Hydrodynamic and Supportive Structure for Gated Ship Sterns: Amphibious Ship Stern Flap

摘要

Stem flaps have now been at sea for more than two decades on a variety of U.S. Navy (USN) and U.S. Coast Guard classes, including destroyers, cruisers, frigates, cutters, and patrol craft. Application of flaps to large-deck amphibious-type ships is a fairly recent extension of the technology. Ship performance improvements such as delivered power reduction and fuel savings, and maximum speed increases, have been proven during at-sea trials and are well documented (Cusanelli 2002). USN amphibious ships contain well decks, which are accessed through large folding stern gates. When open, the gates are supported by sizable structures, which are partially submerged and affixed to the transom. A new concept, the hydrodynamic and supportive structure for gated ship sterns, i.e., the amphibious stern flap, was developed and patented by the author (Cusanelli 2004a). This design combines a stern flap's hydrodynamic performance surface with the stern gate support structure. The Naval Surface Warfare Center, Carderock Division, has now designed and implemented this new type of integrated stern flap and gate support structure on several USN amphibious ship classes. USN ship design and research and development (R&D) programs have resulted in amphibious stern flaps being implemented as new construction items on two new Navy amphibious ship classes and one new subclass. The Fleet Readiness R&D Program has funded amphibious stern flap design, retrofit installations, and evaluation trials on two existing amphibious ships. Each amphibious stern flap design spiral, model-test series, optimization, full-scale implementation as well as performance benefits and fuel savings are discussed.