JHSS Baseline Shaft and Strut (BSS) Model 5653-3 Added Resistance and Powering and Ship Motions, Sea State 6 Random Waves and Regular Waves

Abstract : Resistance and powering tests were conducted on Model 5653-3 in calm water, in sea state 6 (SS6) random waves, and in regular waves. Model 5653-3 is representative of the Joint High Speed Sealift (JHSS) conventional Baseline Shaft and Strut (BSS) hull. The objectives/purposes for resistance and powering in waves experiments and results were twofold; for JHSS indicative hull design support and for US Navy design and evaluation tool validation. Powering tests in waves determined the additional power required by the JHSS indicative hull design to maintain speed in SS6 relative to calm water conditions. SS6 analysis indicates that sizing of the propulsion plant in a sealift-type hull for 39 knots in calm water should assure that sufficient power is available for achieving 36 knots in SS6. The 39-knot speed of interest will not be attainable in SS6 for the indicative JHSS baseline design with the total installed power envisioned. Qualitative observations indicate that the long, slender sealift design, when running in SS6, would likely experience only mild pitching and no occurrences of slamming at the bow or stern regions, despite the heavy sea state. The motions of the model were not significantly influenced by propulsion thrust or the ability to surge longitudinally. The model tests conducted in regular waves conditions were used to determine the critical wavelengths that resulted in the largest increased resistance in regular waves. Subsequent testing at these critical wavelengths provides a large matrix of resistance and powering data for comparisons to various numeric prediction tools. In addition, roll decay tests, with and without bilge keels, were conducted.