• Journal of the Korean Society of Marine Environment & Safety
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• v.6 no.1
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• pp.35-45
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• 2000

The slipway, which is one of stern construction, is necessary for stern trawler to let fishing implements, such as fishing net, otter board and warp, go out effectively. It may be doubtable whether there is any possibility for deckwetness to occur because the slipway is obliquely in contact with sea surface. The author discusses any possibility for deckwetness through slipway of stern trawler in wind and waves. A 350 G/T class, ocean-going stern trawler is adopted for the present study. The stem trawler is particularly assumed to drift with fishing implements hung down the slipway due to internal or external accident during fishing operation in real sea. The author considers two factors as possibility for deckwetness to occur through slipway. One is mooring effect of fishing implements hung down the slipway under wind pressure, and the other is relative ship motion in vertical direction in waves. Through the numerical calculation, the author clarifies that there is thin possibility for deckwetness to occur from above two points of view.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.40 no.1
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• pp.65-72
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• 2004

This paper deals with an experimental study on the dynamical characteristics of ship motion during trawling job on the real sea. The experiments were carried out on the small stern trawler, and roll and pitch motion of the ship according to the wave directions were simultaneously recorded by P/C in the same sea conditions. From these data, the statistical properties and power spectra were obtained, and then the analysis of ship motion in trwal job was made. As a result, it was found that the pitch motions in trwal job were displayed low amplitudes on the whole, but the rolling motions were displayed high amplitudes relatively, and very high value on the beam and quartering sea especially. Also, the trial ship has a high extinction coefficient in the roll motion, compared with the rule of stability, but when wave height takes 2.5m over, it can induce the safety of ship to scare occasionally. Therefore, a usefull countermeasure for the safety of ship has to be made adequately.

• Journal of Fisheries and Marine Sciences Education
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• v.15 no.1
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• pp.47-56
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• 2003

Recently with the conclusion of fisheries agreements between Korea and Japan, and between Korea and China, trawlers in korea must operate in smaller fishing ground than before. As a result of this, the possibilities of collisionin increases gradually between trawlers under operation in this area. Authors performed a series of experiments on board to give the information of collision avoiding action to navigators of trawlers. The obtained results are summerized as follows : 1. The greater the rudder angle, the smaller the value of T, but there is no big diffierence in K due to rudder angle. 2. The greatest distance is to be kept by the give way vessel to avoid collision when the crossing course angle is $70^{\circ}{\sim}90^{\circ}$. In this case the safety minimum approaching distance must be more than 5 times of her own length. 3. Risk of collision in crossing is more greater in obtuse situation than in acute one. 4. The navigator of the give way vessel must take an action to avoid collisions outside of the minimum safety approaching distance.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.29 no.4
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• pp.260-271
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• 1993

Due to depletion of fish resources as time goes on, the trawl fishing industries which have caught the demersal fish is confronting with financial difficulties. For the purpose of breaking these difficulties, trawlers are expanding the fishing targets to the midwater from bottom stock. The trawlers become to be able to detect the fish schools not only vertical but also horizontal direction by equipping the sonar system on board. Even though the operator locates the fish school by sonar, it is not easy to make a desirable catch of the fish school which is detected, for the reason of the maneuverring characteristics of trawler. For the purpose of enhancing the efficiency of a fish catch, the auther performed a series of on board experiments to investigate the maneuverablilites of midwater trawaler. The obtained results are summerized as follows: 1. The higher the RPM of main engine, the smaller the magnitude of turning circle. And it is smaller in the right than in the left turning 2. Towing speed varies irregularly under turning novenment. When the RPM of main engine being 560, 680 the angular velocities are 11.3deg/min, 22.5deg/min respectively. 3. The difference of new course distance between calculated by maneuverring indices and measured by experimental ship is high when altering course being large and towing speed low. 4. The faster the towing speed is, the shorter the new course distance becomes. When towing speed is same in right and left turning movement, the now course distance is shorter in case of right turning movement than in left. 5. It is considered to be convenient for a navigator to utilize the curves for altering course in order to steer the ship rapidly and accurately.