KISS (Keep It Sustainable and Smart): A Research and Development Program for a Zero-Emission Small Crafts

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 frame are also highlighted

Vulnerability assessment of surf-riding-broaching and pure loss of stability for Systematic Series D1 model

This paper is focused on the first and second level vulnerability assessment of Surf riding/Broaching and Pure Loss of Stability Criteria according to IMO second generation intact stability criteria. The calculations are performed for the semi-displacement twin-screw round-bilge hull form model D1 of the Systematic Series D. This model has hull form and service speed representative of corvettes built in 90-ties. The considered loading condition is obtained from Italian Navy ships statistics. Both criteria are analysed for different operational characteristics to evaluate the speed limits where the ship is not vulnerable. Model D1 is found to be vulnerable to both failure modes at service speed. Performing 2nd level of both criteria 'safe' speed is around 19 knots for surf-riding and around 15, 5 knots for pure loss. The obtained results are commented and compared against similar ships from the relevant state of the art papers

The Impact of Different Bow Shapes on Large Yacht Comfort

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 among the design solutions on a reference large yacht favours the option nested with a bulb, contradicting the expectations in favour of a vertical bow concept. The discussion and conclusions provide a way forward for additional analyses and investigations aimed at proposing suitable multicriterial design guidelines for large yachts. However, the results also show the unsuitability of AWI environmental and encounter conditions for hull form ranking

Application of the second generation intact stability criteria for fast semi displacement ships

The Second Generation Intact Stability Criteria (SGISC) are developing since 2002 after a series of naval accidents, which clearly demonstrated that actual stability criteria are not adequate to account for significant changes in the design and operation characteristics of new commercial ships. The philosophy is a multi-level approach in which successive levels are less conservative and more accurate, arriving, if necessary, to the Direct Assessment of stability failures. In this paper, Level 1 and 2 of the three main stability failure modes of the SGISC: The Parametric Roll, Pure Loss of Stability and Surf-riding/Broaching are studied on four naval ships the Systematic Series D twoparent hulls, the ONRT, benchmark ship from research version of the US Navy, and FREMM, a class of multi-purpose French-Italian frigates. For every ship typology, when one was found vulnerable to 2nd level, the corresponding criteria were analyzed by navigation conditions to estimate operational limits

Application of the 2nd Generation Intact Stability Criteria for fast semi displacement ships

The Second Generation Intact Stability Criteria (SGISC) are developing since 2002 after a series of naval ac-cidents, which clearly demonstrated that actual stability criteria are not adequate to account for significant changes in the design and operation characteristics of new commercial ships. The philosophy is a multi-level approach in which successive levels are less conservative and more accurate, arriving, if necessary, to the Di-rect Assessment of stability failures. In this paper, Level 1 and 2 of the three main stability failure modes of the SGISC: The Parametric Roll, Pure Loss of Stability and Surf-riding/Broaching are studied on four naval ships the Systematic Series D two-parent hulls, the ONRT, benchmark ship from research version of the US Navy, and FREMM, a class of mul-ti-purpose French- Italian frigates. For every ship typology, when one was found vulnerable to 2nd level, the corresponding criteria were analyzed by navigation conditions to estimate operational limits

Surf-Riding-Broaching and Pure Loss of Stability vulnerability on Systematic Series D1 Model

The development of the IMO second generation intact stability criteria is based on a multi-level approach. In each level the accuracy of the analysis is increased and if a possible vulnerability is detected the next level is applied. A ship, depending on its characteristics and external conditions, may be considered vulnerable to one or more stability failure modes. For each of the stability failure modes, the study will begin applying the first level of vulnerability, and in case the ship is considered vulnerable, to one or more failure modes, the second level of vulnerability will be applied to specific mode. This paper is focused on the first and second level vulnerability assessment of the Surf riding/Broaching and Pure Loss of Stability. After testing the procedure on IMO benchmark ships, these two criteria are verified on the semidisplacement twin-screw round-bilge hull forms of the Systematic Series D, by Kracht and Jacobsen (1992), model D1. This model is representative hull form and service speed of Italian Navy ships and the considered loading condition is taken from the naval ship statistics. These two criteria are analysed for different operational characteristics to evaluate the speed limit

Surf-riding failure mode: from IMO criterion to Direct Assessment procedure and application on Systematic Series D

The paper follows contemporary development of the second generation IMO intact stability criteria and describes application of vulnerability criteria for surf-riding / broaching to Systematic Series D parent hull. Model D1 is a semi-displacement twin-screw round-bilge hull by Kracht and Jacobsen (1992) representative of several naval ships built during 90ties. The modern hull form and the complete set of resistance and selfpropulsion results available for the Systematic Series D models offer a possible benchmark case to support scientific community for further criteria verification. More in particular, the Direct Assessment of surf-riding failure mode has been addressed by two approaches. The first one is based on the 1 DoF nonlinear differential equation for surge motion solved analytically and the occurrence of homoclinic bifurcation is examined. The second approach is based on a 6DoF ship dynamics simulation taking into account wave, propeller and maneuvering forces and moments. Instantaneous wetted surface is considered for restoring and Froude-Krylov forces while ship resistance, thrust and maneuvering are based on the calm water performances. Calculations are performed for four ship speeds at the wave with /L = 1 for different wave steepness. A condition where the occurrence of the surf-riding by 1DoF has been verified, is further analyzed by 6DoF, exploring the effect of the nonlinearity in the Froude Krylov force. The limit wave steepness is found for each considered ship speed

Case studies of SGISC Operational Limitations for pure loss of stability and excessive acceleration

The present paper reports an application of Operational Limitations related to route and to maximum significant wave height, on two case studies, a Ro-Ro cargo and a bulk carrier. The ships have been found vulnerable to Level 2 for pure loss of stability and excessive acceleration, respectively. Two different possible routes have been selected for Operational Limitations, considering the scatter diagrams related to the areas crossed by the ship during the voyage. When the ships have been found not able to operate along one route, the maximum significant wave height has been identified

CFD simulations for surf-riding occurrence assessment

Surf-riding phenomenon occurs when a ship sailing in following waves is accelerated to wave celerity. In this paper, surf-riding occurrence is studied for the parent hull of the Systematic Series D by 3 degrees of freedom (DOF) CFD simulations. Simulation cases are chosen following IMO recommendations for a wavelength to ship length range and following IMO criterion for ship speed cases. Initial conditions for simulations are obtained from 1-DOF surge motion equation solved by bifurcation analysis. The aim is to define surf-riding limits for ship operability with a less conservative approach, taking into account force changes in waves compared to the one used in the 1-DOF model, which considers calm water approximations. After defining surf-riding boundaries in terms of wave heights for different wavelengths and ship speeds, calculated forces are analysed to evaluate the magnitude and trend of non-linear effects due to wave elevation and ship-wave interaction. A detailed analysis is conducted on resistance, thrust, and wave forces in surging and surf-riding conditions, comparing the applied methodologies. The introduction of wave velocity field influence in the thrust force and the calculation of Froude-Krylov wave-force up to actual wave profile have been discussed and identified as possible improvements of 1-DOF approach