This paper presents an experimental research for the assessment of pressure field on the bottom of a mono-hedral hard chine hull at high relative speed. Tests have been performed in rough sea for two wave lengths at Fn ranging from 0.79... more
This paper presents an experimental research for the assessment of pressure field on the bottom of a mono-hedral hard chine hull at high relative speed. Tests have been performed in rough sea for two wave lengths at Fn ranging from 0.79 to 1.46. The measured pressures have been analysed in time and in frequency domain. The pressure distribution along a rectangular panel of the hull bottom has been identified. The comparison of measured values and those ones provided by Classification Societies has been performed and pressure results have been used to investigate the interactions between the fluid and the craft structure. The elastic behaviour of different bottom panels is analysed, and the scantling of a typical bottom panel, made from four materials, have been calculated, in order to investigate the structural dynamic behaviour.
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The results of experimental tests relative to resistance, seakeeping and roll decay of a warped hard chine hull form, suitable for large yacht design are reported. To better investigate the effect of hard chine, a round bilge identical... more
The results of experimental tests relative to resistance, seakeeping and roll decay of a warped hard chine hull form, suitable for large yacht design are reported. To better investigate the effect of hard chine, a round bilge identical model has been tested. Resistance tests have been performed at FV ranging from 0.90 to 4.14, for three different LCG. Results for resistance, sinkage and trim are given. For the most realistic condition dynamic wetted surface is determined separating pressure and whisker spray areas to allow reliable full scale powering predictions. For the same static trim condition, heave, pitch and accelerations have been measured for head sea at FV = 1.35 and 1.89 in regular waves for different /Lratios at constant wave steepness H/ = 1/50. Roll decay at five speeds and roll at zero speed were investigated. The reported data and considerations represent a reference for the implementation of hard chine hull form in the design of displacement and semidisplacement large yachts.
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Research Interests: Engineering, Civil Engineering, Geography, Geology, Computer Science, and 15 moreBiomedical Engineering, Computer Simulation, CFD Analysis, Cancellous bone, Intervertebral disc, Diffraction, CFD and numerical grid generation, Indentation, Debris, Correctness, Interdisciplinary Engineering, Boiling, Agglomerate, fds, and Fire Test
Resistance tests in calm water conditions provide performance predictions of ships in an ideal and unrealic sea state, which can be found only in sea trials under particular condition. Focus has to be made on effects of various... more
Resistance tests in calm water conditions provide performance predictions of ships in an ideal and unrealic sea state, which can be found only in sea trials under particular condition. Focus has to be made on effects of various environment conditions, in particular rough sea. Evaluation of added resistance in waves and determination of additional power to install above the calm water power requirements are assuming an increasing importance in displacement ship's design and a growing interest is focused on them. The purpose of this paper is to present towing tank methodologies and procedures for assessment of ship's behavior in regular sea with particular attention on added resistance. The aim is to allow towing tank to test ships in regular seaway and then to evaluate motions and resistance in rough sea. ITTC guidelines and procedures are considered in hull outfitting and in setup of the wave-making system. A tanker hull model is considered in experiments and preliminary calm water resistance and self-propulsion tests are carried out before the tests in regular waves. An experimental program in regular sea state is presented, developed under ITTC guidelines and procedures. Discussion on the towing tank instruments, towing experiments and error propagation due to the different experimental set up is given.
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Surf-riding/broaching failure mode is one of the Second Generation Intact Stability Criteria (SGISC) dealt by IMO. The SGISC are structured with a multi-tiered approach: Level 1, Level 2 and Direct Stability Assessment (DSA). When a ship... more
Surf-riding/broaching failure mode is one of the Second Generation Intact Stability Criteria (SGISC) dealt by IMO. The SGISC are structured with a multi-tiered approach: Level 1, Level 2 and Direct Stability Assessment (DSA). When a ship does not verify one level, the next once must be applied, or the ship design must be modified. If ship changes are not feasible, Operational Measures (OM) can be provided to avoid dangerous situations and reduce the likelihood of stability failures. The OM are divided into Operational Limitations (OL) related to areas or routes and related to maximum significant wave heights and Operational Guidance (OG). The surf-riding criterion has been applied on the parent hull of the Systematic Series D, a fast semi-displacement naval hull with forms typically vulnerable to surf-riding phenomenon. The 90 m length ship results vulnerable to Level 1 and 2, therefore Operational Measures have been discussed and provided for a hypothetical route in the Mediterranean Sea (Area 26). Following the OL, in considered Area 26 the ship operations are limited when significant wave heights exceed 3.8 m. The simplified OG define critical ship speeds to be avoided for each considered sea state.
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Publisher Summary This chapter considers a trimaran ship equivalent to a typical high speed craft in service in the bay of Naples and carries out resistance model tests. Two vessels having different outrigger hull forms were designed on... more
Publisher Summary This chapter considers a trimaran ship equivalent to a typical high speed craft in service in the bay of Naples and carries out resistance model tests. Two vessels having different outrigger hull forms were designed on the basis of required lay-out of the limits in the main dimensions and of the available data from existing design. The investigation was carried out on a large model to verify the influence of the main hull trim and of the outrigger hull form and position on the trimaran hydrodynamic resistance. The investigation was carried out on two geosim models of a trimaran hull configuration with the goal to compare the ITTC'57 with the ITTC'78 model–ship correlations. For this last purpose a form factor of the trimaran was determined by different methods. The results show that the ITTC'57 could be preferable to ITTC'78 model–ship correlation in the higher Froude number range. At the designed high Froude numbers of the considered trimaran, the Wigley side hull form does not seem realistic. However, because of a lower total resistance, this side hull form could be adopted at lower Froude numbers.
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<jats:p>The International Maritime Organization (IMO) finalized the Second Generation Intact Stability Criteria (SGISC), in February 2020. They are intended to be included in Part A of the 2008 International Code on Intact Stability... more
<jats:p>The International Maritime Organization (IMO) finalized the Second Generation Intact Stability Criteria (SGISC), in February 2020. They are intended to be included in Part A of the 2008 International Code on Intact Stability in the following years. The SGISC consider five modes of dynamic stability failure in waves: parametric roll, pure loss of stability, surf-riding/broaching to, dead ship condition and excessive acceleration. In this paper, two semi-displacement, round bilge and transom stern hull forms, the parent hull of the Systematic Series D and the ONR Tumblehome, i.e. typical naval hull forms, are examined. Although naval ships are not directly impacted by SGISC, they are sensitive to dynamic stability failure phenomena due to their geometry and range of service speeds. The procedures to assess the ship vulnerability to the dead ship condition and excessive acceleration criteria, referring to the latest drafts of the criteria (SDC 7/5, 2019), were implemented in Matlab®,. The limiting KG curves associated with this set of criteria were obtained for each vessel. The minimum allowable KG curve associated with the excessive acceleration criterion was compared with the maximum allowable KG curve associated with dead ship condition, to investigate the existence of a safe operational area.</jats:p>
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The importance of comfort during transfer and stationing becomes a key performance parameter for large yacht design, on the same level as propulsive issues. Such a matter extends questions in terms of form and service demand to the motion... more
The importance of comfort during transfer and stationing becomes a key performance parameter for large yacht design, on the same level as propulsive issues. Such a matter extends questions in terms of form and service demand to the motion behaviour of the unit in waves. Relevant studies refer to outdated hull forms not specific to modern large yachts. In this study, five hull forms with different bow concepts represent the most common design solutions for yachts at constant draught and displacement. The preliminary ranking on the effect of alternative bows on comfort requires the definition of internationally accepted comfort standards. Here, the AWI 22834 guidelines for large yachts provide the service and environmental conditions and criteria for the comfort analysis, being the only reference specific to yachts. The calculations employ a strip-theory-based numerical model to provide results of easy understanding for designers during the early design stage. The obtained ranking amo...
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<jats:p>Surf-riding/broaching failure mode is one of the Second Generation Intact Stability Criteria (SGISC) dealt by IMO. The SGISC are structured with a multi-tiered approach: Level 1, Level 2 and Direct Stability Assessment... more
<jats:p>Surf-riding/broaching failure mode is one of the Second Generation Intact Stability Criteria (SGISC) dealt by IMO. The SGISC are structured with a multi-tiered approach: Level 1, Level 2 and Direct Stability Assessment (DSA). When a ship does not verify one level, the next once must be applied, or the ship design must be modified. If ship changes are not feasible, Operational Measures (OM) can be provided to avoid dangerous situations and reduce the likelihood of stability failures. The OM are divided into Operational Limitations (OL) related to areas or routes and related to maximum significant wave heights and Operational Guidance (OG). The surf-riding criterion has been applied on the parent hull of the Systematic Series D, a fast semi-displacement naval hull with forms typically vulnerable to surf-riding phenomenon. The 90 m length ship results vulnerable to Level 1 and 2, therefore Operational Measures have been discussed and provided for a hypothetical route in the Mediterranean Sea (Area 26). Following the OL, in considered Area 26 the ship operations are limited when significant wave heights exceed 3.8 m. The simplified OG define critical ship speeds to be avoided for each considered sea state.</jats:p>
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This contribution looks at experimental ship motion and load measurements in head and beam seas
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For fast slender hullforms, the damping forces due to the generated waves are so small that the damping forces relative to viscosity cannot be neglected in evaluating the vertical motions. In this paper the numerical and experimental... more
For fast slender hullforms, the damping forces due to the generated waves are so small that the damping forces relative to viscosity cannot be neglected in evaluating the vertical motions. In this paper the numerical and experimental assessment of the vertical motions in head sea for three mono-hulls are presented. The considered hulls are fast slender displacement type with transom stern and L/B ratios 14, 12, 8. The most slender hull is a trimaran main hull, the second one is a catamaran demihull and the last one is the Model 5 (Blok and Beukelman, 1984). The calculations were performed using 2 \ubd D high speed theory by Faltinsen and Zhao (1991). To obtain potential flow theory results the viscosity correction from the cross flow was added. The effect of the viscosity from cross flow was considered as reported by Lee (1977), Chan (1992), Centeno (2000). At the Trieste towing tank experimental program was conducted for the catamaran demihull and the trimaran main hull for four different speeds while for the Model 5 experimental data were collected from the literature. The effect of cross flow coefficients is evaluated and discussed, and empirical coefficients are set. Furthermore, the influence of slenderness ratio and speed is discussed and finally some conclusions are given
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This paper presents the results obtained by MArine HYdrodynamics Research Group of Department of Industrial Engineering (DII) at University of Naples regarding design and development of a zero emission craft for service in Mediterranean... more
This paper presents the results obtained by MArine HYdrodynamics Research Group of Department of Industrial Engineering (DII) at University of Naples regarding design and development of a zero emission craft for service in Mediterranean coastal Marine Protected Areas (MPA).
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This paper reviews a state-of-the-art zero emission propulsion system for a battery-powered small craft. The main aspects considered are the available propulsion systems, energy storage, and dock battery charging. This underlying activity... more
This paper reviews a state-of-the-art zero emission propulsion system for a battery-powered small craft. The main aspects considered are the available propulsion systems, energy storage, and dock battery charging. This underlying activity is part of the KISS project, a research and development program in the frame of the EU-funded “Piano Operativo Regionale CALABRIA FESR-FSE 2014–2020 ASSE I–PROMOZIONEDELLA RICERCA E DELL’INNOVAZIONE”, which is aimed at designing and building a physical prototype. Its hull form is based on previous research conducted by the authors, and the powering performances were preliminarily predicted by CFD simulation. The KISS project represents a successful example of an electric small craft with performances and a mission profile comparable to competitors with conventional propulsion. Such a target has been achieved by a concurrent design that considers the hull form, engine, propulsion system, and energy storage onboard. Safety issues and the regulatory f...
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An experimental campaign test has performed on the 1:20 scaled moored model of ISWEC (Inertial Sea Wave Energy Converter). The annual productivity of the device is strictly correlated to the hydrodynamic properties of the floater.... more
An experimental campaign test has performed on the 1:20 scaled moored model of ISWEC (Inertial Sea Wave Energy Converter). The annual productivity of the device is strictly correlated to the hydrodynamic properties of the floater. Therefore, is fundamental to carry out an experimental investigation of the hydrodynamic performance of the floater and compare the results with the numerical codes. In this paper the experimental campaign is described. Two different mooring configurations were tested to understand the different influence of mooring forces on the floater dynamics. The non-dimensional Response Amplitude Operator (RAO) is representative of the hydrodynamic performances of the floater. Therefore, the device with both the mooring configurations has been tested in regular waves of constant wave steepness 1/50. Conclusions are commenting the differences a between numerical and experimental results and the impact of nonlinearities on hydrodynamic performances.
This chapter presents an assessment of the roll damping of DTMB 5415 naval ship model in both intact and 2 compartments symmetric damaged scenarios. A numerical assessment of roll decay is performed by CDAdapco StarCCM+ software... more
This chapter presents an assessment of the roll damping of DTMB 5415 naval ship model in both intact and 2 compartments symmetric damaged scenarios. A numerical assessment of roll decay is performed by CDAdapco StarCCM+ software investigating the accuracy and efficiency of the numerical approach. The sensitivity analysis on mesh refinement is performed for damaged ship while time step and turbulence models sensitivity is investigated for the intact ship. Numerical results for decay curves, natural frequency and period of roll for intact and damaged ship are plotted against experiments, performed at the University of Strathclyde, Glasgow, to verify the precision of the numerical simulations. Obtained numerical results are shown to be reasonably accurate although the calculation time still precludes the use of Computational Fluid Dynamics (CFD) analysis as a standard design procedure.
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This paper considers the assessment of vertical accelerations of high speed planing craft in waves as the principal element for the risk management approach, i.e. formulation and application of ope ...
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The rules and regulations inherent to the design pressures and scantlings of high-speed powercrafts are numerous, and regularly reviewed. Recently, the new ISO 12215-5:2019 made notable changes to the way high-speed crafts are analysed,... more
The rules and regulations inherent to the design pressures and scantlings of high-speed powercrafts are numerous, and regularly reviewed. Recently, the new ISO 12215-5:2019 made notable changes to the way high-speed crafts are analysed, including extending the acceleration experienced up to 8 g in certain circumstances. Nevertheless, despite the multiple iterations and variety of regulatory bodies, the seminal work undertaken on planing crafts throughout the 1960s and 1970s remains the foundation of any rule-based design requirement. Consequently, this paper investigates an array of recently published rules though a comparative design case study, the current state-of-the-art across a number of regulations, and the ultimate impact on scantlings. The study reveals that, despite divergence in intermediate calculations and assumptions, similar requirements are ultimately achieved. Eventually, discussion on the comparison undertaken and future trends in high-speed marine vehicles is prov...
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Multi-attribute design model of the patrol, search and rescue and/or antiterrorist craft (PASARAT) is developed. The aim of the multi-attribute design procedure is to find parameters and attributes of the feasible and Pareto-optimal... more
Multi-attribute design model of the patrol, search and rescue and/or antiterrorist craft (PASARAT) is developed. The aim of the multi-attribute design procedure is to find parameters and attributes of the feasible and Pareto-optimal vessels subject to constraints. The attributes considered are speed, allowable service time in prevailing sea conditions, acquisition cost of the vessel etc. Parameters of the model are: principal dimensions, coefficients and displacement of the vessel. Optimal propulsion engines are selected from the input engine catalogue, while fixed pitch propellers, surface piercing propellers and water jets are described via parametric regression models. Pareto-optimal designs found by applying the principle of non-dominance to the normalized attributes are sorted according to the Chebyshev metric. Multiple graphical presentations of the multi-dimensional design space are provided in order to gain much better insight into the performances of optimal vessels than it...
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This paper presents the results of a research program carried out on different trimaran hull forms and configurations suitable for medium size fast ferries. Resistance tests on large size scale models of the two different hull forms of... more
This paper presents the results of a research program carried out on different trimaran hull forms and configurations suitable for medium size fast ferries. Resistance tests on large size scale models of the two different hull forms of main hull and outriggers, both isolated and combined in different configurations have been carried out at the towing tank of Naples University. For each isolated hull and trimaran configuration the total resistance and running trim have been assessed. Wave pattern analysis was also performed by experimental tests and by numerical computations, so that the influence of each resistance component has been highlighted. The results of this work could be used as a reference in trimaran hull design and optimization.
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The good seakeeping characteristics of SWATH hull form are very interesting for small working craft and pleasure boats. Intrinsic limitations as the low values of weight per inch of immersion and transversal and longitudinal instability,... more
The good seakeeping characteristics of SWATH hull form are very interesting for small working craft and pleasure boats. Intrinsic limitations as the low values of weight per inch of immersion and transversal and longitudinal instability, can be acceptable and successfully managed when the mission profile does not ask for significant load variation and shift. The exploitation of SWATH concept is limited by the craft size, but if main dimensions allow enough static stability, this configuration appears very promising. SWATH behaviour in rough sea at zero and low speed have led to consider this hull form within the small craft design research program in progress at University of Naples Federico II.
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UDC 629.5.017/018.71 Summary The paper presents the results of planing hull seakeeping tests in irregular seas. The tested model belongs to a small systematic series developed at the University of Naples; it is a prismatic hull very... more
UDC 629.5.017/018.71 Summary The paper presents the results of planing hull seakeeping tests in irregular seas. The tested model belongs to a small systematic series developed at the University of Naples; it is a prismatic hull very similar to the well-known Fridsma’s models. The 16.7 degrees deadrise angle, length-to-breadth and load coefficient are representative of modern hull forms of pleasure boats. Tests in irregular waves have been performed at three speeds for one displacement in three sea states. The measured heave, pitch, acceleration at the centre of gravity and at bow have been analysed in the time domain and the results are presented in terms of significant values (the mean of 1/3 rd highest values). They are given in tabular and graphical form. Furthermore, the obtained results are commented with respect to the state of the art in planing hull seakeeping, and compared with the available experimental data from literature. The conclusions highlight the applicability of t...