Development of Low Wake Wash Hull Form

2015 ◽  
Vol 74 (5) ◽  
Author(s):  
O. B. Yaakob ◽  
Yasser M. Ahmed ◽  
Mohd M. Abd Rahman ◽  
A. H. Elbatran
Keyword(s):  
Wave Height ◽  
Research Work ◽  
Ship Design ◽  
Significant Issue ◽  
Hull Form ◽  
Towing Tank ◽  
Technology Center ◽  
Marine Technology

Wake wash has become a significant issue in the ship design industry due to its impact on the environment in terms of erosion of natural shoreline wetlands. Many ideas for reducing wake wash have been introduced. This research work presents the development of a low wake wash catamaran hull form. In particular, the study is focused on the effectiveness of specially designed fin in order to reduce the wake wash produced by the ship. The fin was attached vertically along the centerline of the catamaran model and the model was tested in the towing tank of Marine Technology Center (MTC) to assess its wake wash. The fin was located at three different positions, which are at bow, center and stern of the ship. The results based on wave height measurements at the various fin locations showed that the fin located at the stern position produces lower wake wash compared to other positions.

CFD Application in Resistance Analysis for Advanced Semi-SWATH Vehicle

2013 ◽  
Vol 465-466 ◽  
pp. 44-49
Author(s):  
Arifah Ali ◽  
Adi Maimun ◽  
Y.M. Ahmed
Keyword(s):  
High Speed ◽  
Computational Simulation ◽  
Experimental Result ◽  
Hull Form ◽  
Hydrodynamic Analysis ◽  
Towing Tank ◽  
Resistance Analysis ◽  
Marine Technology ◽  
Design Characteristics ◽  
Transportation Research

Demand on High Speed Craft (HSC) is increasing due to development of inland transportation. Research of advanced HSC have been in good progress as the design characteristics of the vessel have much to be discovered. One of the important analyses for HSC is hydrodynamic analysis which includes resistance analysis to maintain good performance with low fuel consumption. In this paper, resistance and flow pattern of one type of HSC, Semi-Small Waterplane Area Twin Hull (SWATH) with advanced design is analyzed. In current research, Computational simulation using CFD (Computational Fluid Dynamics) is performed with RANSE code in order to obtain catamaran performance in resistance. Therefore, the accuracy of CFD for Semi-SWATH is analyzed by comparing the simulation result with experimental result in both catamaran and SWATH mode. Volume of Fluid (VOF) Method is applied to analysis the effect of free surface on the twin hull. For both configurations, the investigation was conducted on the hull form with constant separation length and at different Froude Number from 0.31 to 0.68. The results were compared to available experimental results which were conducted in towing tank at UTM Marine Technology Center.

THE INFLUENCE OF CENTRE BOW LENGTH ON SLAMMING LOADS AND MOTIONS OF LARGE WAVE-PIERCING CATAMARANS

2021 ◽  
Vol 160 (A1) ◽  
Author(s):  
J R Shahraki ◽  
G A Thomas ◽  
M R Davis
Keyword(s):  
Wave Height ◽  
Full Scale ◽  
Bending Moments ◽  
Regular Waves ◽  
Large Wave ◽  
Towing Tank ◽  
Segmented Model ◽  
Model Experiments ◽  
Slamming Load ◽  
Wave Induced

The effect of various centre bow lengths on the motions and wave-induced slamming loads on wave-piercing catamarans is investigated. A 2.5 m hydroelastic segmented model was tested with three different centre bow lengths and towed in regular waves in a towing tank. Measurements were made of the model motions, slam loads and vertical bending moments in the model demi-hulls. The model experiments were carried out for a test condition equivalent to a wave height of 2.68 m and a speed of 20 knots at full scale. Bow accelerations and vertical bending moments due to slamming showed significant changes with the change in centre bow, the longest centre bow having the highest wave-induced loads and accelerations. The increased volume of displaced water which is constrained beneath the bow archways is identified as the reason for this increase in the slamming load. In contrast it was found that the length of centre bow has a relatively small effect on the heave and pitch motions in slamming conditions.

Effect of Shallow Water on a Mathematical Hull at High Subcritical and Supercritical Speeds

1986 ◽  
Vol 30 (02) ◽  
pp. 85-93
Author(s):  
A. Millward ◽  
M. G. Bevan
Keyword(s):  
Shallow Water ◽  
Wave Theory ◽  
Hull Form ◽  
Towing Tank ◽  
Resistance Peak ◽  
Good Agreement ◽  
Made In

Experiments have been made in a towing tank to measure the resistance of a mathematical hull form in deepwater and in shallow water at high subcritical and supercritical speeds. The data have been compared with calculations using linearized wave theory for the same hull shape. The results have shown fairly good agreement, with the greatest differences occurring near the subcritical resistance peak.

SHAFT LOADS ON AZIMUTH PROPULSORS IN OBLIQUE FLOW AND WAVES

2021 ◽  
Vol 153 (A1) ◽  
Author(s):  
H Amini ◽  
S Steen
Keyword(s):  
Mechanical Design ◽  
Bending Moment ◽  
Ship Hull ◽  
Propeller Shaft ◽  
Towing Tank ◽  
Oblique Flow ◽  
Straight Line ◽  
Calm Water ◽  
Bending Loads ◽  
Marine Technology

A range of model experiments have been carried out in calm water and waves for an oil spill vessel model with twin tractor azimuth thrusters at different heading angles and advance coefficients in the large towing tank at the Marine Technology Centre in Trondheim, Norway. Propeller shaft bending loads have been measured using a shaft dynamometer capable of measuring all shaft side force and bending moment components as well as propeller torque and thrust. The results include the loads on the propeller shaft with and without the presence of a ship hull model at the same heading angles and advance velocities in order to study the wake influence from the ship hull on the hydrodynamic loads. Results show that the ship hull wake has a much stronger effect on the propeller loads when the propeller is azimuthed outward from the ship hull centreline than inward. Measurements from the experiments in waves are also presented for the same thruster model in a straight-line course for both the head and following sea states under different wave conditions. Larger bending loads are found in head sea conditions compared with the following sea conditions. Generally it is found that the shaft bending loads and lateral forces are quite large, which is important to consider in the mechanical design layout and for dimensioning of components.

Experimental Analysis of Five Keel-Hull Combinations

1985 ◽  
Author(s):  
J. Gerritsma ◽  
J. A. Keuning
Keyword(s):  
Experimental Analysis ◽  
Model Tests ◽  
Experimental Results ◽  
Forward Speed ◽  
Hull Form ◽  
Towing Tank ◽  
Side Force ◽  
Performance Predictions

Model tests with five different keels in combination with one particular hull form have been carried out in the Delft Towing Tank. The variations include a plain deep keel, a keel-centre board, a plain restricted draft keel,a "Scheel" keel and a "winglet" keel. Based on the experimental results performance predictions are given for a 63 ft yacht for windspeeds up to 25 knots. The measured side force and resistance as a function of heeling angle, leeway angle and forward speed are used to analyse the relative merits of the considered keel-hull combinations.

scholarly journals Manoeuvring forces on azimuthing podded propulsor model

2007 ◽  
Vol 14 (2) ◽  
pp. 3-8 ◽  
Author(s):  
Maciej Reichel
Keyword(s):  
Deflection Angle ◽  
Open Water ◽  
Ship Design ◽  
Experimental Results ◽  
Research Centre ◽  
Test Program ◽  
Towing Tank ◽  
Carrier Model ◽  
Podded Propulsor ◽  
Cavitation Tunnel

Manoeuvring forces on azimuthing podded propulsor model This paper presents the preliminary part of comprehensive manoeuvring open-water tests of a gas carrier model. The paper focuses on open water experiments with an azimuthing podded propulsor. The test program was carried out in the cavitation tunnel and the large towing tank of Ship Hydromechanics Division, Ship Design and Research Centre, Gdańsk. The pod was tested as a pushing unit with a 161.3 mm diameter propeller. Steering forces were measured in the range of advance coefficient from 0.0 to 0.8 combined with the range of deflection angles from -45° up to +45°. Measurements on the pod without propeller were also performed. The experiment results are presented in the form of non-dimensional coefficients in function of advance coefficient and deflection angle. Analysis of the experimental results and the conclusions are presented.

A Tribute to the Extraordinary Research Work Within the Domain of Fatigue and Fracture of Offshore and Ship Structures Carried Out by Prof. Stig Berge and Per Jahn Haagensen at the Norwegian University of Science and Technology

2017 ◽  
Author(s):  
Agnes Marie Horn ◽  
Kenneth A. Macdonald
Keyword(s):  
Science And Technology ◽  
Research Work ◽  
Active Member ◽  
International Institute ◽  
Emeritus Professor ◽  
Ship Structures ◽  
Fatigue And Fracture ◽  
Marine Technology ◽  
Offshore Industry ◽  
Historical Contribution

The motivation of this paper is to highlight the importance of the work carried out during the last decade by Prof. Haagensen and Prof. Berge at the Norwegian University of Science and Technology NTNU, with the aim to inspire and motivate young engineers to continue their important and valuable research within fatigue and fracture. This paper will focus on their historical contribution to the research within fatigue and fracture of offshore and ship structures. Stig Berge is a professor of Marine Technology at the Norwegian University of Science and Technology NTNU. He has spent his academic carrier focusing on fatigue of offshore and ship structures; he has published more than 70 papers and articles in well-known journals and conferences since 80’s. Per Jahn Haagensen is currently an Emeritus professor at Department of Mechanical Engineering and Logistic Faculty of Technology. He has spent his whole research carrier within fatigue and fracture related topics mainly for the offshore industry. He is especially known for the different fatigue improvement methods which have been developed since the 90’s. He has until recently been an active member of the International Institute of Welding (IIW). This article aims to present their main findings and conclusions from their long academic carrier. While the authors have strived to convey in a single paper an overview of the careers and important contributions, the Professors themselves may well have chosen to place a different emphasis on their work.

scholarly journals THE RESISTANCE ASPECT OF FISHING BOAT SKIPJACK POLE AND LINE

2021 ◽  
Vol 4 ◽  
pp. 1-7
Author(s):  
Wolter R Hetharia ◽  
Eliza R De Fretes ◽  
Reico H Siahainenia
Keyword(s):  
Model Test ◽  
Ship Design ◽  
Full Scale ◽  
Suitable Method ◽  
Design Phase ◽  
Towing Tank ◽  
Model Scale ◽  
Fishing Boat ◽  
Fishing Vessels ◽  
The Difference

The operation of fishing vessels skipjack pole and line contributes in catching tuna and skipjack fishes particularly in Indonesian waters. A previous study conducted by the authors found that there was no suitable method provided for the resistance computation atearly ship design phase. Besides, there was aninitial trim existed on the vessel during the operation which contributes for the resistance. The purpose of the study is to find the difference of resistance between the model test and the existing methods. The study was executed also to find the effect of initial trim of the vessel. The study began with collecting the database of a parent ship then to develop and transform into a model-scale for testing purpose in the towing tank. The results of model test were converted to the full-scale vessel. The resistance of full-scale vessel was computed based on the Holtrop and Guldhammer methods. The result of full-of resistance obtained from the model test and the methods were collected, evaluated and compared. The results showed the difference of the resistance for all methods. The result of model test is greater 21 % than that of Holtrop method at the service speed of 10 knots. Meanwhile, the result of model test is lower 14 % than that of Gulhammer method at the same speed. In addition, at the speed of 10 knots the initial trim of 0.5O increase 5 % ofthe resistance, the initial trim of 1O increase 10 % of resistance and the initial trim of 2O increase 16 % of resistance compared to the vesselwithout initial trim. In conclusion, the existing resistance methods are not suitable to be applied for skipjack pole and line fishing vessels. In addition, the initial trim contributes to increase the resistance and should be avoided during the vessel operation.

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