Analysis on Rolling Damping of a Conventional Boat fitted with T-shaped Bilge Keels

Yam Ke San,Gordon Chiew,Sukanta Roy,Vincent Chieng Chen Lee,Chin Howe,Tzong-Hann Shieh

doi:10.1051/matecconf/201820202007

Abstract

This work presents a numerical study on the effect of T-shaped bilge keels on the roll damping of a conventional boat. A scaled boat model with the same dimensions as that of Irkal et al. [2] was fitted with two T-shaped bilge keels at the edges of the model. Computational Fluid Dynamics method was employed to simulate the roll decay motion of the boat. The motion of the boat is captured using a 6DOF model and the Overset grid approach. Comparison was performed on the damping characteristics of the conventional I-shaped and the T-shaped bilge keels. In addition, the impact of the aspect ratio of the keel bilges on the roll damping of the boat was evaluated. It was found that the bilge keel aspect ratio influences the damping coefficient non-linearly. Sufficiently large aspect ratio, i.e. an aspect ratio greater than 2, is necessary in order to obtain an effective damping on the peak angle.

Highlights

Stability is the ability of a boat vessel to return to its original position due to the presences of centre of buoyancy and vertical centre of gravity
The advancement of computational fluid dynamic (CFD) has enabled theoretical study to simulate the complex viscous flows around the hull which significantly enhances the accuracy of the prediction on the roll damping
This paper addresses the use of T-shaped keel bilges on roll damping of a common barge

Summary

Introduction

Stability is the ability of a boat vessel to return to its original position due to the presences of centre of buoyancy and vertical centre of gravity. Theoretical study on bilge keels designs is difficult owning to the significant viscous and eddies effects from the hull on the roll damping. The advancement of computational fluid dynamic (CFD) has enabled theoretical study to simulate the complex viscous flows around the hull which significantly enhances the accuracy of the prediction on the roll damping. A recent study by Irkal et al [2] on the decay rolling motion of a barge with bilge keels has shown that a good match between the numerical method prediction and their experimental result. A comparison study on the full numerical method of a boat with bilge keels against the traditional inviscid result [3] have shown that the inviscid approach significantly under-predicted the damping at high wave frequency range

Methods

Findings

Discussion

Conclusion