Direct stability assessment for towed ship in multi-directional irregular waves considering 3D dynamic towline tension during tow

2022 Fiscal Year Final Research Report

• Project/Area Number: 18K04592
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 24020:Marine engineering-related
• Research Institution: National Institute of Maritime, Port and Aviation Technology
• Principal Investigator: Kuroda Takako 国立研究開発法人海上・港湾・航空技術研究所, その他部局等, 研究員 (00415811)
• Co-Investigator(Kenkyū-buntansha): 原 正一 国立研究開発法人海上・港湾・航空技術研究所, その他部局等, 研究員 (60399524)
• Project Period (FY): 2018-04-01 – 2023-03-31
• Keywords: 曳航 / 動的索張力 / ランプドマス法 / 船体運動の時間領域計算法

Outline of Final Research Achievements

In order to estimate the dynamic towline tension actiong on a towing line during ship towing in waves, a method is presented to solve for the towing line tension by applying a three-dimensional lumpeds mass method with a formulated motion at the towing point of the towed ship.
Moreover, a time-domain simulation method for ship motions in short-crested irregular waves with memory effect is constracted to calculate the ship motion of the towed ship in irregular waves. its accuracy is confirmed by comparison with a model test.
As a method for evaluating stability of the towed ship based on the long-term occurrence probabilty was conducted. In accordance with the direct stability assessment in the second generation intact stability criteria, a process to indicate the long-term occurrence probabilty of phenomena caused by stability of towed ship was presented using a constracted time-domain simulation in irregular waves.

Free Research Field

船舶の耐航性能

Academic Significance and Societal Importance of the Research Achievements

本研究で示した船舶の曳航時の索張力の推定で曳航索の3次元的変形とその動的な影響を扱った3次元ランプドマス法で解く手法はこれまで行われておらず，曳航時の動的索張力，最大索張力の推定に有効な手段になると考える。
また，模型実験で裏付けされたメモリー影響を考慮した不規則波中時間領域計算法とその計算法を用いた長期発生確率による復原性評価の方法を示したことも，船舶の安全性に貢献できると考える。