Open-Water Resistance and Seakeeping Characteristics of Ships with Icebreaking Bows

Most research conducted on icebreaking ships has concentrated on their performance in ice fields. One area that has been neglected is the performance of such ships during their transit from their homeport to the ice field. The experimental research under-taken is intended to show how variation of icebreaking hull shape parameters will affect open-water powering and seakeeping performance. Based on a current U.S. Navy ice-capable ship hull form, a parent hull and four systematically varied hull forms were designed, fabricated, and tested in calm water and regular waves in the U.S. Naval Academy's Hydromechanics Laboratory 380-foot towing tank. Bow shape parameters considered to be of major importance for icebreaking--specifically, the waterline angle and the section flare angle at a point 10% of the waterline length aft of the forward perpendicular--were varied over ranges dictated by current 'good icebreaker practice.' Calm water resistance as well as pitch, heave, relative vertical motion, and added resistance due to waves in long crested head seas were determined on the basis of model tests using eight foot long models.