Large Vessels Issues), to be held every two years under the patronage of Technical Naval studies Centre (CETENA) and Italian National Research Council (CNR).

In 1984 the cooperation between CETENA and Marine Technical Association (ATENA) led to rename the conference as NAV spreading the topics also to purely technical field, originally covered by ATENA national conferences. Since 1994 the NAV conference is held every three years. As the most important Italian forum for scientific and technical maritime community, it attracts specialists from all over the world.

The 19th Conference (NAV 2018) is finally back in Trieste, after 30 years of absence. For this purpose, a Committee of Honor has been established, including personalities representative of Italian maritime excellence. An international Scientific Committee, composed of members of international academic institutions and relevant industry sectors, ensures the scientific quality of the conference under the guidance of the chairman, Professor Alberto Marinò (University of Trieste).

The previous editions: Rome (1974), Naples (1976), Trieste (1978), Genoa (1980), Naples (1982), Venice (1984), Palermo (1986), Trieste (1988), Ancona (1990), Genoa (1992), Rome (1994), Sorrento (1997), Venice (2000), Palermo (2003), Genoa (2006), Messina (2009), Naples (2012), Lecco (2015).

About ATENA

In 1947 ATENA (Associazione Italaiana di Tecnica Navale) was established in Genoa under the initiative of a group of Italian naval architects and marine engineers. The principal aim was to extend the initiatives of the Collegio degli Ingegneri Navali e Meccanici in such a way to stimulate the discussion on ship design and maritime industry between the Italian specialists in this sector.

In February 1948 the first Technical National Conference was held, collecting contributions from the most representative personalities of the national maritime sector, including professional naval architects and marine engineers, professors, researchers, shipowners and insurers.

Since ATENA's founding, its members have been providing high level contributions to research, ship design & construction and the shipping industry. Besides, a primary focus is given to other actual and relevant topics such as maritime safety and environmental issues.

As part of the maritime industry acting in a global market, ATENA is also spreading its vision worldwide, opening up its conferences and events also to international professionals.

The Suez Canal is an artificial sea-level waterway connecting the Mediterranean Sea and the Red Sea through Egypt. Tolls paid by the vessels passing through the Canal represent an important source of income for the Egyptian Economy. The current philosophy of SC tolls is based on calculating the tolls as a percent of the vessels' Suez Canal Net Tonnage. The current research recommends making use of the recent international regulations enforced, particularly the Energy Efficiency Design Index (EEDI), and the timely published international indices for the charter rates and bunker prices for calculating the SC tolls on a case by case basis to respond to the market fluctuations, maximize SC income, and increase potential customers. Bulk Carriers are taken as a case study to compare between the enforced tolls philosophy and the savings calculated using the suggested method, and to study the relevant importance and sensitivity of the parameters used in the calculations in order to reach a base for developing a new toll policy.

The accurate prediction of wave-induced forces and moments on a hull operating in severe weather conditions plays an important role in assessing ship structural strength. For ships prone to large variation of the submerged hull in wave, wave-induced loads could be influenced by the development of parametric roll. This concept is based on the evidence that the combination of all the ship rigid body motions could lead to larger loads on the hull, (such as inertial, restoring and Froude-Krylov loads), and thus to unexpected internal forces and moments on the hull structures. In this paper, we aim at a fair assessment of the variation of the internal loads in waves on ships, in presence of parametric roll resonance. A numerical model is developed and applied to simulate ship dynamics in waves and to estimate the corresponding wave-induced loads on ship structures. The applications are meant to assess the accuracy of the developed method. Particular attention is given to the horizontal bending moment and to the torsional moment. Comparison with reference design loads are presented, aiming at disclosing the severity of parametric roll phenomenon on the ship structures.

The paper presents an original variable layout steam plant for the Waste Heat Recovery (WHR-VL) from marine dual fuel (DF) engines, designed considering the different exhaust gas stack temperature limits, depending on the engine fuel type: generally no less than 160°C for diesel oil and without limits for natural gas (NG). Using diesel oil, a single pressure superheated steam plant configuration is adopted, while a dual pressure system is proposed for the NG fuel mode of the engine. In both WHR-VL plant layouts, the produced steam is mainly delivered to a steam turbine for the ship electric energy production, while a smaller amount meets the ship thermal loads. Starting from data of a marine four stroke DF engine, the WHR-VL steam plant components are sized and optimized through a mathematical code, according to a numerical procedure described in the paper. The WHR-VL plant data and performance, for different engine fuel modes and loads, are compared with those of a more traditional WHR single pressure steam plant, developed and optimized for the waste heat recovery of the same dual fuel engine.

The International Maritime Organization (IMO), through its Maritime Environmental Protection Committee (MEPC), has been carrying out substantial work to provide the fundamental conditions for the reduction of greenhouse gas emissions from international shipping since 1997, following the adoption of the Kyoto Protocol and the 1997 MARPOL Conference. Many documents, issued in this respect, are dedicated to different types of vessels. More of the requirements and regulations for establishing of efficiency criteria are based on commercial activities of the vessels and respective fuel consumption. There is the big difference between offshore vessels and all other vessels. Offshore shipping industry has another criteria for effective fuel consumption. As longest as the job is with very high risk Safety is with high priority. The offshore industry try to find another way and means for implementation of MARPOL Annex VI requirements. The article summarizes Classification Societies requirements regarding offshore vessels. The requirements are compare with IMO Resolutions in this field and conclusions are made. The authors has made proposals to education system which are related to STCW Convention Code, Part B.

The European Inland Waterway Transport (IWT) is a viable and effective alternative to road and rail transport of persons and goods on the European network. Currently, the IWT is less exploited than the ‘traditional’ transport despite the European inland waterway network spans more than 29000 km and includes over 400 important ports and terminals. The design of inland waterway vessel is heavily affected by the environmental constraints and the Rule framework. About the latter, in the last few years several organizations played an important role in the definition of the Rule framework in Europe: the United Nations Economic Commission for Europe (UNECE), the European Union and various local area commissions. The tendency of international regulations is to make inland waterway decarbonised by reducing pollutant emissions through ships with zero-emission propulsion. Moreover, the design is also affected by environmental constraints like width and depth of the canals, air draft, etc. In this paper, a ‘new concept’ for inland waterway vessel, which considers the modern national and international regulations and the environmental constraints, has been defined. A case study and the results obtained have been analysed.

Marine engine industry is in the quest for continuous improvement of efficiency and performance. Currently, all components involved in marine engine construction are made in metallic alloys. In order to reduce costs and weight, new materials for non-structural components must be identified. The introduction of new materials, e.g., nano-engineered thermoplastic polymers (NETP), will allow additional benefits due to drastic weight reduction and simplified maintenance and inspection operations. Advancements in NETP design and application in marine engine industry relies on computer-assisted multiscale material design (CAMMD). Indeed, by advanced CAMMD techniques, the structure of NEPT materials can be tailor-fitted to achieve the expected performances required by specific, advanced applications. Since the introduction of plastic materials in the construction of non-structural components for marine engines constitutes an element of great innovation, a specific rule framework must be defined yet. In this paper, starting from the analysis of the regulatory context currently used for metallic alloys a certification procedure is proposed and applied to a case study related to the cylinder head cover of a four-stroke marine engine. In particular, the mechanical properties of a new NETP material designed by CAMMD have been verified trough a finite element simulation carried out on the relevant model.

The number of cruise ships sailing is growing constantly worldwide, driven by a continuously increasing number of passengers. Higher attention to this ship segment runs together with more complex energy systems installed on board due to the needs of improving energy efficiency and reducing operational costs. For these reasons, ship Owners and Shipyards are involved in the design of power plants and energy management systems that ensure lower fuel consumption and compliance with increasingly stringent IMO regulatory requirements on emissions. To respond to these needs, we hereby introduce LESS (Low Energy Ship deSign tool), a simulation environment developed to support the designers to choose among different propulsion/hotel plants solutions since the early stage of the ship design. The software allows analyzing the energy performance of different plant layouts and system components and eases the integration of energy recovery solutions. In particular, the library of components includes heat recovery packages such as Organic Rankine Cycles (ORC) systems to reduce “non propulsive” power demand.

In this work, we address the use of Hardware In the Loop test rig for renewable energy application. Such test rig is designed to evaluate the performances of the wave harvesting system called ISWEC. The ISWEC is a floating, slack-moored, gyroscopic Wave Energy Converter. The full-scale prototype has an electric-mechanical Power take-off (PTO) composed by a gearbox and a brushless torque motor. The system is torque controlled to keep the gyroscope in the desired position range and to obtain maximum productivity. In order to obtain this, two different control methods are under study: a proportional-derivative (PD) law and a passive control method. The PD control law regulates the torque on the PTO providing a stiffness term to recall the gyroscope in the vertical position and a damping term to extract power. In this configuration, the PTO performs the recall effect, resulting in an increase of the torque load. To overcome such problems, the use of an eccentric mass to provide the stiffness term is analyzed. The experimental tests demonstrate the reduction of the PTO torque, justifying the gap in the system productivity provided by the passive control as assessed with the numerical model.

The worldwide effort on the environmental issue in the maritime field has led to always more stringent regulations on greenhouse gas emission (GHG). In this perspective, the International Maritime Organization has developed regulations intended to increase the ship's efficiency and reduce GHG emissions both in design phase, through the introduction of an Energy Efficiency Design Index (EEDI), either in management phase, adopting the Ship Energy Efficiency Management Plan (SEEMP). In this challenging perspective, several approaches and technologies adopted in land-based engineering can also be advantageous for marine applications. This is the case of the Distributed Energy Resources (DER) solution applied in land-based microgrids, which increases both the system's efficiency and reliability. This work is primarily focused on methodological aspects related to the adoption of a DER solution on-board cruise ships, with the integration of different energy sources in order to pursue a more flexible, reliable and sustainable management of the ship. In this context, another engineering best practice developed for land-based applications that is further investigated in the paper is related to the on board thermal energy recovery issue, revisited due to the implementation of the DER solution.

Over last decades, due attention was paid to development of new stability criteria, especially probabilistic rules for damage stability, strongly influenced by the loss of many ro-ro ships in last decades of past century. In the last years, also a revision of intact stability code started and proposals have been implemented introducing stability in waves. These proposals deal with the equilibrium of a ship in regular waves to evaluate initial stability (GM) as well as righting arm curve in waves (GZ). This paper is not intended to critically review the present and proposed initial stability code, but is limited to assess how expected behavior of intact ships in waves is affected by accuracy in computer programs for assessing actual hydrostatic properties. An updated computer code, designed for onboard application and based on 3D pressure integral, has been developed and tested for a ro-ro ship. Then a comparison between hydrostatic and Airy effective waves has been carried out to analyze the relevance of differences between the two correspondent pressure fields affecting the equilibrium position and hydrostatic properties of the ship. It is demonstrated that these differences appear relevant beginning from sea state 4.

The evaluation of the safety state of the ship in a generic operative or emergency condition is a very complex issue due to the huge number of attributes involved in the problem, uncertainties of their values and assessment of their mutual importance. The safety of the ship shall be presented in a simple and immediate manner in order to provide a useful decision support to onboard personnel. That is why a hierarchical risk assessment procedure has been developed selecting a set of attributes which are grouped in criteria and sub-criteria. The attributes are fuzzified and combined in order to obtain a risk index for each sub-criterion and criterion. The mutual importance of criteria, sub-criteria and attributes is assessed by means of a Fuzzy Analytical Hierarchical Process (FAHP), which rationally incorporates and treats the experience of masters and officers collected by a survey. This process allows summarizing experience and proficiency into a decision support system devoted to increase ship safety, while providing an interesting representation of the onboard perception about risk and its main causes.

Nowadays, fuel consumption reduction is a primary concern in order to minimize operative costs and emissions during navigation. On this purpose, ballast management play an important role, in order to find the best configuration for ship navigation. An optimal ballast water distribution ensures to find a floating position having the minimum fuel consumption while assuring the fulfillment of rules requirements related to strength and stability. Since ships are operating also in adverse sea state condition, optimal ballast conditions should be found also for service conditions, considering the impact of added resistance due to waves on the propeller and consequently to fuel consumption. Within an emergency decision support system, an optimum ballast system has been developed satisfying the above mentioned requirements. In order to assess the optimal ballast allocation in a fast and accurate way, the equations are linearized and solved by means of pseudo inverse matrix. The target of this process is to find for a defined set of ballast tanks the level, or rather the volume, of water to reach the optimum floating position. The procedure has been tested on a reference ship and the results are here reported and described.

The recent trend of marine industry towards more efficient and versatile ships and lower emission has increased interest in hybrid solutions. However, the spread of this technology has been limited by several factors both economic and technical. Among these, a recurrent issue is the sizing of the Energy Storage System (ESS), which is strictly connected to the vessel typology, its operation and its control system. This paper presents an algorithm, developed within Wärtsilä Italia SpA, for the extraction of sequential operating modes from data recorded on board the vessel, in order to properly design a feasible ESS. The paper shows a technical economic analysis carried out on a small cruise vessel in order to identify competitive hybrid solutions compared to traditional configurations (engines running on conventional fuel or Liquid Natural Gas). Finally, the paper compares two case studies of a small vessel powered only by fuel cells (in place of conventional engines) and batteries, in order to prove the potential benefits derived from such innovative technologies with different operational profiles, also in hybrid mode.

This paper describes U-SWATH an innovative Unmanned Surface Vehicle (USV), based on a Small Waterplane Area Twin Hulls (SWATH) design, developed by CNR INSEAN and ISSIA for institutional research purposes. The vehicles is composed of a wide flat deck covered with solar panels which connects two torpedo hulls. The hulls are composed of modular and interchangeable sections that can be outfitted with different payloads, equipments, propulsive or manoeuvring elements. The propulsion system is based on ad hoc electrical azimuthal thrusters. The solar panels covering the wide U-SWATH bridge are used for recharging the batteries supplying power to the vehicle. U-SWATH is multitasking and the goal of the designers was to develop a cutting-edge autonomous multi-purpose platform for carrying out research in the marine and the maritime fields.

In recent years, the MVDC distribution has been proposed as a viable solution for the redesign of the shipboard Integrated Power System (IPS). Indeed, there are relevant advantages promised by the innovative DC concept, among others a desirable reduction in the electric power system size. For providing a virtual proof-of-concept of this technology, parametric and interactive 3D models can be developed by a new Computer System Integrator (CSI) software. The latter may give the possibility to quantify the expected onboard benefits (i.e. increase of pay load) already during the early-stage design, thus opening interesting evaluation since the very first stage of ship design. By exploiting the capabilities offered by the integrated design methodology, a comparative analysis between a conventional MVAC electrical distribution and innovative MVAC/MVDC hybrid systems is performed in this paper. In particular, a significant Main Vertical Zone of a large cruise ship is modeled by the CSI software for providing a detailed comparison (volumes/weights) among the power distribution architectures (MVAC vs hybrid MVAC/MVDC).

The prediction and reduction of underwater noise is commercially, militarily and ecologically a very critical issue for maritime industry. Machine noise, propeller noise and flow noise are the main components of underwater noise for submerged bodies. Especially at high flow velocities, flow noise becomes dominant source of underwater noise radiated from these bodies. In this paper, the effects of the fluid temperature and salinity of the fluid on the underwater flow noise are investigated, numerically. A circular cylinder is selected for the validation studies of the noise model used in the acoustic analyses. The flow characteristics are obtained by solving governing equations of fluid using Computational Fluid Dynamics (CFD). The turbulence is modelled by using SST k-ω turbulence model. The Ffowcs Williams and Hawkings (FW-H) noise model is applied to predict the sound pressure levels at the receiver points defined various locations, numerically. The monopole, dipole and quadrupole sound sources are taken into consideration for acoustic analyses.

Safety is of paramount concern to passenger ship owners and integral to their reputation. For this reason, passenger ship owners are aiming for safety standards well beyond the statutory requirements. The current methods for assessing ship survivability following hull breach and subsequent flooding, adopt a simplified application to define a complex issue leading to uncertainty and over-design. This study uses high fidelity deterministic Computational Fluid Dynamics (CFD) analysis in order to explore the shortfalls of the current design guidance such as SOLAS. A number of flooding scenarios are modelled on a cruise ship at full scale for calm and rough seas.

In the present work a hybrid methodology is used to evaluate the hydrodynamic noise generated by a marine propeller in open sea condition. The hydrodynamic field is computed using Large Eddy simulation under the assumption of incompressible flow field; the acoustic field is reconstructed by applying the advective Ffowcs Williams and Hawkings equation. For the hydrodynamics, we use the dynamic Lagrangian model for the closure of the subgrid-scale stresses and a wall-layer model to skip the resolution of the viscous sub-layer. We consider a propeller well studied in literature for a single value of the advance ratio. A grid of about 6x106 cells is used for reproducing accurately both the stresses over the propeller and the wake, the latter responsible of quadrupole noise. The equations are solved in a fixed-to-the-body frame of reference. The different noise generation mechanisms are investigated separately. Thickness and loading terms related to the propeller shape and velocity, provide significant pressure disturbance in the near field. The quadrupole noise component is obtained by integrating over an external permeable surface. Its contribution is investigated in relation to the presence of vortex persisting in the wake.

Noise emissions from various transportation modes became in recent years a major concern for environmental and governmental agencies due to their impact on the community. As a result, experimental campaigns and studies have been directed towards the analysis and control of the main noise sources. Only a few analyses, however, have regarded noise exposure due to port activities. In this paper, the focus is on airborne noise emissions from a ferry ship. At first, the main onboard noise sources were identified in terms of their nature and location. Secondly, sources data on the main sources were derived, based on onboard measurements of the ferry berthed in the port of Naples. A geometrical 3D model was created, including all bodies present in the acoustic field of the surrounding area. Finally, by post processing, the consistency between actual acoustic field and numerical model results was checked.

The aim of this research activity is to predict the low-cycle fatigue life of welded joints used for ship structures, applying two methods: the effective notch strain approach and the structural strain approach. The first method was applied performing elastic-plastic finite element analyses (FEA), using different cyclic stress-strain curves for base material, heat affected zone and weld metal, while the second method is mesh insensitive for applications in high cycle fatigue regime and has recently been adapted for applications in low cycle fatigue regime. The geometry used for the first method was acquired by means of a 3D scanner. Effective notch strain results and structural strain results were used to predict the low cycle fatigue life.

Aluminum superstructures and steel hull connections are of fundamental importance in ships. This study regards the buckling analysis of explosion welded joints, made of three layers (ASTM A516 low carbon steel, pure aluminium, A5086 aluminium alloy) and used in ship structures. Experimental tests were carried out on explosion welded specimens. The Digital Image Correlation technique was applied during the tests for the detection of displacement and strain fields. A theoretical analysis, considering the different materials was also performed. Furthermore, a non-linear finite element analysis, considering the different mechanical properties of the explosive welded joint, was performed and was validated by means of the experimental results.

Optimization of modern hulls when moving in a seaway puts new demands on the computational methods used. Nonlinear effects become important for wave loads and added resistance in waves in presence of large motions. The purpose of this paper is to present a method which aims to fill the gap between RANSE methods and partly nonlinear panel methods. The method solves the fully nonlinear free surface time-domain potential flow problem including a hull undergoing rigid body motions. Nonlinearities under the hypothesis of potential flow are taken into account, i.e. higher and lower frequency components, hull shape above calm water line and interaction between incoming, radiated, diffracted, reflected and ship generated waves. The potential flow method alone cannot handle roll motion since roll is dominated by viscous effects. Two methods to include roll damping within the potential flow code are used: the first one obtains roll damping coefficients through inertial and geometric characteristics of the ship. The second one uses model test results. Numerical results using both methods are compared. The code has already been tested in head seas. In this paper, numerical simulations of roll decay and roll motion in beam sea are compared to model test results.

Autonomous Underwater Vehicles (AUVs) are offering new capabilities for a wide range of military and civilian applications. The interoperability of heterogeneous AUVs with different skills is critical to accomplish such complex tasks. Indeed, the proliferation of AUVs with their own mission control interface and communications protocol makes it difficult to operate them within operational experimentations, which requires joint management and coordination. This problem was approached in the preparation of the ASW-ODC17 (Anti Submarine Warfare - Operational Deployment of Concepts) sea trial, which, among its objectives, aimed to demonstrate the interoperability of an external AUV (the Folaga WAVE) within the CMRE heterogeneous robotic network during a NATO operational exercise in ASW. The different hardware and software architectures were integrated by configuring an asset of the CMRE network (a gateway buoy) to act as a bridge between the two robotic systems. All the AUVs were successfully operated during the joint NATO exercise through the same mission control station, unconcerned by differences in acoustic modems and robotic middleware.