The Windward Performance of Yachts in Rough Water

1999 ◽  
Author(s):  
Jonathan Binns ◽  
Bruce McRae ◽  
Giles Thomas
Keyword(s):  
Research Program ◽  
Length Ratio ◽  
Added Resistance ◽  
Hull Form ◽  
Model Experiments ◽  
Theoretical Predictions ◽  
Rough Water

A 5 year research program to investigate the effect of realistic hull form parameters on the added resistance of a yacht in waves is nearing completion. Model experiments and theoretical predictions were carried out and the results are discussed in this paper. Five hull form parameters have been investigated so far, they are: 1. stem overhang; 2. LCB-LCF separation; 3. prismatic coefficient; 4. displacement length ratio and 5. beam draft ratio.

The Performance of Sailing Yachts in Oblique Seas

1974 ◽  
Vol 11 (04) ◽  
pp. 383-392
Author(s):  
David R. Pedrick
Keyword(s):  
Wave Length ◽  
Added Resistance ◽  
Regular Waves ◽  
Sea State ◽  
Hull Form ◽  
Rough Water ◽  
Rational Procedure ◽  
The Difference ◽  
Relationship Of ◽  
The Relationship

The difference in the effects of rough water on similar sailing yachts has been one of the intriguing puzzles that sailors, designers, and researchers have long tried to understand. It is not uncommon for two yachts of equal performance in smooth-sea conditions to have their speed or pointing ability reduced by different amounts when encountering waves. To investigate the causes of such behavior, it is important to have a rational procedure to analyze how changes in hull form, weight distribution, rig, and other design features affect the speed and motions of sailing yachts. This paper discusses the relationship of wind to rough water and of motions and added resistance to wave length and height. It then describes a procedure to predict motions, sailing speed, and speed-made-good to windward in realistic windward sailing conditions. The procedure utilizes results of heeled and yawed model tests of 12-metre yachts in oblique regular waves to predict performance in a Pierson-Moskowitz sea state corresponding closely to the equilibrium true wind speed.

Comparison of Experimental Towing Test and CFD Analysis of a Bare Hull Model on the Surface

2021 ◽  
Vol 163 (A3) ◽  
Author(s):  
Thu Han Tun ◽  
Ye Thet Htun ◽  
Aung Khaing Min
Keyword(s):  
Model Test ◽  
Surface Resistance ◽  
Surface Condition ◽  
Wave Formation ◽  
Complex Nature ◽  
Cfd Analysis ◽  
Cfd Simulations ◽  
Hull Form ◽  
Model Experiments ◽  
Key Aspects

In designing submarines, hull form selection, resistance, and powering are key aspects. The bare hull form of a submarine can be considered according to five parameters. Surface resistance is important should it be necessary to operate at relatively high Froude Numbers. Due to the complex nature of the flow around the hull, model experiments are still the most reliable approach to determining surface resistance. CFD simulations enable surface condition analysis using FINEMarine. The towing mechanism must be taken into account and so this was designed to fix the pitch motion and measure the hydrodynamic forces. This paper outlines the towing method, comparing the model test and the CFD results, as well as providing a comparison of wave formation from the towing test and the CFD results. The results show that resistance increased significantly above a model speed of 1.4 m/s. Furthermore, above this speed, as the resistance of the model rose, the downforce gradually decreased.

Predicting Hydrodynamic Behavior of Small-Waterplane-Area Twin-Hull Ships

1981 ◽  
Vol 18 (01) ◽  
pp. 69-75
Author(s):  
Edward Numata
Keyword(s):  
Design Process ◽  
Water Resistance ◽  
Experimental Techniques ◽  
Hydrodynamic Behavior ◽  
Hull Form ◽  
Early Stages ◽  
Rough Water

Existing naval and commercial small-waterplane-area, twin-hull (SWATH) vessels are described along with the reasons for choosing this type of hull configuration. The effects of changes in hull form and proportions on smooth water resistance and motions in rough water are examined. Analytical and experimental techniques presently available for use in the design process are discussed. Simple relationships for use in predicting resistance and seakeeping behavior in early stages of design are presented.

A Numerical Study on Correlation Between the Bow Design Parameters and Added Resistance Using the Design of Experiments

2016 ◽  
Author(s):  
Gwan Hoon Kim ◽  
Hyun Joon Shin ◽  
Jeonghwa Seo ◽  
Shin Hyung Rhee
Keyword(s):  
Design Of Experiments ◽  
Numerical Simulations ◽  
Numerical Study ◽  
Design Parameters ◽  
Added Resistance ◽  
Hull Form ◽  
Entrance Angle ◽  
Wave Condition ◽  
Added Resistance In Waves ◽  
Bulbous Bow

In this study, numerical computation was carried out for evaluating the effects of the design parameter variations on the added resistance of Aframax tanker in head seas. The design of experiments (DOE) was used to efficiently conduct the numerical simulations with the hull form variations and save computational resources. A computational fluid dynamics (CFD) code based on the continuity and Reynolds averaged Navier-Stokes (RANS) equation was used for the numerical simulation. The simulation was performed in a short wave condition where the wave length was half of the ship length, which is expected to be most frequent in the vessel operation. Five design parameters of fore-body hull form were selected for the variations: design waterline length (DWL), bulbous bow height (BBH), bulbous bow volume (BBV), bow flare angle (BFA) and bow entrance angle (BEA). Each parameter had two levels in the variations, thus total 32 cases were designed initially. The results of the numerical simulations were analyzed statistically to determine the main effects and correlations in the five design parameters variations. Among them, the most significant parameter that influences on the added resistance in waves was DWL, followed by BBV and BEA. The other parameters had little effects on the added resistance in waves. By the computations, it was revealed that Extending DWL and decreasing BEA promoted the reflection of waves more toward the side than forward. In addition, there existed two-way interactions for the following two-factor combinations: DWL-BFA, DWL-BEA, DWL-BBV, BBH-BBV.

A Multi-Level Approach to the Prediction of the Added Resistance and Powering of Ships in Waves

2019 ◽  
Author(s):  
Shukui Liu ◽  
Apostolos Papanikolaou ◽  
Peiyuan Feng ◽  
Sheming Fan
Keyword(s):  
Asymptotic Formula ◽  
Empirical Formula ◽  
Ship Design ◽  
Level Of Detail ◽  
Added Resistance ◽  
Hull Form ◽  
Computational Tools ◽  
Multi Level ◽  
Design Software ◽  
Semi Empirical

Abstract In this paper, we present a multi-level fidelity approach and associated computational tools for the prediction of the added resistance of various types of ships in waves. Employed methods include a fully empirical formula, a semi-empirical asymptotic formula, a potential flow, 3D panel method and a CFD code. Each of them requires a different level of detail for the hull form and this enables the application to various practical scenarios. The developed software tools are here validated against recently obtained model experiments data from MARIC. Developed tools are now integrated in the design software platform of MARIC and are used in the optimisation of ship design.

Numerical Analysis of the Influence of Above-Water Bow Form on Added Resistance Using Nonlinear Slender Body Theory

2005 ◽  
Vol 49 (03) ◽  
pp. 191-206
Author(s):  
Hajime Kihara ◽  
Shigeru Naito ◽  
Makoto Sueyoshi
Keyword(s):  
Three Dimensional ◽  
Wave Force ◽  
Slender Body ◽  
Added Resistance ◽  
Slender Body Theory ◽  
Hull Form ◽  
Nonlinear Properties ◽  
Head Waves ◽  
The Time Domain ◽  
Body Theory

A nonlinear numerical method is presented for the prediction of the hydrodynamic forces that act on an oscillating ship with a forward speed in head waves. A "parabolic" approximation of equations called "2.5D" or "2D+T" theory was used in a three-dimensional ship wave problem, and the computation was carried out in the time domain. The nonlinear properties associated with the hydrostatic, hydrodynamic, and Froude-Krylov forces were taken into account in the framework of the slender body theory. This work is an extension of the previous work of Kihara and Naito (1998). The application of this approach to the unsteady wave-making problem of a ship with a real hull form is described. The focus is on the influence of the above-water hull form on the horizontal mean wave force. Comparison with experimental results demonstrates that the method is valid in predicting added resistance. Prediction of added resistance for blunt ships is also shown by example.

Sailing Yacht Performance in Calm Water and in Waves

1993 ◽  
Author(s):  
J. Gerritsma ◽  
J. A. Keuning ◽  
A. Versluis
Keyword(s):  
Model Experiment ◽  
Irregular Waves ◽  
Current Interest ◽  
Added Resistance ◽  
Hull Form ◽  
Wide Range ◽  
Calm Water ◽  
Added Resistance In Waves ◽  
Sailing Yacht ◽  
Calculated Analysis

The Delft systematic Yatch Hull Series has been extended to a total of 39 hull form variations, covering a wide range of length displacement ratios and other form of parameters. The total set of model experiment results, upright and heeled resistance as well as sideforce and stability, had been analysed and polynomial expressions to approximate these quantities are presented. In view of the current interest in the performance of sailing yachts in waves, the added resistance in irregular waves of 8 widely different hull variations has been calculated. Analysis of the results shows that the added resistance in waves strongly depends on the product of displacement-length ratio and the gyradius of the pitching motion.

scholarly journals Added Resistance in Waves and Amplitude Function Expressing a Ship Hull Form

2008 ◽  
Vol 8 (0) ◽  
pp. 163-169 ◽  
Author(s):  
Shigeru Naito ◽  
Mariko Kuroda ◽  
Hisahumi Yoshida ◽  
Takehiro Ikeda
Keyword(s):  
Ship Hull ◽  
Added Resistance ◽  
Amplitude Function ◽  
Hull Form ◽  
Added Resistance In Waves

The Performance of Sailing Yachts in Oblique Seas

1974 ◽  
Author(s):  
David R. Pedrick
Keyword(s):  
Wind Speed ◽  
Weight Distribution ◽  
Wave Length ◽  
Added Resistance ◽  
Regular Waves ◽  
Sea State ◽  
Rough Water ◽  
Rational Procedure ◽  
Relationship Of ◽  
The Relationship

Differences in the effects that rough water has on similar sailing yachts has been one of the intriguing puzzles that sailors, designers, and researchers have long tried to understand, It is not uncommon that two yachts whose performance is equal in smooth sea conditions will have their speed or point­ing ability reduced by different amounts when encountering waves, To investigate the causes of such behavior, it is important to have a rational procedure to analyze how changes in hullform, weight distribution, rig, and other design features affect the speed and motions of sailing yachts. This paper discusses the relationship of wind to rough water and of motions and added resistance to wave length and height, It then describes a procedure to predict motions, sailing speed, and speed-made-good to windward in realistic windward sailing conditions, The procedure utilizes results of heeled and yawed model tests of twelve meter yachts in oblique regular waves to predict performance in a Pierson-Moskowitz sea state corresponding closely to the equilibrium true wind speed.

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