• Title/Summary/Keyword: 끌줄의 장력

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On The Towing Speed and Warp Tension of the Stern Trawler in the Atlantic Coast of Africa (대서양 아프리카 연안 트로올의 예망속도와 끌줄의 장력에 관하여)

  • 김진건
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.13 no.2
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    • pp.21-26
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    • 1977
  • The author operated with a six seam trawl net by the stern trawler, No. 85 Parto, 499 GT, 2,200ps, in the Atlantic coast of Africa, from June, 1975 to October, 1977. In the term, towing speed and warp tension were determined, and trawling condition was observed. 1. The condition of trawling was good when the tension was less than 7.5ton. 2. 290 RPM, $13.5^{\circ}\;to\;13.8^{\circ}$ of pitch angle, and 3.5 to 4 knots of towing speed was considered as optimum for the trawler in the relation to the engine condition.

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A study on the static stability of the otter board in relation to the angle of attack (영각의 변화에 대한 전개판의 정적 안정성 연구)

  • Park, Chang-Doo;An, Heui-Chun
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.38 no.3
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    • pp.234-240
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    • 2002
  • The static stability of the otter board in relation to the angle of attack ($\alpha$) was studied analytically and experimentally from the moments of tensions and hydrodynamic force acting on it. Three flat plates of 0.5, 1.0, and 1.5 aspect ratios (λ) and four cambered plates of 5, 10, 15, and 20% camber ratios (CR) with the same aspect ratio (λ=1.5) were tested in a circulating water tank for measuring the hydrodynamic forces and moments relevant to the position of hydrodynamic center. And, center-of-pressure coefficients ($C_p$) and moment coefficients ($C_M$) of each plate as a function of the angle of attack were calculated for estimating the static stability from hydrodynamic forces. The obtained results are summarized as follows ; 1. When the angle of attack for otter board is changed from equilibrium for some reason, moments depending upon tensions of warp and sweep line always act in order to have the static stability, respectively. 2. Position of center-of-pressure of each flat plate moves from leading edge to center of plate with the increase of the angle of attack. It means that the moment of hydrodynamic force acting on flat plates also increases the static stability of plate. 3. With the increase of the angle of attack for cambered plates, the positions of center of-pressure move from trailing to leading edge, and then turn toward center of plate. As the camber ratios increase, the ranges of the angle of attack of the static un stability depending on moment of hydrodynamic force become wide.

On the motion characteristics of small trawler in trawling job and sailing (소형 트롤 어선의 예망과 항해중의 동요특성)

  • Kang, Il-Kwon;Kim, Hyung-Seok;Kim, Jung-Chang;Kim, Min-Seok;Jo, Hyo-Jae;Lee, Chun-Ki
    • Journal of the Korean Society of Fisheries and Ocean Technology
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    • v.40 no.4
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    • pp.311-318
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    • 2004
  • It is very important for the safe navigation and fishing operation to ensure the hull response of a fishing vessel in rough seas. This is an experimental study on the dynamical characteristics of ship's motion during operating job and sailing in the real sea. The experiments were carried out on the small stern trawler in operating job and sailing, and then the ship's roll and pitch motion were simultaneously recorded by P/C according to the wave directions. From these data, the statistical properties and power spectra were obtained and the analysis of ship's motions in the both case were made. The results obtained are summarized follows : (1) The amplitudes of pitch motion don't appear a big different between trawl job and sailing, but at bow seas, its in sailing have a tendency to increase more than in trawl job. The amplitudes of roll motion appear a bog different between trawl job and sailing, but at beam sea, that slightly decreasing tendency. (2) The peak period of pitch motion in trawl job and sailing change, but that of roll motion don't change according to the direction of waves. (3) The warp tention cause the motion of hull to be reduce, if the tention of each side have a ballance.