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

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

Investigation of wake wash in the towing tank

In recent years, the demand for high speed craft has increased significantly. The wave resistance plays an important role in total resistance and power prediction, which influence the design. Additionally, wake wash generated by high-speed crafts is also important to the design concept due to its impact on safety and environment such as beach/bank erosion, risk to people on shore and small boats in harbours and changes in the local ecology. This report describes about the investigation of wake wash developed from high speed marine craft in the towing tank. The data acquisition system and wave probe for wake wash measurement has been developed

Recurrence wave run up on a large volume semisubmersible

This paper addresses the problem of estimating the waves run up for a large semi-submersible production platform. Significant run-up evaluations on its squared-section columns were observed for the waves in operating design displacement. Some seed numbers generated JONSWAP waves in tank were used, and are generally regarded as a pure randomness in nature. Some identical sequences of relatively waves run up were found apart from one another for different seeds. This finding supports the recurrence of waves run up for the large semisubmersible platform

Study on zigzag maneuver characteristics of V-U very large crude oil (VLCC) tankers

The Department of Marine Technology at the Faculty of Mechanical Engineering, University Teknologi Malaysia has recently developed an Ship Maneuverability tool which intends to upgrade student's level understanding the application of fluid dynamic on interaction between hull, propeller, and rudder during maneuvering. This paper discusses zigzag maneuver for conventional Very Large Crude Oil (VLCC) ships with the same principal dimensions but different stern flame shape. 10/10 zigzag maneuver characteristics of U and V types of VLCC ships are investigated. Simulation results for U-type show a good agreement with the experimental data, but V-type not good agreement with experimental one. Further study on zigzag maneuver characteristics are required

Probability distribution of wave run up and dynamic response on a large volume semi-submersible

The wave run up under semi-submersible platform deck and the dynamic response are important design factors, and determine the expected minimum air gap in extreme design conditions. For a semi-submersible, the prediction of probabilities wave run up in harsh environments is a challenging task. This paper addresses the problem of expressing the probability density and cumulative distribution functions that utilize Weibull distribution to model estimates the waves run up for a large volume semi-submersible squared-section columns platform in two sea states. The two parameters Weibull distribution, namely shape parameter and scale parameter were considered. The analysis interpreted the measured data of 9 realizations with different seeds in the moored model experiments. The length of total measured data analyzed included approximately 9 times 250 waves for each sea state. The wave run up was found by model estimates using a Rayleigh distribution, and some waves run up were identical apart from one another for different seeds. Finally, by this model with a sequence return for two sea states the associated motions distribution for the large volume semi-submersible platform were numerically predicted

Ethical awareness amongst engineering students in Malaysian public universities

The area of ethics has received increased attention from the private and public sectors as well as academics over the past several decades. In the West, the highly publicized incidents at Enron and Arthur Anderson as well as WorldCom have brought the topic of ethics particularly business ethics to the public’s attention. There have been a multitude of scandals in the government, business and other areas of national life which includes the unethical conduct of top executives on Wall Street related to insider trading, the suspected misuse of research grants at Stanford University and a few other incidents captured by the media. In Malaysia, two general managers of the National Pilgrimage Board (LTH) had been charged in court for breach of trust by withholding information that could affect the decision not to invest RM400 million in foreign exchange activities (The New Straits Times, 15 February, 2003). The Malaysian government was also aware that one of the reasons for the failure of some government-linked companies was due to dishonest officers (The New Straits Times, 25 August, 2005)