Influence of the main bulb's parameters of bulbous bow vessels on heave and pitch motions for head sea

PurposeThis paper addresses the influence of the main bulb's parameters of a containership on heave and pitch RAO for head waves.Design/methodology/approachTo obtain the RAO curves, these parameters are scattered over the design space through latin hypercube sampling (LHS), where different bulb designs are obtained using the free form deformation (FFD) technique. Linear RAO curves are calculated based on numerical software, split into various frequency intervals and assessed according to six evaluation parameters.FindingsThe findings show that maximum, minimum and average values of the RAO curve are useful indicators to study the RAO of a ship. Average values of the curve are reduced more than 6% for heave and over 24% for pitch with respect to a vessel with a conventional bulbous bow. The best designs concentrate the volume around the mid-lower part of the bulb, whilst the worst designs concentrate the bulb volume towards the upper part of the bulb.Originality/valueIn the literature, we get an overview of the influence of different bows on seakeeping. However, the influence of the bulb or large variations of the bow in a parametric way have not been studied yet. Since most of these parameters are derived from the RAO curve and ship motions, this paper focuses on studying the RAO curve for heave and ship motions of a bulbous bow containership. The objective is to minimize the RAO values of the curves so that most derived parameters reduce their values as well.