• Journal of the Korean Institute of Navigation
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• v.23 no.1
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• pp.1-13
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• 1999

Ship system can be divided into four sub-systems: hull, propeller, main engine and operation system which severely affect the characteristics of a ship. In determining ship speed in waves, two factors are considered the involuntary speed loss due to added resistance caused by wind and waves, and the voluntary speed loss by command of operation system to prevent severe ship motions. In this paper, the main function of four sub-system is analyzed for input/output relations and propulsive coefficient and a useful method to predict involuntary speed loss of a ship is presented. Two calculated examples for a high speed container ship and a passenger ship with single screw and diesel engine are given.

• Journal of Ocean Engineering and Technology
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• v.17 no.2
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• pp.67-71
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• 2003

Using motions (Maruo) and wave reflection (the author), speed loss due to wind (van Berlekom) and ITTC standard spectrum, and various effects of weather(:such as weather intensity, ship type, ship size and draught) on ship speed performance at sea were investigated. Further, a comparison of the relative effects of weather and hull roughness on speed loss was also studied for a VLCC.

• Journal of the Society of Naval Architects of Korea
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• v.57 no.3
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• pp.124-132
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• 2020

The purpose of this paper is to establish the basic procedure and method for selection of preferred anti-fouling paint considering economic analysis according to ship's speed loss based on ISO 19030 that has been published in 2016 to prescribe practical methods for measuring changes in ship specific hull and propeller performance. In this study, six (6) anti-fouling paint products have been assumed for alternatives with each target maximum average speed loss and carried out comparison of the alternatives and sensitivity analysis in assumed conditions for selection of the preferred alternative.

• Journal of the Korean Institute of Navigation
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• v.14 no.2
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• pp.15-31
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• 1990

Recently, there is a tendency to design the large full ships with lower-powered engine as the means for energy saving in ship's navigation at seas. Such a lower-powered ship is anticipated to show the different propulsive performance in rough seas, because the fluctuation of main engine load of lower powered ship is relatively large as compared with higher-powered ship is relatively large as compared with higher-powered ship. The fluctuation of propeller load is nonlinear at racing condition in waves. It is due to the variation of inflow velocity into propeller, the propeller immersion and the characteristics of engine governor. In this paper, the theoretical calculation of the nominal speed loss and the numerical simulation for the nonlinear load fluctuation of a model ship in rough seas are carried out. From the results of calculation, the following are discussed. (1) The ratio of nominal speed loss to the speed in still water. (2) The manoeuvring ability of ship and the operational ability of main engine in a seaway. (3) A method of the evaluation for the fluctuation of propeller torque and revolution on the engine characteristics plane. (4) The effect of engine governor characteristics on the propeller load fluctuation.

• Journal of the Korean Society of Marine Environment & Safety
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• v.2 no.1
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• pp.47-55
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• 1996

This paper intends to evaluate the seakeeping performance in consideration of nominal speed loss of ships in a seaway. Authors calculate the nominal speed loss in the Sea State of Beaufort Scale 6, 7 & 8 and obtain each response amplitude of ship;s motion by New Strip Method in consideration of them. This study presents some results of the seakeeping performance by the maximum dangerouseness of ships on each sea state.

• Journal of the Korean Institute of Navigation
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• v.25 no.4
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• pp.417-422
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• 2001

Every ship might be exposed to collision, grounding and/or various accidents. They may make some underwater holes on the hull. An underwater damage would cause her loss of buoyancy, trim, and inclination. Although a ship has some provisions against these accidents, if the circumstance is serious, she would be sunk or upsetted. Because of varieties of type of accidents, one could not prepare all of them. Many subdivision could prevent them, but it is difficult to realize it due to rising costs. This paper deals with physical phenomena of sinkage and an application on box type ship, and some results are earned as follows； 1. sinkage speed up to the level of the damage hole is increased proportionally, and is decreased proportionally after filling the level. 2. the curve of draft shows cup type of second order polynomial up to the damage hole level, and shows cap type of second order polynomial after filling the level. 3. if damage occurs beneath half of the draft, changes of head and displacement, and sinking speed follow almost straight lines. 4. by careful observation, sinkage speed could be predicted.

• Journal of the Society of Naval Architects of Korea
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• v.59 no.6
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• pp.345-354
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• 2022

It is easy for a ship passing through confined waters to be exposed in dangers of collisions and grounding due to different hydrodynamic responses. Since marine accidents can cause significant impacts on environments, global economy, and human lives, it is necessary to study the effect of shallow water on hydrodynamic performance of a ship. In this paper, the effect of water depth on resistance performance was investigated using CFD analysis as an initial study for improving navigational safety of a large container ship under confined waters. After a CFD set-up for deep water condition was validated and verified by comparing CFD analysis with model test results, CFD calculations according to ship speed and water depth were conducted. The features were investigated in terms of tendency and physical knowledge related to resistance performance. The increase of resistance due to shallow water effect was reviewed with empirical formula suggested from SWABE JIP. Speed loss due to shallow water effect was additionally reviewed from estimated delivered power according to ship speed and water depth.

• International Journal of Ocean System Engineering
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• v.2 no.3
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• pp.170-175
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• 2012

Currently, most logistics use containers. The construction of new port and high speed medium size container ship for the transportation of merchandise have become very important. The problem of ship stability is also important because of its direct influence on the loss of human life, ships, and merchandise. The stability of a container ship during its operation is not a large problem because it is well considered in the design process. However, the assessment of ship stability during container loading/unloading in port still depends on the expertise of experienced personnel. In this paper, a model based simulation system is introduced, which is able to assess ship stability during container loading/unloading, using ENVISION, a general purpose simulation system.

• Journal of Navigation and Port Research
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• v.38 no.6
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• pp.593-600
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• 2014

Information supporting system which is based on real-time prediction of currents to be applicable to the sea trial test of ship is developed. In the system, the spatial distribution of currents at specific time and the trends of variability of currents occurring at specific sites are also given as valuable information for sea trial test of ship. In addition, the system has a capability to connect with a GPS which provides information including speed loss of the ship caused by currents on the way of voyage. With information from the sea trial test, the system is also capable of delivering optimum time and pathways by considering calculated speed loss of ship at specific time and its pathway. Having information described as above, the real-time current prediction system supports and provides functions of not only running the test in an efficient way but also providing valuable information which is encouraged to be used during the test by installing at the ship.

• Journal of the military operations research society of Korea
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• v.25 no.1
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• pp.169-177
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• 1999

There is some limitations for ship to gather weather and sea state information. To make up for this weakness, land organizations can gather the wider variety of information, evaluate the navigational safety on a ship, and supply this information to the ship. In this study, the involuntary speed loss are calculated using the real-time information on weather and considering the increase of resistance induced by wave, and the navigational safety in a seaway is evaluated. The used model for computer simulation is Lpp 93m frigate class ship. The feasibility study is made of using simulation results in actual operation.