EFFECT OF BILGE KEEL ON ROLL OSCILLATION CHARACTERISTICS OF BANGLADESH INLAND PASSENGER VESSEL

Abstract

Vessel accident in Bangladesh inland water is a recurrent phenomenon and most of accidents taken place in stormy weather. If strong wind sustains for a long time, wind generated surface waves generate and it may roll a vessel beyond the limit. Bilge keel is the most prominent roll damper for a vessel. Currently there is no provision in statutory rules of Bangladesh for fitting bilge keel in inland vessels. This study has investigated the effect of bilge keel of different sizes on the rolling characteristics of a sample Bangladesh inland passenger vessel. Both the ship rolling in calm water (without wind and wave) and rolling due to combined action of wind and wave have been investigated. Wind velocity corresponding to Bangladesh River Danger Signal - III is considered for both wind and wave action. In inland waterways, waves are wind generated surface waves. Damping amplitude has been estimated by well-known Ikeda method. International Maritime Organization (IMO) has proposed a method to estimate roll damping coefficients from equivalent linear damping coefficients by simplified Ikeda method. The characteristics of roll motion (due to combined influence of wind and wave) namely standard deviation, zero crossing frequency and zero crossing period could be estimated from the estimated roll motion spectrum which is a function of the total moment spectrum of wind and wave.