The prediction of wake wash in the towing tank

The wash or ship-generated waves from high speed craft has become a common subject in research and development of marine transportation. Since some time now the wake wash of high speed craft has become a problem in particular on inland or confined waterways. This wake wash has an impact on safety and environment such as bank/shoreline erosion, risk to people on shore and small boats in harbors and changes in the local ecology. This paper describes the results of model test of a high speed patrol, together with theoretical prediction of wake wash

Nonlinear Response of SemiSWATH Ship,Bow-diving, and Fin Stabilizer Effect in Following Seas

In this research, the response of a Semi-SWATH\ud (Small Waterplane Area) ship in following sea condition with\ud fins stabilizer was investigated. In the waves, a ship move\ud with periodic dynamic surge motion caused by the external sea\ud wave force and moment. In addition, in following seas with\ud high steep waves, the ship can surf, high pitch, bow-dive, and\ud lead the ship in the non-linear response. A numerical\ud simulation program in 3DOF (surge, heave and pitch) with\ud time varying model equation was developed to study the ship\ud responses. This study focuses on the effect of variation of\ud wave parameter to the ship response and the effects of fins\ud stabilizer; fixed and active. The numerical simulations were\ud validated with model tests in towing tank. Simulations results\ud showed that the dynamic ship response was stabilized\ud effectively and reduced pitch angle by active fins stabilizer\ud action

Experimental analysis on flow around fin assisted semi SWATH

Demand on High Speed Craft (HSC) is increasing due to development of inland transportation. Therefore, many analysis have been conducted to evaluate performance of this modern ship. One of the important analysis is calm water resistance test. Resistance component of the hull and wave pattern around the hull are obtained from the calm water test. These criteria are important in analyzing flow around hull, especially on wave interference between the hulls. In this paper, flow around hull has been studied for one model of Semi SWATH hull form with fin stabilizers installation by performing calm water resistance test in deep water. The fore fin angle is fixed to zero degree while the aft fin angle is varied to 0, 5 and 15 degree. The effects of fin angle to resistance criteria and flow around hull are investigated. Wave height has been recorded using longitudinal wave probe during resistance test. For each configuration, the investigation is conducted with range of Length Froude Number from 0.34 to 0.69. From the analysis, it is found that flow around the hull of Semi SWATH is affected by fin angle and the effect is various depend on the Froude numbe

Field measurement of fishing boats generated waves

Ship generated waves can cause banks erosion as well as disturbance on stationary boats. Studies have shown that the boat generated waves are dependent on and affected by environmental factors and vessel parameters. The main environmental factors are tidal and current direction, and for vessel parameters are speeds and hullforms. This paper describes a full-scale experimental work to measure wave heights and wave angle direction on boat generated waves. The measurement method used in this paper is based on the analysis of digital video recordings and image processing techniques

Mooring effect on wave frequency response of round shape FPSO

This paper presents the motions response of moored Round Shape FPSO model due to the wave effect. The proposed of this research is analyzed the possibility of model motion response affected by different mooring system attach to the model. Model experiment was applied in this research to collect motion data for the study. Besides, the numerical simulation using diffraction potential, diffraction potential with Morison Heave correction and ANSYS frequency domain study were also applied in this research to generate comparative data to the experimental results. To investigate the effect of the mooring system to motion response, the model experiment was firstly conducted by attached model scale catenary mooring lines to Round Shape FPSO model. After that, the experiment was repeated by attached model scale taut mooring lines to the same model. The results obtain from the regular wave experiment tests and numerical simulation test were presented in this paper. This research concluded that the mooring systems would not give significant effect to wave frequency motion response after compared the motion result obtain from model experiment conducted using different mooring system

Prediction of added resistance of ship due to regular head waves

This paper presents the added resistance of a 100m Product Tanker due to waves. It includes the study of influence of ship speed and wavelength to the added resistance. This work was carried out by theoretical calculation and model testing in towing tank. The method proposed by Gerritsma & Beukelmen was used in the theoretical calculation technique. This method required ship motion and hydrodynamic coefficients data as input, which was determined using Strip Theory. The model testing was carried out on a 3.382 m model in the towing tank 120m x 4m x 2.5m at the Universiti Teknologi Malaysia’s (UTM) Towing Tank in Skudai, Johore Bahru. Both of the techniques were investigated in three Froude number values, namely 0.21, 0.25 and 0.28. For each Froude number, the study was conducted at wavelength to model length ratio, Lw/Lm between 1.0 and 2.0. The outcomes from both experimental and theoretical calculations were also compared

Design aspects of catamarans operating at high speed in shallow water

The thesis describes the investigation into the design aspects of the high-speed displacement catamaran.  This work is presumably an extension of the existing database on the high-speed displacement hull form series namely the NPL series.  The experimental test programme has been extended in the current research to investigate the influence of bulbous bows on the high-speed displacement catamaran performance in deep and shallow water conditions.  Four bulbous bows have been developed by ranging bulbous bow’s projecting length, between 1.25% to 6.25% of the length of waterline.  These bulbous bows have been designed and faired to the parent hull, NPL5b or known as a Model 5b of the NPL Series, whilst the after body and the fore body from amidships to 0.3 Lpp are being kept unchanged.  However, the cross section parameter has been fixed at value 0.303 i.e. the ratio of the bulbous bow cross section area at forward perpendicular to the midship section area.  Measurements of total resistance, wash, trim and sinkage have been made up to a Froude number of unity in deep and shallow waters.  In addition to the calm water tests, these models were also tested in regular waves covering a wavelength to ship length ratio λ/L between 0.5 and 2.0 whilst the wave height was maintained at 0.030 m.  Measurements of added resistance in waves, pitch, hence and wash cuts were made.  The thin ship theory computer codes namely wave13d.for and wave3d3ss.for have been used to validate the measured wash cuts.</p

Design aspects of catamarans operating at high speed in shallow water

The thesis describes the investigation into the design aspects of the high-speed displacement catamaran. This work is an extension of the existing database on the high-speed displacement hull form series namely the NPL series. The experimental test programme has been extended in the current research to investigate the influence of bulbous bows on the high-speed displacement catamaran performance in deep and shallow water conditions. Four bulbous bows have been developed by ranging bulbous bow's projecting length, between 1.25% to 6.25% of the length of waterline. These bulbous bows have been designed and faircd to the parent hull, NPL5b or known as a Model 5b of the NPL Series, whilst the after body and the fore body from amidships to 0.3Lpp are kept unchanged. However, the cross section parameter has been fixed at value 0.303 i.e. the ratio of the bulbous bow cross section area at forward perpendicular to the midship section area. Measurements of total resistance, wash, trim and sinkage have been made up to a Froude number of unity in deep and shallow water. In addition to the calm water tests, these models were also tested in regular waves covering a wavelength to ship length ratio AIT between 0.5 and 2.0 whilst the wave height was maintained at 0.030 m. Measurements of added resistance in waves, pitch, heave and wash cuts were made. Thin ship theory computer codes namely wavel3d.foT and wave3d3ss.foT have been used to validate the measured wash cuts. It was found that the experimental and numerical investigations provide a better understanding of the basic physics of wash, resistance and seakeeping of high speed displacement catamarans fitted with bulbous bows operating in deep and shallow water. The results of the systematic experimental investigation with respect to the influence of bulbous bows on wash, resistance and seakeeping provide invaluable information with a view to developing design guidance at the preliminary design phase and for validation purposes

A review of muslim maritime tradition

The ocean covers more than 75% of the earth surface. This vast expanse of water promises a wealth of opportunities as well as challenges. This paper describes a historical perspective of development of maritime ventures in the Islamic World from the time of the Prophet (pbuh) until the present day. The expansion of the Muslim caliphate entailed among others rapid growth in communication and transport system as well as the need for a well-organised naval fleet. The peak of Muslim naval power was during the rule of the Ottoman Empire when their warships held sway over the Mediterranean, the Red Sea and parts of the Indian Ocean. A survey of the present status of maritime military, commercial, education and R&D capacity in Muslim countries is presented and proposals put forward for improving collaboration in this field

Elemen reka bentuk kapal

Buku ini mengandungi beberapa bab iaitu kandungan: prakata, glosari, bab 1 faktor-faktor dalam reka bentuk kapal, keperluan pemilik, corak perdagangan, bab 2 parameter reka bentuk asas, masalah dalam reka bentuk kapal, reka bentuk awal, bab 3 berat kapal-ringan dan anggaran kuasa, penilaian berat kapal-ringan, kaedah untuk berat keluli, bab 4 anggaran muatan kargo, bab 5 ciri-ciri hidrostatik dan kestabilan, pekali bungkah dan sebagainya momen lentur, kaedah membuat anggaran, bab 6 reka bentuk badan kapal, luas keratan tenggelem, luas peminggang, bab 7 penginapan anak kapal dan penumpang, bab 8 pengkelasan, spesifikasi dan kontrak, bab 9 lampung bebas, pemetakan dan tannan, bab 10 pemilihan terhadap jentera pendorong, kuasa stim, disel, bab 11 kuasa dan kipas, bab 12 penyelidikan kapal dan kejuruteraan marin