Effects of Bilge Keels on the Rolling of Ships

Abstract

The effect of bilge keels on the rolling of a ship depends on many elements such as the area, the width, the aspect ratio, Reynolds' number, the draught of ship, the distance of bilge keel from the centre of gravity of ship, the height of centre of gravity of ship and the form of bilge. It was fouud that this effect is proportional to the nth power of mean velocity of the bilge keel, the index n being influenced by the width of bilge keel, the draught of ship and the distance of bilge keel from the centre of gravity of ship. Taking the above elements into consideration and analysing results of systematic experiments on the bilge keels with two dimensional ship models, a new approximate formula for calculating the decrement of angle of roll due to the bilge keels was obtained.