Ebook: HSMV 2023

This book presents the proceedings of the 13th International Symposium on High Speed Marine Vehicles, held from 23 to 25 October 2023.

The High Speed Marine Vehicles Conference has more than 30 years history since the first Conference held in Naples in 1991. Since then, it has been an opportunity to present and discuss developments in the design, construction and operation of high speed marine vessels.

The Symposium is addressed to academics, research organizations, industry, government agencies, certifying authorities as well as to designers, operators and owners who contribute to improved knowledge about the high speed vessel. For the present edition, more than 40 abstracts have been submitted and, after a review process, 27 papers have been included in this book.

Thanks are due to the Scientific Committee who shouldered most of the responsibility for reviewing papers and providing constructive comments to improve their quality.

My personal thanks to Professor Antonio Fiorentino, founder and Chairman of HSMV, for sharing his invaluable knowledge and experience and inviting me in this role.

Ermina Begovic

A time-domain strip method, in the Zarnick tradition, is examined for validity in simulating warped, non-prismatic, planing hulls in calm water, regular and irregular waves. Results on simulations of model experiments are shown. Validity is exemplified by direct comparison by experiment time-series and the simulated correspondence. The 2D+t strip approach is concluded valid for simulating the examined experiments.

Due to the violent slamming, small and fast RHIB (Rigid Hull Inflatable Boats) are exposed to high accelerations. One of the challenges when designing a RHIB is to reduce these accelerations. This paper proposes a method to assess the slamming behaviour of a RHIB in the preliminary design stage, i.e. when the hull forms are not yet determined. This method couples a non-linear 6DOF time domain simulation tool to the visual programming language Grasshopper^®. The time domain tool was used to predict the rigid-body dynamics of the RHIB in different sea states; Grasshopper was used to automatically generate a series of parametrized RHIB hull 3D surfaces, by systematically varying the LP/BPX ratio, the average and longitudinal distribution of deadrise. The results of the simulations highlighted the optimal designs that showed the lowest level of slamming accelerations. This approach has the advantage that any geometrical details of the RHIB can be parametrized and tested, without the need to rely on certain hull forms as with systematic series. Moreover, a large number of scenarios and hull characteristics could be simulated at the cost of modest computational resources.

This paper uses the 2D+T method for hull optimization of double-stepped planing hulls at the early-stage design. The method is applied to investigate the impact of various step configurations on the performance of stepped planing hulls in calm water and waves. The 2D+T method utilizes pressure distributions along the hull length to calculate forces in calm water and incorporates momentum variation theory to mathematically simulate rigid body motions in waves. Previous studies have validated the accuracy of this method. The paper conducts a parametric study on a double-stepped hull, analyzing the effects of different step configurations on hydrodynamic performance in calm and rough water conditions. The results suggest that optimal location of front step is somewhere near the mid-section, and that of rear step is in the vicinity of the center of gravity for steps with identical heights. It is demonstrated that this configuration minimizes the added resistance and wave-induced motions. It is concluded that the 2D+T method can effectively assist designers in hull optimization of stepped planing hulls in the early-stage design. Further research is recommended to consider the effects of step shape in the hull optimization.

The Lagrangian Differencing Dynamics (LDD) method, which simulates incompressible fluids with a free surface, has been extended to model planing of fast boats on calm water. It accurately handles rigid-body Fluid-Structure Interaction (FSI) through implicit solving of the Navier-Stokes equations and Lagrangian flow of water parcels, with walls represented as freely moving and deforming triangle meshes. The coupling involves direct exchange of fluid forces and wall motion. To validate the method, simulations of a hard-chine planing hull form were performed, comparing the results to experimental data. The resistance force and trim angles were analysed, for beam Froude coefficients Cv 1.4 and 2. The pressure distributions along the hull bottom and wave elevation around the hull were also examined. Due to its meshless Lagrangian nature, setting up a simulation only requires surface representation of the hull while utilizing modern GPUs allows obtaining results within minutes, making it suitable for optimization of planing hull forms.

The “design spiral” of a new ship consists of various milestones, one of them dealing with resistance prediction of the fully appended hull and with the proper placement of appendages, especially in the stern part of the ship where a complex 3D flow grows up. Applying an open-source code, the Open-Source Field Operation And Manipulation (OpenFOAM) one, in this paper it’ll be shown a fast numerical, robust and user-friendly procedure for the designers to achieve struts proper alignment rather than rely on a traditional more expensive, both in time and costs, Experimental Fluid Dynamics test campaign. An open-access data of a twin-screw propellers ship, the David Taylor Model Basin (DTMB) 5415, has been here considered to carry out the Fast Procedure. Once the test case has got through the Verification and Validation procedure, different kinds of simulations have been performed to assess that a Double Model simulation with the effects of trim, sinkage and propellers can describe with an adequate degree of accuracy the orientation of the field. It has been possible to carry out this last assessment through the generation of a cloud of points next to the struts position to obtain the orientation of the field and evaluate the difference between simulations. Two substantially hydro-dynamically equivalent approaches have been considered to design new struts in order to minimize their interactions with the hull and other appendages. Through the use of this Fast Procedure, the design time is evaluated equally to a few days, and it can be performed without specific knowledge or huge computational resources and so it can be considered industrially affordable.

Estimating shallow water resistance for a vessel is an issue of primary importance for inland water navigation, not only for determining the total power absorbed by the propulsors but also for predicting the far-field wave pattern necessary to assess the wake-washing effect on the shores. Once it is not possible performing model tests for a specific water depth or it is not possible to execute complex CFD simulations, it is necessary to estimate the shallow water effect and add it to the deepwater results. Traditional empirical methods usually refer to the subcritical regime for shallow water; however, for several applications, also critical and supercritical regimes require attention. The present work analyses the shallow water effect adopting a linearised theory for wave resistance prediction using the thin ship approximation and an empirical formulation for the viscous resistance. Such a methodology allows for determining a procedure for estimating shallow water effects for slender semi-displacement ships operating also in critical and supercritical regimes. The novel resulting process is tested on a reference semi-displacement hull designed for navigation in lagoons. The results are compared with conventional empirical methods and RANS calculations in shallow water, highlighting the agreement of the proposed method with the CFD calculations for the critical and supercritical regimes.

The assessment of the maneuverability of high-speed vessels is crucial during the early stages of their design. To predict the maneuvering characteristics of a vessel, the accurate assessment of hydrodynamic derivatives is necessary. Thus far, several experimental, analytical, and empirical methods have been utilized to determine such hydrodynamic coefficients. Nonetheless, nowadays, numerical methods are also viable alternatives because of their accuracy and efficient computational time. This paper introduces a hybrid numerical-theoretical method to compute the hydrodynamic coefficients. CFD simulations based on the Reynolds-Averaged Navier Stokes equations (RANS) are performed by Ansys-CFX software. The Static Drift Tests (SDTs) are conducted at deliberately chosen velocities and in various yaw angles, spanning from –20° to 20°. Mesh sensitivity analysis has been carried out and to validate the proposed numerical model, the results are compared with the available experimental data. Linear and nonlinear hydrodynamic derivatives of the planing craft are computed using a combined method. A comparison between the obtained hydrodynamic coefficients and those calculated using Lewandowski’s semi-empirical method for hard-chine planing hulls has been made. The findings indicate that the suggested hybrid model has the capability to predict the maneuverability performance of a marine vehicle at the preliminary design stage. The results comprise longitudinal force, sway force, and yawing moment in diverse drift angles. The contours of the wetted surface area over the bottom of the vessel and the wave pattern around the transom are presented and discussed.

Manoeuvring is one of the fundamental qualities of the ship. It has a direct impact on the operability of the unit and therefore on the shipowner’s perception of quality. Furthermore, the manoeuvrability forecasting models are extremely sensitive to the geometry of the hull and appendages and thus closely related with the type of the unit. In this article, an innovative methodology for predicting the manoeuvring characteristics during the conceptual design phase is presented. It may be applied to all types of vessels, especially those requiring a specific study of manoeuvrability, such as fast hulls. Here, a destroyer has been considered. Starting from 15 hulls geometries, a fleet of 225 ships has been generated, by changing systematically the ratio L/B, B/T and the block coefficient C_B. This way a 3-dimensional Central Composite Circumscribed (CCC) has been obtained, that comprehends a total of 15 experimental points for each base hull. Manoeuvring calculations has been performed on each vessel of the fleet and the main manoeuvring dimensionless quantities has been related to some simple variables, known during the conceptual phase. With a greedy approach, the adjusted coefficient of determination unmapped: inline-formula unmapped: math unmapped: mover unmapped: mrow unmapped: mi Runmapped: mo ‾² has been maximized. This way, from the collected data, the best possible linear models for manoeuvring characteristics are obtained. This is because no statistical significance filtering of the variables is performed, as instead happens in the classic stepwise approach.

The increasing complexity of vessels’ facilities and systems, the high economic impact of maintenance costs, and the need for high reliability and efficiency have led to a growing interest in condition-based maintenance (CBM). In this contest, machine learning (ML) has proven to be a powerful tool in approaching CBM tasks, as it can handle high-dimensional and multivariate data and extract hidden relationships within them in complex and dynamic environments. Here we propose a diagnostic model for monitoring the state of marine diesel engines and their components through the analysis of process parameters and ML tools. The model employs an artificial neural network (ANN) to estimate the optimal engine parameter value for normal condition operation. Deviations between measured real-time signals and optimal estimated values are used as indicators of potential faults, facilitating early detection and prevention. The calibration and performance evaluation of the diagnostic model are conducted on simulated fault data generated through GT-Power simulation tool. This approach to engine monitoring may overcome some limitations of ML algorithms based on supervised models, which rely on historical data containing information about anomalous activities or faults that are often not available.

Liquefied Natural Gas (LNG) has recently become a popular fuel in the shipping industry due to its low emissions and high energy density. However, it requires one or more bulky cryogenic tanks for storage onboard. Considering a traditional fast ferry, it is hard to find onboard a location for tanks, thus hindering the retrofit of existing ships. In this context, Compressed Natural Gas (CNG) might be a viable solution, since it can be more flexibly stored onboard and has greater availability in minor ports compared to LNG. Hence, this article investigates the feasibility of retrofitting the propulsion system of a fast ferry to employ CNG as fuel. After a review of the pros and cons of CNG and LNG as alternative fuels to marine diesel oil (MDO), a critical analysis of the technical requirements for retrofitting a fast ferry with CNG propulsion systems is carried out. Defined the layout and changes of the refitted unit, its performances are assessed on a test operative scenario. The study concludes that CNG retrofitting is technically feasible and provides several benefits, including lower emissions, higher levels of performance and higher reliability compared to LNG. Nevertheless, the retrofit requires significant changes to the ship layout and its fuel system to fit the required number of CNG cylinders.

The analysis of magnetic signature and the consequent identification of mitigation strategies are crucial issues in naval applications. The possibility to evaluate the magnetic signature of some essential components and structures during the design phase, represents an interesting opportunity to enhance ship design in terms of stealth capabilities. The current paper focuses on the assessment of the magnetic signature produced by a propulsor from a military ship with a fiberglass hull. The propulsor largest and heaviest components, which contribute most to the MS, were considered in the analysis. The numerical analysis carried out by means of a finite-element method technique was based on a simple theoretical model involving the concepts of averaged magnetization and of averaged permeability. The developed investigation is aimed at comparing the magnetic signature of a traditional propulsor with the one achievable by replacing the original ferromagnetic materials with weakly ferromagnetic ones and with a non-magnetic material, such as Aluminum, in the coating of the electric motor. The magnetic signature produced in the underwater region nearby the propulsor is consistently reduced and it is proved that the effect of Aluminum used in place of Cast iron is remarkable in determining this reduction. Therefore, the selection of suitable materials for the most critical parts in terms of magnetization and permeability, represents an effective yet simple strategy to improve the stealth properties of military ships. The possibility to use a simple model to evaluate the magnetic signature during the design phase is, therefore, essential to support a convenient selection of materials.

The paper presents a thermodynamic simulator of a marine four-stroke medium speed engine, fueled by methanol. The study stems from the current lack of information on methanol marine engines, whereas there is a growing interest in this type of alternative fuel, also in the maritime field. The numerical model, developed in Matlab^©-Simulink^© language and structured in a modular form, is derived from a natural gas marine engine simulator, developed by the authors and already described and validated in a previous research study. In the methanol engine model, for the in cylinder phenomena calculation, the zero dimensional actual cycle approach is adopted, while the turbocharger compressor and turbine are simulated by their performance maps. After a short description of the original natural gas simulator, the paper reports the variations introduced for adapting the engine model to the methanol fuel mode. The obtained outcomes are compared with data referring to a dual fuel natural gas engine, available in the literature. This comparison, between the simulated results of the two fuel modes of the engine, aims at highlighting the differences in efficiency and carbon dioxide emissions, in order to improve the environmental impact of the medium and high-speed vessels.

It is very common to use stern trim control devices in order to improve hydrodynamic performance of high speed vessels. Effect of stern trim control devices (wedges, trim tabas, interceptors) was analysed on the basis of dozens of tested projects of semi-displacement and planing hulls. Projects were tested in the large towing tank (276 m × 12.5 m × 6 m) which enabled that fairly large ship models were manufactured. Corresponding Reynolds numbers in model scale were larger than 1 × 10⁷ for the majority of conducted tests. Focus of the research was oriented towards higher speeds, i.e. especially limiting speeds where it is considered that impact is no longer positive. Resistance force and changes in dynamic trim angle were monitored and described. Influence of the characteristics of the hull (ratio of main dimensions, LCG position, deadrise) was observed and commented. On the basis of conducted analyses guidelines are created with the intention to serve as simple practical tool in early design phases for quantitative evaluation of possible gains.

Catamarans are popular in the offshore sector as they combine good transverse stability and ample deck space with low wave resistance. However, their slender hull shape results in low restoring qualities in heave and pitch motions. The large motions in rough weather can often result in water impacting the underside of the deck connecting the two hulls, a phenomenon called wet deck slamming. The impulse excitation from wet deck slamming can then produce a transient hydroelastic response of the structure called whipping. Whipping excites mode shapes that would not normally be present in the response, as their natural frequencies are significantly higher than the wave encounter frequency. This results in detrimental contributions to fatigue life through high-amplitude cyclical bending moments. Both the calculation of slamming loads and the prediction of resulting structural responses have been a challenge for several decades. The highly nonlinear and three-dimensional character of the phenomenon, combined with the strongly coupled fluid-structure interaction means that it is unpredictable, and even the definition of slamming events has been a matter of disagreement among researchers. Experiments are still a vital part of these investigations, for validating ever-improving numerical techniques. An essential issue with experiments is the extent to which mode shapes and natural frequencies can be emulated in model scale. Traditional hydroelastic models are segmented and use either a flexible backbone or flexible joints to introduce stiffness. This often results in an excellent description of the 2-node bending mode, but an increasing error for higher modes leads to stress inaccuracies. In this investigation, a continuous model of a catamaran is designed and produced for hydroelastic experiments. The advantages and limitations of the concept are identified, the verification against structural models is presented, and the calibration of the measurements is discussed.

Typically, performance evaluations of High Speed Craft (HSC) are done via towing tanks, however, these facilities come with a high cost, making them inaccessible to many researchers. An alternative testing technique is the free-running test. It provides significant flexibility by not imposing strict equipment requirements and can be carried out in any body of water, offering a more cost-efficient and practical approach to assessing the overall performance of an HSC. This paper presents the development of a free-running scaled model which involved constructing the hull, incorporating data acquisition systems (DAQ), and designing, integrating, and testing the propulsion and steering systems. In addition, this paper presents methods for monitoring the surrounding sea state using a stereo-vision system and commercial wave buoys.

The transition to zero-emission energy systems introduces new challenges in fast ferry design, particularly in relation to the increased weight and cost associated with stored and consumed energy. Hydrofoils may address these challenges by reducing the energy consumption and increasing the operational range.

This study compares the energy efficiency of hydrofoiling fast ferries to that of conventional slender catamarans across a range of vessel sizes and design speeds. To achieve this, a set of recently developed vessel designs and simulation models are employed to estimate vessel resistance. The Lift-to-Drag ratio (L/D ratio) is used for fair comparison and generalization.

The study finds that the L/D ratio of optimized hydrofoil vessels increases slightly with speed up to an optimum design speed, after which it drops due to the increased importance of strut resistance and wing loading constraints posed by cavitation. The optimum design speed varies with vessel size, from approximately 28 knots to approximately 33 knots for design masses from 26 tonnes to 141 tonnes, respectively. In contrast, the L/D ratio of conventional catamarans operating at service speed is approximately proportional to unmapped: inline-formula unmapped: math unmapped: msup unmapped: mrow unmapped: mi Uunmapped: mrow unmapped: mo −unmapped: mstyle unmapped: mfrac unmapped: mrow unmapped: mn 3unmapped: mrow unmapped: mn 2. A benefit of scale was identified for both vessel types.

Hydrofoil vessels offer greater advantages as the design speed increases or the vessel mass decreases. For vessels weighing 78 tonnes and 141 tonnes, the critical speeds for achieving net energy savings were determined to be approximately 25 knots and 27 knots, respectively. Opting for a hydrofoil design instead of a slender catamaran can result in energy savings of more than 54 % within the investigated speed and mass ranges.

Furthermore, the study presents a breakdown of the key resistance components of hydrofoil vessels, indicating that up to 54 % of the overall resistance originates from air resistance and struts-related resistance components within the investigated design parameter ranges.

Zero emission targets, as long-term global goals for climate protection, and the IMO GHG emission reduction strategy, fully involve ship design in a complex process of research and technological innovation. This paper proposes a feasibility study of a hydrogen fuel cell powered high-speed passenger craft. The passenger craft is intended to operate in the Amalfi coast, carrying 220 passengers at a route speed of 20 kn. The dimensions of the passenger craft are 30 m Length, 10 m wide. The feasibility study of the implementation of a PEM fuel cell propulsion system, has been structured ensuring the mutual consistency between all the subsystems: propulsion plant, energy storing and payload. Moreover, critical aspects related to safety has been analyzed according to the updated regulations.

The completely shipping sector is engaged toward the reduction of greenhouse gas emission. Both IMO and the EU already set their pathways along the GHG strategy aiming to reach a shipping sector fully carbon neutral. The two regulatory bodies issued a first set of requirements with further ones under preparation. High-Speed units will be indeed also involved by these efforts in a very specific way, considering their very peculiar operation profiles. In order to improve the carbon footprint for a high-speed craft, a reference unit (e.g. 50 mt in length) is considered, engaging innovative technologies and new fuels. Being the port infrastructures also part of the sustainable mobility, the interaction between the ship and the harbor facilities are also considered. Ships at berth generate their electricity depending on their own auxiliary engines, emitting air pollutants and creating noise. This makes ports a major and growing source of pollution. Therefore, using fuel cell, main aims of this paper are the shore-side power concept economic analysis and the shore-side power and environmental effect.

In the building of polymer-based composite high-speed marine vehicles, the designer has many more options than when building with equivalents of this material. The designer is faced with the possibilities of choosing a wide variety of fiber and resin materials, with the options for combining these materials almost endless. This width of the borders generally worries high speed marine vehicle designers, and with this concern, the designer tends to build heavy vehicles by using more materials than necessary to stay in a very safe zone. A heavy vehicle unfortunately does not serve sustainability, which is the main driver of designs today. In this study, the weight of the high-speed marine vehicle produced with such a design concern is improved by (1) optimizing the sequences of certain materials that the builders have established a strong supply chain, and (2) using today’s advanced composite material components, which the manufacturer has not used before. CFD methods and some rule-based approaches were used to calculate the pressures and accelerations around the hull. As a result of the analyses performed with the help of laminar theory and Tsai-Wu failure criteria, it has been seen that approximately 25% of the hull weight in the first way and almost 15% in the second way can be lightened. In light of the results obtained, suggestions will be made to marine vehicle designers for more sustainable building.