Analysis of roll damping model scale data

Abstract

Having an accurate prediction of ship roll damping is crucial when analysing roll motions. In this paper, the simplified Ikeda method (SI-method) is compared with the original Ikeda method. The methods are compared using results from a database of roll decay tests carried out on modern merchant ships and a smaller set of predictions in which the original Ikeda method was used. It was found that most of the ships in the database had dimensions outside the limits of the SI-method. Thus, the SI-method showed poor agreement with model tests outside its limits but acceptable agreement for ships within limits. It was found that the deviations were caused by extrapolation errors of the wave-damping in the SI-method. Two ways to improve the accuracy of the SI-method were proposed based on regression, which gave about the same accuracy as the original Ikeda method.

Short-Term Prediction of Ship Roll Motion in Waves Based on Convolutional Neural Network

“…For the purpose of achieving precise prediction of ship roll motion, the key is to accurately determine the damping of roll motion in waves. According to Ikeda's theory [27], roll damping is mainly composed of friction damping, vortex damping, lift damping, wave damping and bilge keel damping. However, each part is coupled together, and it is difficult to determine each part separately in practice.…”

Implementation of the IMO Second Generation Intact Stability Guidelines

“…Moreover, an accurate prediction of µ e is difficult to obtain numerically, and even modern methods do not fully capture the physics [29]; however, the state-of-the-art remains in the application of CFD [30] or experimental results [31]. Simplified methods, such as "Ikeda" methods [32][33][34][35][36], to predict µ e could be too conservative, or alternatively an overpredicted µ e could have serious consequences on the attained vulnerability.…”