• Title/Summary/Keyword: Longitudinal center of gravity (LCG)

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Empirical and Numerical Analyses of a Small Planing Ship Resistance using Longitudinal Center of Gravity Variations (경험식과 수치해석을 이용한 종방향 무게중심 변화에 따른 소형선박의 저항성능 변화에 관한 연구)

  • Michael;Jun-Taek Lim;Nam-Kyun Im;Kwang-Cheol Seo
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.29 no.7
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    • pp.971-979
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    • 2023
  • Small ships (<499 GT) constitute 46% of the existing ships, therefore, it can be concluded that they produce relatively high CO2 gas emissions. Operating in optimal trim conditions can reduce the resistance of the ship, which results in fewer greenhouse gases. An affordable way for trim optimization is to adjust the weight distribution to obtain an optimum longitudinal center of gravity (LCG). Therefore, in this study, the effect of LCG changes on the resistance of a small planing ship is studied using empirical and numerical analyses. The Savitsky method employing Maxsurf resistance and the STAR-CCM+ commercial computational fluid dynamics (CFD) software is used for the empirical and numerical analyses, respectively. Finally, the total resistance from the ship design process is compared to obtain the optimum LCG. To summarize, using numerical analysis, optimum LCG is achieved at the 46.2% length overall (LoA) at Froude Number 0.56, and 43.4% LoA at Froude Number 0.63, which provides a significant resistance reduction of 41.12 - 45.16% compared to the reference point at 29.2% LoA.

Estimation of Weight Parameters for Small Fishing Vessels in Accordance with Loading Conditions (소형 어선의 재화상태를 고려한 중량 정보 추정 기법)

  • Kim, Dong Jin;Yeo, Dong Jin
    • Journal of Navigation and Port Research
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    • v.43 no.1
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    • pp.16-22
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    • 2019
  • This study proposed estimation methods for weight and center of gravity of small fishing vessels. Weights loaded on small fishing vessels were divided into fixed weights such as crew, fishing gear, and variable weights such as fuel, fresh water, provision, bait, and fish. Based on statistical analyses with weight data of several small fishing vessels, weight, longitudinal center of gravity (LCG), vertical center of gravity (KG) of each item were represented as linear functions of vessel gross tonnage. In addition, weighting factors of variable weights were added on estimation formulas in accordance with vessel loading conditions, e.g. full load departure condition. Estimation methods were verified using actual small fishing vessel data.