PITCH STABILIZATION FOR SURFACE COMBATANTS

Pitching is one of the most damaging motions for a ship, and is the ob vious choice after rolling for reduction to improve ship operability. Although SWATHs or bigger monohulls have greater operability, they are often costly. Therefore, some method of stabilizing pitch on existing combatant hulls should be found. Historical research has shown that d evices such as transom flaps and bow fins are ineffective or undesirab le, but canted rudders show some promise. Using criteria for ASW and m obility operations, a destroyer hull equipped with large canted rudder s using rudder pitch stabiliazation (RPS) was modeled on seakeeping ev aluation programs. Its motion and operability were compared with a bas eline hull (no RPS) as well as a SWATH and a larger Seakeeping Monohul l. RPS reduced pitch motions 30-40% and improved operability 6-11% ove r the baseline hull, making its seakeeping performance comparable to t he SWATH and Seakeeping Monohull. The use of high-lift devices can pro vide the same performance with reasonably sized rudders. We recommend a program to further develop pitch stabilization using high-lift cante d rudders, including development of high-lift foil technology and smal l-scale validation of the RPS concept.