SWATH Structure: Navy Research and Development Applications

Abstract

The potential for enhanced seakeeping and increased operational effectiveness for certain missions has generated an interest by the U.S. Navy in small-waterplane-area twin-hull (SWATH) ships. Because of the novelty of these vessels, traditional design approaches cannot be used. Hence, the David Taylor Research Center has invested a considerable effort to develop suitable criteria for primary Ioadings, secondary Ioadings, and the structural response of these ships. This paper presents an approach for determining the maximum seaway Ioadings on SWATH ships and summarizes the results in simple design algorithms. Secondary slam Ioadings from model tests are presented. Algorithms for predicting the stress distributions on primary structure are also presented. Finally, some lightweight alternatives to conventional steel grillage secondary structure are presented. Overall, structural weight reductions are possible, with the biggest potential benefits arising from structural designs which resist secondary loads.