Sensitivity and trade-off analysis of wave making resistance and stability of small water plane area trimarans

Abstract

Recent concept ship designs have called for a vessel with the capability to lift and transport multiple medium displacement combatant boats, approximately 40 to 100 tons, at high speeds over thousands of nautical miles. One such design placed two small water plane area (SWATH) side hulls significantly aft of the center hull transom to facilitate a heavy duty hoist system. This thesis determines the optimal longitudinal and lateral positioning of small water plane area side hulls, and the number of and associated position of struts that would be used in a large displacement small water plane area trimaran design. The analysis explores eighteen different small water plane area side hull configurations to verify through a series of computational fluid dynamics calculations the total resistance and wake characteristics of the overall hull designs. A mathematical analysis of the wave making, frictional, and pressure resistance of each of the hull configurations will be developed using the Rankine Panel Method from the surface wave and flow analysis software package called SWAN2. Static stability and geometry data is generated for the concept design using computer aided design and RHINOMARINE hydrostatic analysis software. A systematic analysis of the results is conducted in order to determine the optimal side hull

separation, longitudinal position, and number of struts for best resistance and static stability which can then be used in a systems engineering process for further study of the feasibility of the use of a small waterplane area trimaran for a concept design.