Numerical and experimental investigation of the effect of an inverted bow on the hydrodynamic performance of Navy combatant hull forms

Abstract

In this paper we investigate the resistance and seakeeping effects of an inverted bow by comparing the motions of an existing combatant hull, the Oliver Hazard Perry class frigate (FFG-7), with a modified version of the same hull with an inverted bow. The bow of the FFG-7 was redesigned by developing a set of basic curves that define the parametric surface of the new shape. Two 1/80th scale models were built, one of the original and one of the inverted bow frigate, with the same material, machining and finishing standards. Model tests were conducted in the United States Naval Academy Hydromechanics Laboratory for resistance in calm water and seakeeping in both regular waves and irregular head seas. The differences between the FFG-7 and the inverted bow responses are characterized in terms of pitch, heave, and vertical accelerations. A numerical verification and experimental validation of the seakeeping code Aegir was conducted using the inverted bow.