Experimental investigation of wave-induced motions of an obliquely moving ship

The lateral drift appears due to the effects of wind forces and/or wave drifting forces for a ship sailing in actual sea. The effects of wind forces and / or wave drifting forces in views of lateral drift for ship moving with certain forward speed have not been studied previously. Therefore, it is important to investigate experimentally the influence of the lateral drift to ship seakeeping performance. In this paper experimental results for the ship motions and drift forces on a container ship SR108 obliquely moving in waves are presented. An outline of the model test are also presented in this paper. It is shown that sway, yaw and roll motions are significantly occured even in head waves. In general it is also found that the ship motions and drift forces are influenced mostly by hull drift motion

Design verification of heat exchanger for ballast water treatment

Using waste heat from ship's engines is one of the methods considered for heat treatment of ballast water. For such a system harvesting the engine exhaust heat, a heat exchanger will be vital. Design optimisation of a heater employing exhaust gases of the engine as utility fluid and ballast sea water as the process fluid was achieved using Lagrangian methods, keeping the annual cost as the objective function. Costs for installation, maintenance as also costs for the utility and process fluids were considered. Heat balance data, specific fuel consumption values from a typical operational ship and current fuel costs were considered for the design. The thermodynamic and geometric designs were worked out using computer based software for comparing the designs. Costs were also computed using a different approach for all the designs. Since the amount of heat transferred was specified and the application was limited to a single process, direct cost method was used for the computation. The objective function values obtained from Lagrangian equations were compared with the values obtained from direct cost computations. From the optimal designs, choice was justified based on annual cost, optimum exit temperature of shell side fluid and optimum mass flow of tube side flui

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

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

Evaluation of service performances of Liquefied Natural Gas Carriers in actual seas

Ship performance in actual seas represents the true performance of the ship throughout the service life and is affected by the combination of various conditions i.e. environments, loading patterns and ship conditions. Environmental conditions of wind, wave, swell and ocean current are chaotic and stochastic in nature. Loading condition may vary in draft, trim and motions in each voyage. Ship condition is susceptible to hull and propeller fouled over years. This paper provides insight into the service performance of Liquefied Natural Gas Carriers (LNGC) in actual seas derived from post-mortem on years of voyage’s noon report collections. Evaluation method of service performance will be proposed and benefits that can be gained from such analysis will be discussed

Review of course keeping control system for unmanned surface vehicle

This paper presents a review of research work done on various aspects of control system approaches of unmanned surface vehicle (USV) in order to improve the course keeping performance. Various methods have been used to produce a course keeping control system for manoeuvring system of USV. However, the review reveals that the adaptive backstepping control system is a powerful tool for the design of controllers for nonlinear systems or transformable to form a tight feedback parameter. It is very suitable for the automated control system of USV in relative motion that involves the disturbances from waves and wind. Fuzzy logic control also had been suggested as an alternative approach for complex systems with uncertain dynamics and those with nonlinearities. This method does not rely on the mathematical models, but the heuristic approach. Further studies may be conducted to combine the control method approach mentioned above to develop a real time system with robust control laws to the motions of a USV in waves, usually at a specific speed, including station keeping or heading in sinusoidal and irregular waves

Drag analysis of three rudder-shaped like bodies

This paper presents an investigation of Rudder Shaped-Like (RSL) hull configurations with low-drag characteristic using the resistance model tests and numerical analysis. The new design of the floating platform using three hulls with a self-manoeuvring system as Unmanned Surface Vehicle (USV) and capable of collecting the same data as a hydrography boat is needed. This platform was designed with three hulls placed in a triangle position in the form of rudder shape and vertically placed as a slender body shape using National Advisory Committee for Aeronautics (NACA) 0012 profile. This provides the low-drag characteristic to USV. The results from the experimental and numerical analysis revealed that a larger configuration distance between three hulls leads to a reduction in resistance of the same speed. This result may help to accomplish the required concept design related to low-drag and minimum power operation