• Title, Summary, Keyword: Dragging Anchor

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A Study on the Limit of Anchor Dragging for Ship at Anchor( II ) (묘박 중인 선박의 주묘 한계에 관한 연구( II ))

  • Bae, Suk-Han;Jung, Yun-Chul;Kim, Se-Won;Yun, Jong-Hwui;Lee, Yun-Sok;Nguyen, Phung-Hung
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
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    • v.29 no.1
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    • pp.173-179
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    • 2005
  • In succession to previous study(A Study on the Limit of Anchor Dragging for Ship at Anchor sim I), the experiment of anchor dragging by ship handling simulator was performed to investigate the anchoring stability of ship at anchor in this study. The purpose of this experiment is to check the behavior charateristics of ship being dragged and the limit of anchor dragging for ship at anchor. A small tanker ship, which had been anchored in Jinhae Bay when the typhoon MAEMI passed on September 2003, was chosen as model ship for the experiment of anchor dragging and the result of experiment was confirmed to be very similar to the result of theoretical review and field report.

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Analyses of the Maximum Response of Cylinders-Connected Protector under Anchor Colliding and Dragging (앵커 충돌 및 끌림에 의한 원통연결 보호구조물의 최대 응답 해석)

  • Woo, Jin-Ho;Na, Won-Bae
    • Journal of Ocean Engineering and Technology
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    • v.24 no.5
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    • pp.81-87
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    • 2010
  • This study presents the results of collision and lift analyses of a cylinders-connected protector under stock anchor colliding and dragging. For the analyses, the terminal velocity of the stock anchor was obtained first, and, then, the velocity was used to calculate the falling distance of the stock anchor in air. In addition, two other falling distances were considered for purposes of comparison. From the finite element analyses, using ANSYS, the maximum responses obtained from the stock anchor colliding and dragging were obtained and compared for different collision distances (3, 5, and 8.83 m) and dragging angles (0, 30, 60, $90^{\circ}$). Then, the maximum displacements and stresses were discussed, along with the strength and dimensions of the protector. Finally, conclusions were made for the maximum responses.

Design of Rock-berm by Anchor Dragging Simulation using CEL Method (CEL기법을 이용한 앵커 끌림 시뮬레이션에 의한 Rock-berm 설계)

  • Shin, Mun-Beom;Park, Dong-Su;Seo, Young-kyo
    • Journal of Ocean Engineering and Technology
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    • v.31 no.6
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    • pp.397-404
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    • 2017
  • In this study, an anchor dragging simulation was performed using the CEL method to design a rock-berm, which is a protection method for submarine cables. In order to simulate an anchor drag, preliminary simulations were first performed to determine the initial anchor penetration depth, anchor drag velocity, drag angle, and distance between the anchor and rock-berm. Based on the preceding simulation results, a safe rock-berm design for protecting the submarine cables was simulated to calculate the anchor penetration depth by the anchor dragging. As a result, the penetration depth of the anchor was found to be shallower in a hard seabed, and the penetration depth was deeper in a soft seabed, the height of the rock-berm was determined according to the physical properties of the seabed.

Analysis on the Pattern of Dragging Anchor in Actual Ship (실선 계측에 의한 주묘패턴 분석에 관한 연구)

  • Jung, Chang-Hyun;Kong, Gil-Young;Bae, Byung-Deug;Lee, Yun-Sok
    • Journal of Navigation and Port Research
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    • v.33 no.8
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    • pp.505-511
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    • 2009
  • Vessels on anchoring are frequently dragged due to the increased area of wind pressure by enlargement of ship's size and sudden gust of winds in recent years. In the view point of the ship's navigators, the proper measurements corresponding to the dragging of anchor should be taken into account concerned about the time for the occurring of dragging by the external forces such as wind and wave, the pattern and speed of dragging and the possibility of collisions with any other vessels or obstacles. In this paper, it was examined the actual dragging anchor in T.S. HANBADA due to the wind and waves. From this case, it was found the critical external forces by which she was begun to dragged comparing the force by the wind, frictional resistance, drifting force and ship motion moment with the holding power. Also, through the analysis of the dragging pattern, it was known the alteration range of heading angle, swinging width and dragging speed etc.

The Development of the Anchor Dragging Risk Assessment Program (선박 주묘 위험성 판별 프로그램 개발에 관한 연구)

  • Kim, Joo-Sung;Park, Jun-Mo;Jung, Chang-Hyun
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.24 no.6
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    • pp.646-653
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    • 2018
  • Marine accidents caused by dragging anchors occur constantly due to enlargement of ships' size and unusual weather conditions. Nevertheless, vessel operators rely on their experience because the calculations of actual holding power and external forces are complex and inconvenient. The purpose of this study was to propose a program for the anchor dragging risk assessment in order to provide crew and VTSO with the information to determine easily the danger of dragging and take appropriate action. The input data in this program were composed of the ship's basic particulars, anchoring condition, and external environment etc. on calculating for the wind pressure, frictional force, drift force, and holding power. Three dragging anchor accidents were applied to the program's data input at the time of the day, then the result was assessed by 'warning', which was verified with a high confidence. As a result, the risk of dragging anchors can be predicted in advance through this program. In further studies, it is necessary to simplify the input data and improve user convenience through automatic input from various equipment.

A Study on the Holding Power Coefficient of AC-14 type and ASS type Anchor in Actual Ships (주묘 사례를 통한 AC-14형과 ASS형 앵커의 파주계수 비교에 관한 연구)

  • Jung, Chang-Hyun;Lee, Yun-Sok;Kim, Jong-Sung;Kong, Gil-Young
    • Journal of Navigation and Port Research
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    • v.35 no.8
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    • pp.613-618
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    • 2011
  • Vessels on anchoring are sometimes dragged due to the increased external forces. For preventing the dragging, it is required to enhance the holding power of the anchor. The holding power depends on the type and weight of the anchor and the seabed condition. Especially, the holding power of AC-14 type anchor is known to be 2~2.5 times bigger than that of ASS type anchor. However, these coefficients was determined nearly by the result of the model test, so there is a need to verify that by sea trial. Therefore actual dragging case was analyzed and then compared with the coefficients in use, it was found that the two of them are much alike.

Experimental Investigation on the Embedding Motion and Holding Power of Anchor According to Initial Position (앵커의 초기 투묘 상태에 따르는 파주운동과 파주력 특성에 대한 실험적 연구)

  • Lee, Sang-Min;Lee, Jin-A
    • Journal of Navigation and Port Research
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    • v.38 no.6
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    • pp.683-688
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    • 2014
  • The vessel should prevent dragging anchor against the external forces by utilizing the anchor and secure the stability of it. A fundamental understanding on the embedding motion and holding power of the anchor is necessary to perform the safe operating of anchor work. In this study, the embedding motion and holding power of the anchor according to an initial position in an experimental tank of 6m long in sand are tested by using two types of different anchor models(ASS and AC-14), which are generally applied to the commercial vessel nowadays. The anchor flukes seem to rotate and to be embedded into soil up to the maximum depth and maintaining a constant depth in case of the same direction and perpendicular to the towing direction, regardless of the form of an anchor. In case of the opposite direction to the towing direction, it is noted that the coefficient of holding power becomes smaller than the other initial positions.

A Study on the Anchoring Safety Assessment of E-Group Anchorage in Ulsan Port (울산항 E 집단정박지 묘박안전성 평가에 관한 연구)

  • Lee, Yun-Sok
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.20 no.2
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    • pp.172-178
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    • 2014
  • This study suggests the minimum critical external forces based on the assessment of anchoring safety to single anchor situation for representative 8 number of ships in E-group anchorage of Ulsan port. Assessment of anchoring safety is compared holding powers of anchor with external forces of wind, wave and current. Holding powers was reflected materials of seabed, equipment numbers regarding anchor and chain weight, also external forces acting on a hull was calculated considering projected wind area and wetted surface area to the full and ballast conditions respectively. The results of anchoring safety assessments to single anchor showed that the minimum criteria of dragging anchor is a little different from ship's type, size and loading conditions. Bulk carrier can be dragged over the 15m/s of winds and Tanker can be dragged over the 13m/s of winds in case of less than 2knots of currents speed.