High-speed Craft Research Articles

Vessel Motions and Work Interruptions Aboard a Fast Rescue Craft

A set of field trials were carried out aboard a Canadian Coast Guard fast rescue Rigid Hull Inflatable Boat. The vessel was outfitted with a data acquisition system to collect vessel and engine performance data and trialled in three wave conditions (approx. Beaufort 2 to 7). This paper focusses on the methodologies and results for calculating and investigating Motion-Induced Interruptions (MIIs). MIIs due to lateral and longitudinal overbalancing and sliding were investigated using the counting of motion events which are expected to cause an interruption, supported by a statistical analysis and examination of the distribution of the MII data. We conclude that MII assessments of small, light, high-speed craft such as the one studied should include longitudinal acceleration and pitch angle, typically assumed to be non-influential in MII assessments. Statistical treatments have promise for analysis of field-acquired MII data.

Kinematic and inertial hydroelastic effects caused by vertical slamming of a flexible V-shaped wedge

Due to the increasing use of composite materials in high-speed planing craft prone to frequent slamming, the interaction between the structural response and hydrodynamic loading, hydroelasticity, must be considered. In this work, a V-shaped wedge model with 20° deadrise angle was vertically dropped into the calm water to simulate a typical hydroelastic slamming. With varied impact velocity and flexural rigidity of the wedge bottom plate a wide range of hydroelasticity factors, 0.1≤R≤6.4, were examined. Measurements included rigid-body kinematic motions of the wedge model, spray root propagation, hydrodynamic loading, and structural response. It was found that the maximum deflection and strain occur in the chine-unwetted phase in this study. The kinematic effect of hydroelasticity changes the spray root propagation and hence the pressure, while the inertial effect increases the natural period of the plate.

Three-dimensional simulation and evaluation of the hydrodynamic effects of stern wedges on the performance and stability of high-speed planing monohull craft

This study analyzed the hydrodynamics of a high-speed monohull craft model through increasing its longitudinal stability to improve its performance. First, a high-speed planing monohull craft was simulated using computational fluid dynamics. The free surface was analyzed using a three-dimensional volume of a fluid model. The modeled craft with two degrees of freedom was solved using the overset technique for dynamic mesh. For verification, the results of this study were compared with those of an experimental test performed in the laboratory. Accordingly, it was found that the experimental and numerical results were in good agreement. The modeled craft also showed longitudinal instability at a speed of 8 m/s (equal to the speed of sailing). To eliminate this longitudinal instability and subsequently improve the longitudinal performance, craft stern wedges with triangular sections were added in three modes to examine their effects on the resistance and stability of the craft using computational fluid dynamics. Moreover, the results showed that due to the reduction of trim to about 42%, the longitudinal instability was removed at a constant speed, and as a result the longitudinal performance of the craft increased while the total resistance decreased.

Model scale prediction of seakeeping and global bending moment on a high speed craft

Estimating the forces acting on a high speed craft for structural assessment purposes is challenging due to the complex combination of hydrodynamic loads. These include wave pressures, slamming pressures and their load effects at a global ‘hull girder’ level. An experimental approach to validate the use of established strip theory methods for predicting the hydrodynamic wave pressure loads is presented here. A series of regular wave seakeeping tests on a small scale segmented hull model of a high speed craft were completed and compared to equivalent seakeeping calculations. Experiments were conducted with a 1:13.5 scale hull model of a 17-metre all weather lifeboat, which is typical of a high speed watercraft capable of operating in severe weather at exposed locations. The model is segmented into four sections, rigidly held together by an instrumented backbone beam which can measure shear force and bending moments at the segmentation points. The model was tested over a full range of operating speeds and wave encounter frequencies. Results are compared with two strip theory calculations, the first using a zero speed Green function and the second using a Rankine source method with a forward speed correction term. It is shown that the Green function strip theory provides better correlation at lower speeds (up to a Froude number of 0.4) and the Rankine source method is more appropriate at higher speeds. The experiments generally show good equivalence to calculations and demonstrate that strip theory gives reasonable predictions of the global bending moment assuming linearity with the wave height. Equivalently, this suggests that strip theory is an appropriate method to predict the hydrodynamic wave induced load component in displacement and semi-planing regimes. This unlocks the potential for strip theory to be used as part of a complete assessment of the seakeeping loads on a high speed craft by combining the wave induced loads with the other significant load components, which include the local hydrodynamic wave pressures and the transient loads caused by slamming impacts. This may be applied as part of an analysis to determine a craft’s safe operating envelope or for interpreting component loads within full scale trial data.

Study of the Interceptors Effect on Ship Manoeuvrability Using the Open Free Running Test Method

Interceptors are plates that are attached to the stern of the ship to produce lift that controls the trim angle of the ship. This paper describes the use of interceptors on the fast boat to enhance its ability to perform the turning manoeuvre. The ship model of High-speed crafts (HSCs) with a scale of 1: 26.9 is tested in an open pool with the open free running test method, namely the movement of the model is controlled from the edge of the pool with a remote control. The ship trajectory data is obtained by using the colour object tracking method, that is, the ship trajectory captured by the camera is processed based on colour filters. The main concern is the varying dimensions of the interceptor including 0% (no interceptor), 50% (half length), and 100% (full length) of the design cord length. The initial trim conditions are examined, such as even keel, trim by bow, and trim by stern with a trim angle of 2 degree. The test results show that the interceptor contributed to improve the manoeuvrability of the boat by decreasing the tactical diameter length respectively at half and full length of the cord by 8.8% and 17.9% in even keel, 6.3% and 15% in bow trim, and 12.9% and 14.8% in stern trim.

Naval Architectural Aspects in The Design of a Hybrid Hydrofoil-Submarine Craft

Indonesia is the largest archipelago country in the world. Territorial disputes and illegal fishing are some main threat of maritime defense. One of the solutions is to provide a multi-mission vehicle. Submarine craft has the advantage of undetectable to ambush the threats. Hydrofoil craft has the advantage of higher speed than the conventional high-speed craft. The purpose of this research is to combine two distinctive and one conventional concept into one craft. This craft has to has a light structure to support hydrofoil mode and able to submerge. The material of the hull uses aluminum and for wing and propulsion system structure use carbon steel. This craft uses hydraulic propulsion that the main engine moves the hydraulic pump. The hydraulic pump flows oil to the hydraulic motor where located in the nacelle. The hydraulic motor rotates the shaft and propeller. This propulsion system requires the propeller to submerge in the water, therefore the strut which supports the wing and propulsion system has to design retractable. All important parameters are included in this paper.

Effect of Angle of Attack Variation of Stern Foil on High-Speed Craft on Various Speed with Computational Fluid Dynamics Method

Effect of Angle of Attack Variation of Stern Foil on High-Speed Craft on Various Speed with Computational Fluid Dynamics Method

Utilization of Open-Source OpenFOAM Code to Examine the Hydrodynamic Characteristics of a Linear Jet Propulsion System with or without Stator in Bollard Pull Condition

With the development of high-speed crafts, new propulsion systems are introduced into the marine industry. One of the new propulsion systems is linear jet which is similar to pump jet and has a rotor, a stator, and a duct. The main difference between this system and pump jet is the placement of linear jet system under the hull body and inside a tunnel. Since this system, like a water jet, is inside the tunnel, the design idea of this system is a combination of a water jet and pump jet. In this paper, hydrodynamic performance of linear jet propulsion system is numerically investigated. To this end, the OpenFOAM software is utilized and RANS steady equations are solved using a k - ε turbulent model. The linear jet geometry is produced by assembling a Kaplan rotor, stator with a NACA 5505 cross section, and a decelerating duct. The results of numerical solution in the form of thrust, torque coefficient, and efficiency are compared with available experimental data for a ducted propeller, and good agreement is displayed. Subsequently, the hydrodynamic parameters are computed in two conditions: with a stator and without a stator. By comparing the results, it is observed that the total thrust coefficient of the propulsion system with a stator at all advance ratios increases by at least 40%. It is further observed that addition of a stator also improves its efficiency.

A Real Time Speed Modulation System to Improve Operational Ability of Autonomous Planing Craft in a Seaway

This study focuses on developing a control system to enhance the seaworthiness of Autonomous high-speed Planing Crafts (APCs). APCs operating at high-speed in a seaway encounter very high vertical accelerations which pose a hazard to payload and crafts' structural integrity. Therefore, for safety operation of APCs in a seaway it is proposed to employ a system termed vision-aided speed modulation system (VSMS). The proposed VSMS employs an embedded analytical tool termed Motion Assessment of Planing Craft in a Seaway (MAPCS) for the prediction of vertical accelerations and angular velocities, the APC might encounter in the incoming waves. As a response to the MAPCS predicted values the VSMS speed setting module modulates the craft's forward speed. All modules of the VSMS are presented together with their validation and system's preliminary operational results. It is concluded that VSMS might be an essential tool to considerably enhance the operational ability of APCs.

Implementation of Life Estimation Algorithm of Composite High Speed Craft Shell due to Cyclic Sea Pressure

Implementation of Life Estimation Algorithm of Composite High Speed Craft Shell due to Cyclic Sea Pressure

Industry 4.0: smart test bench for shipbuilding industry

Industry 4.0 promises to increase the efficiency of production plants and the quality of the final product. Consequently, companies that implement advanced solutions in production systems will have a competitive advantage in the future. The principles of Industry 4.0 can also be applied to shipyards to transform them into “smart shipyards” (Shipyard 4.0). The aim of this research is to implement an interactive approach by Internet of Things on a closed power-loop test bench equipped with sophisticated sensors that is specifically designed to test high-power thrusters before they are installed on high-speed crafts, which are used in passenger transport. The preliminary results of the proposed Internet of Things-platform demonstrates the efficacy of the decision-making support tool in improving the design of propulsion systems and increasing their efficiency compared to traditional systems.

Slamming load and hydroelastic structural response of bow flare areas of aluminium fast displacement crafts

The paper evaluates the response of an aluminium stiffened panel of a fast displacement craft under bow flare slamming loads by using three finite element methods: (1) a linear static analysis to calculate the structural elastic deformation and stress under the design load; (2) an independent analysis of the slamming load and the elastic structural response (a decoupled method); (3) a method that couples their interaction (a fully coupled method). These methods are compared to analyse the hydroelastic effect when predicting the structural loading and response. Similar results are obtained by the three methods and the linear static analysis based on design load evaluates with accuracy the local structural deformation and stress. The primary objective of the present work is to investigate the strength and safety of bow-flared structures when designing high-speed and fast displacement aluminium crafts subjected to slamming pressure loads. The influence of spray rail on the bow-flared slamming pressures and the effect of boundary conditions on the elastic structural responses are discussed.

Experimental modelling of local structure responses for high-speed planing craft in waves

The modelling of planing craft dynamics in waves and related fluid-structure interaction is a hard challenge due to the highly nonlinear, transient and stochastic nature of the whole process. This paper explores the prospectives of detailed experimental modelling of the local structure responses for high-speed planing craft in waves. A novel experimental setup is presented where a well-defined model structure is integrated into the hull bottom of a typical planing craft model. The model is instrumented for measuring strains in the model structure, related slamming pressures, craft rigid body motions and accelerations. The experimental setup is thoroughly described and motivated and crucial aspects of the setup are verified through testing in idealized static loading conditions and by modal analysis. The capabilities of the experimental setup are demonstrated through systematic experiments in regular waves. The most indicative results are presented and discussed in relation to corresponding results from time-domain simulations. The presented experimental modelling approach is concluded to enable uniquely detailed studies of the complete slamming related fluid-structure interaction process and provides a good tool for further research and development towards establishment of first principles-based methods for hydrodynamic and structure design of high-speed planing craft.

Numerical modelling of structure responses for high-speed planing craft in waves

The paper presents an approach for time-domain simulation of structure responses, along with hydromechanic and structure inertia loads and motions responses, for high-speed planing craft in waves. Hydromechanic loads and motion responses are calculated with a non-linear time-domain strip method. A pressure shape function is introduced which enables formulation of detailed slamming pressure distributions sequences from the section forces in the strip method simulations. Structure responses are calculated quasi-dynamically by applying the momentary distributed pressure loads on a global finite element representation of the hull structure with use of inertia relief. From the time series output extreme responses are determined by means of short-term statistics. Promising results are demonstrated in applications on a high-speed planing craft, where extreme values of simulated structure responses are compared with responses to uniform design pressures from classification rules and measured responses from full-scale trials. The approach is concluded to be a useful tool for further research which has potential to form the basis for establishment of a computationally efficient simulation-based design methodology. A corresponding experimental modelling approach is presented in a parallel paper.

Fracture Toughness and Microstructure of Gas Metal Arc Welded Plates of Aluminium Alloy 5083 Using Different Filler Wires and Heat Inputs

Aluminum alloys AA5083 is alloys which mostly used in the hull components of the ship and high-speed craft. Commonly gas metal arc welding (GMAW) is used for joining the construction. Welding strength especially cracks toughness, is very important on this welding due to the regular operation of the ship or high-speed craft. In this research, welding of aluminum alloys AA5083 with dimension 150 mm x 350 mm and thickness 15 mm and 20 mm, were carried out by gas metal arc welding using two difference filler metal ER5183 and ER5356, and 99% argon is used as shielding gas. The result of the experiment that the maximum value of excellent toughness was shown on welding with thickness plate 15 mm using filler metal ER5356 and heat input 7.8 kJ/cm.

Experimental investigation of the effect of a step and wedge on the performance of a high-speed craft in calm water and statistical analysis of its seakeeping in irregular waves

Analysis of the hydrodynamic performance of a high-speed craft in calm water and seakeeping in irregular waves have attracted the attention of many researchers. In the current paper, experimental tests have been conducted on three mono-hull high-speed crafts in calm water and in the presence of irregular waves. The overall geometry of the tested vessels is the same with a length of 2.64 m and a beam of 0.551 m. They only differ in the presence of a wedge or transverse step. These vessels are stepped vessels and bare vessels with no appendage. Different parameters of trim, rise-up, and resistance are measured in calm water. In addition, heave and pitch motions, fore acceleration, and the center of gravity are extracted as time series. The irregular wave, which is modeled in sea force of 3, has a height of 12 cm and a peak to peak time period of 1.66 s. The tests are conducted for five different speeds ranging from 4 m/s to 8 m/s (equivalent of longitudinal Froude numbers between 0.857 and 1.71). Comprehensive comparisons have been presented between the stepped, wedged, and bare hulls. Based on the obtained results, it is concluded that the stepped vessel has less resistance in calm water compared to the two other models. The trim and resistance of the stepped model are 20% and 3% less than those of the models with no appendage, respectively. In terms of stability, the bare hull is longitudinally unstable at 8 m/s speed. However, the other two models are stable at this speed. On the other hand, the wedge mounted vessel exhibits less motion and acceleration than the other two models in irregular waves. Furthermore, the bow acceleration of the stepped and wedged models is 9% and 18% lower than that of the model with no appendage, respectively.

Simulation of Air\u2013Water Interface Effects for High-speed Planing Hull

High-speed planing crafts have successfully evolved through developments in the last several decades. Classical approaches such as inviscid potential flow–based methods and the empirically based Savitsky method provide general understanding for practical design. However, sometimes such analyses suffer inaccuracies since the air–water interface effects, especially in the transition phase, are not fully accounted for. Hence, understanding the behaviour at the transition speed is of fundamental importance for the designer. The fluid forces in planing hulls are dominated by phenomena such as flow separation at various discontinuities viz., knuckles, chines and transom, with resultant spray generation. In such cases, the application of potential theory at high speeds introduces limitations. This paper investigates the simulation of modelling of the pre-planing behaviour with a view to capturing the air–water interface effects, with validations through experiments to compare the drag, dynamic trim and wetted surface area. The paper also brings out the merits of gridding strategies to obtain reliable results especially with regard to spray generation due to the air–water interface effects. The verification and validation studies serve to authenticate the use of the multi-gridding strategies on the basis of comparisons with simulations using model tests. It emerges from the study that overset/chimera grids give better results compared with single unstructured hexahedral grids. Two overset methods are investigated to obtain reliable estimation of the dynamic trim and drag, and their ability to capture the spray resulting from the air–water interaction. The results demonstrate very close simulation of the actual flow kinematics at steady-speed conditions in terms of spray at the air–water interface, drag at the pre-planing and full planing range and dynamic trim angles.

Experimental and Numerical Investigation of Stepped Planing Hulls in Finding an Optimized Step Location and Analysis of Its Porpoising Phenomenon

Stability of a high-speed craft is an essential matter, and porpoising is one of the most critical instabilities that could occur in some planing hulls due to inappropriate design. In this paper, the porpoising phenomenon and variation of step location yielding resistance reduction are studied through experimental and numerical methods. The investigated models include a single-step model and a nonstep model with the same general shape, but with different step location. The nonstep model is previously tested, but the single-step model is examined in the present study. The nonstep model experiences porpoising at 8 m/s speed, but the single-step model remains stable at the same speed. A three-dimensional CFD analysis is conducted using the finite volume method (FVM). On the contrary, the volume of fluid (VOF) scheme is used for free surface modeling, and the overset mesh technique is implemented within StarCCM+ software. The CFD results of total hydrodynamic resistance and dynamic trim angle are compared against the experimental data. The numerical results are in good agreement with the experimental data. Subsequently, ten different stepped models are simulated to examine their effects. The longitudinal distance between steps and aft of these models are in the range of 19 to 50 percent of the length of models. The obtained results show that as steps are located farther than aft, the models become more stable, and resistance increases due to trim reduction. Finally, the optimum location of the step is extracted with the aim of minimizing the resistance through the design of experiment (DOE) method. Based on the DOE method, it is observed that the sensitivity of the drag value to the step location is higher than the speed.

Basic Design of High-Speed Riverine Craft Made of Carbon Fiber Reinforced Polymer

Basic Design of High-Speed Riverine Craft Made of Carbon Fiber Reinforced Polymer

Efficacy Analysis of Thickness and Camber Size of Cross Section of the Stator on Hydrodynamic Parameters in Linear Jet Propulsion System

The linear jet propulsion system, unlike pump-jets which are widely used in underwater bodies, is installed inside a tunnel under the vessel and can be used for high-speed crafts, tugs, and service boats. However, this system has not received adequate attention by researchers, which is the subject of the current study. In the present paper, hydrodynamic performance of the linear jet propulsion system is numerically investigated. Accordingly, the Ansys-CFX software is utilized and RANS equations are solved using the SST turbulent model. The results of the proposed numerical model, in the form of thrust and torque coefficient as well as efficiency, are compared with available experimental data for a ducted propeller, and good compliance is achieved. Considering the importance of stator cross section on the performance of the linear jet propulsion system, the influence of thickness and camber size of the stator on linear jet propulsion systems are examined. Based on the numerical findings, it is determined that at constant advance ratio, with increasing thickness of stator, the efficiency increases. It is also observed that as the span length increases, the maximum and minimum of the pressure coefficient increase for different thicknesses. Furthermore, it is seen that positive and negative pressure coefficients decrease with an increase in foil thickness.