The Experts below are selected from a list of 78 Experts worldwide ranked by ideXlab platform

Neil Bose - One of the best experts on this subject based on the ideXlab platform.

  • On the macro hydrodynamic design of highly efficient medium-speed catamarans with minimum resistance
    International Journal of Maritime Engineering, 2012
    Co-Authors: M Haase, G Davidson, Giles Thomas, Jonathan Binns, Neil Bose, S Friezer
    Abstract:

    A new class of fuel-efficient and environmentally friendly twin-hull vessels is currently under development. Compared to high-speed catamarans, a significant reduction in speed combined with an increase in deadweight tonnes will lead to a highly efficient medium-speed catamaran design. Recently-built conventional and high-speed ferries are compared to each other in terms of length, speed, deadweight and transport efficiency to classify the new design. The goal of this study is to find a preliminary macro design point for minimum total resistance by considering the main particulars of the catamaran vessel: block Coefficient, Prismatic Coefficient and slenderness and separation ratios of the demihulls. Publications containing recommendations towards the optimum hull form parameters for moderate Froude numbers are reviewed and existing experimental data analysed to identify parameters for this new class of vessel. Designs with varied L/BOA-ratios and constant deck area are compared to find configurations of low total resistance for carrying a nominated deadweight at a particular speed, the associated change of the light ship weight has been taken into account. Two different model test series of catamaran models have been considered and their resistance curves agreed to each other. Recommendations are made; with the most important being the vessel should not exceed a speed of Fr = 0.35, with optimal Prismatic Coefficients around C P ≈ 0.5 and low transom immersion. This study presents the preliminary design of medium-speed single and twin-hull vessels for operations close to hump speed.

  • On the design and resistance prediction of large medium-speed catamarans
    2012
    Co-Authors: M Haase, G Davidson, Giles Thomas, Jonathan Binns, Neil Bose
    Abstract:

    Medium-speed catamarans are under development as a new class of vessels to meet requirements for highly efficient sea transportation with a low environmental impact. A reduction in service speed and an increase in deadweight will lead to a high transport efficiency. Compared to current high-speed catamarans, these new vessels will operate at a transitional speed range between those of high-speed craft and conventional displacement ships. In this paper, design guidelines to choose appropriate hull form parameters for medium speed catamarans with minimum resistance are derived and a preliminary design is made. Most important these vessels will operate at Froude numbers of Fr = 0.35 and have a relatively low Prismatic Coefficient of Cp 「 0.5 in conjunction with a low transom immersion. To correctly predict the calm water resista.nce, different methods to predict the calm water resistance of such vessels are discussed, whereas viscous free-surface flow simulat ions are most promising. It is shown that they are capable of predicting the hydrodynamic behaviour of mediumspeed catamarans, such as drag force , trim and sinkage within an acceptable range of accuracy.

Da Kui Feng - One of the best experts on this subject based on the ideXlab platform.

  • Prediction of Surface Ship's Residual Resistance Coefficient Using Neural Networks
    Advanced Materials Research, 2013
    Co-Authors: Li Hua Song, Zhiguo Zhang, Xianzhou Wang, Da Kui Feng
    Abstract:

    The Holtrop method, which provides a prediction of the components of surface ships total resistance, is widely used at ships initial design stage for estimating the resistance. In this paper a neural network model which performs the same role as the Holtrop method is presented to predict the residual resistance. A multilayer perceptron has been trained with the data generated by the Holtrop method to learn the relationship between the input (length-displacement ratio, Prismatic Coefficient, breadth-draft ratio and Froude number) and the target variable (the residual resistance Coefficient). The results of this model have been compared against those provided by the Holtrop method and it is found that the quality of the prediction is improved over the entire range of data. The neural network provides an accurate estimation of the residual resistance with the Froude number and the hull geometry Coefficients as variables.

M Haase - One of the best experts on this subject based on the ideXlab platform.

  • On the macro hydrodynamic design of highly efficient medium-speed catamarans with minimum resistance
    International Journal of Maritime Engineering, 2012
    Co-Authors: M Haase, G Davidson, Giles Thomas, Jonathan Binns, Neil Bose, S Friezer
    Abstract:

    A new class of fuel-efficient and environmentally friendly twin-hull vessels is currently under development. Compared to high-speed catamarans, a significant reduction in speed combined with an increase in deadweight tonnes will lead to a highly efficient medium-speed catamaran design. Recently-built conventional and high-speed ferries are compared to each other in terms of length, speed, deadweight and transport efficiency to classify the new design. The goal of this study is to find a preliminary macro design point for minimum total resistance by considering the main particulars of the catamaran vessel: block Coefficient, Prismatic Coefficient and slenderness and separation ratios of the demihulls. Publications containing recommendations towards the optimum hull form parameters for moderate Froude numbers are reviewed and existing experimental data analysed to identify parameters for this new class of vessel. Designs with varied L/BOA-ratios and constant deck area are compared to find configurations of low total resistance for carrying a nominated deadweight at a particular speed, the associated change of the light ship weight has been taken into account. Two different model test series of catamaran models have been considered and their resistance curves agreed to each other. Recommendations are made; with the most important being the vessel should not exceed a speed of Fr = 0.35, with optimal Prismatic Coefficients around C P ≈ 0.5 and low transom immersion. This study presents the preliminary design of medium-speed single and twin-hull vessels for operations close to hump speed.

  • On the design and resistance prediction of large medium-speed catamarans
    2012
    Co-Authors: M Haase, G Davidson, Giles Thomas, Jonathan Binns, Neil Bose
    Abstract:

    Medium-speed catamarans are under development as a new class of vessels to meet requirements for highly efficient sea transportation with a low environmental impact. A reduction in service speed and an increase in deadweight will lead to a high transport efficiency. Compared to current high-speed catamarans, these new vessels will operate at a transitional speed range between those of high-speed craft and conventional displacement ships. In this paper, design guidelines to choose appropriate hull form parameters for medium speed catamarans with minimum resistance are derived and a preliminary design is made. Most important these vessels will operate at Froude numbers of Fr = 0.35 and have a relatively low Prismatic Coefficient of Cp 「 0.5 in conjunction with a low transom immersion. To correctly predict the calm water resista.nce, different methods to predict the calm water resistance of such vessels are discussed, whereas viscous free-surface flow simulat ions are most promising. It is shown that they are capable of predicting the hydrodynamic behaviour of mediumspeed catamarans, such as drag force , trim and sinkage within an acceptable range of accuracy.

Australian Maritime - One of the best experts on this subject based on the ideXlab platform.

  • WINDWARD PERFORMANCE OF THE AME CRC SYSTEMATIC YACHT SERIES
    1998
    Co-Authors: Bruce Mcrae, Australian Maritime, Jonathan R. Binns, Kim Klaka, Dovell Pty
    Abstract:

    SUMMARY Since 1994 the Australian Maritime Engineering Cooperative Research Centre (AME CRC) has conducted an extensive set of towing tank experiments and theoretical predictions for calm and rough water, on a series of 11.3 metre IMS style racing yacht hulls with varying form parameters. In collaboration with Murray, Burns & Dovell (MBD), the AME CRC has developed a Velocity Prediction Program (VPP), and experimental procedures, with the intention of providing performance predictions to the highest international standards. A theoretical study has also been undertaken using the AME CRC developed nonlinear vessel motions program, SEALAM. The AME CRC systematic series for yachts is comprised of five “mini-series”, corresponding to one series for each hull parameter investigated so far: length to displacement ratio; beam to draft ratio; Prismatic Coefficient; LCB - LCF separation, and; stern overhang. The parent hull is a development of the Delft Systematic Yacht Hull Series II. All the one-fifth scale models represent realistic yacht forms that could reasonably be expected to race as 11.3 metre IMS designs. Rough water test conditions were representative windward sailing scenarios corresponding to 6.5 knots full scale, 20 degrees heel and 3 degrees yaw. This paper is written in two parts. Firstly, the paper will deal with the experimental procedures used by the AME CRC, highlighting the sources of errors and their magnitudes. The repeatability of the experiments has been exhaustively tested over three years, and the results of these studies are presented in this paper. The second part of this paper explains some of the results directly relating to the seakeeping predictions and experiments that have been conducted on the series of ten yachts over the past three years. To illustrate the accuracy of the results achieved, a comparison between the performance predicted from the investigation of Prismatic Coefficient variation, and that calculated from the 1996 version of the IMS VPP is also presented.

  • Prediction of ship resistance by a blended theoretical and experimental method
    1995
    Co-Authors: Australian Maritime
    Abstract:

    The prediction of the total resistance of a ship is generally based on considering it to be a simple sum of the viscous resistance and the wave resistance. This is known as the Froude hypothesis and is used in the process of extrapolating the drag data from towing-tank tests on ship models to the prototype vessel. During these experiments, one usually approximates the viscous resistance by the standard frictional resistance on the equivalent flat plate multiplied by the so-called form factor, and whose value is known for various ship types. This approach for predicting full-size ship resistance is practical but obviously has the deficiency that a model has to be built for each prototype of interest and the resulting tank tests are time consuming. On the other hand, purely theoretical calculations of the wave resistance, using, for example, the Michell theory, require relatively little computer time and give an excellent portrayal of the overall variation of the vessel resistance as a function of forward speed. Unfortunately, there are sufficient differences between this theory and the measured results to make this method impractical for design purposes. The proposal suggested here is to use a data bank of experimental resistance results to modify the theoretical predictions. It is demonstrated that the technique will produce remarkably accurate resistance predictions and can take into account the following effects: water depth, spacing between the demihulls in the case of a catamaran, banks in the case of laterally restricted water (such as a canal or river), and the Prismatic Coefficient (the measure of the longitudinal distribution of the volume of the

Muhsin Aydm - One of the best experts on this subject based on the ideXlab platform.

  • Influence of Design Parameters on Vertical Motions of Trawler Hull Forms in Head Seas
    Marine Technology and Sname News, 1997
    Co-Authors: Abdi Kukner, Muhsin Aydm
    Abstract:

    The influence of ship length, length to beam ratio, beam to draft ratio, Prismatic Coefficient, non-dimensional radius of gyration and Froude number upon significant amplitude of coupled heaving and pitching motions of trawler hull forms for six different sea states has been studied. For this purpose, 540 trawler hull forms have been generated from Doust trawler series to cover appropriate ranges of the design parameters. Seakeeping behavior of these forms has been studied by using an established ship motion computer program and regression models of significant seakeeping events have been derived. Through this study, it is believed that a method has been produced for the seakeeping evaluation of trawler forms during the early design stages, hence allowing for the design of safer and more seakindly trawler designs.