The Influence of a Keel Bulb on the Hydrodynamic Performance of a Sailing Yacht Model

Abstract

The scope of this work has been to investigate the overall performance of a sailing yacht with a keel-bulb configuration. Experiments were carried out at the Laboratory of Ship and Matrine Hydrodynamics (LSMH) of the National Technical University of Athens (NTUA). A 1⁄4 scaled model of a 50-ft modern sailing yacht has been tested. Experimental results referring to the drag, the side force, the dynamic C.G. rise and the dynamic trim, are presented. The performance of the model in calm water was evaluated, both with and without the bulb attached to the keel for a grid of leeway angles and three model speeds. In addition, the free surface elevation has been measured at various distances from the hull and characteristic wave cuts are presented.