HULL FORM DESIGN STUDIES FOR MONOHULL COMBATANTS

In support of the power-limited design approach for monohull combatants, a series of hull form studies was undertaken with the objective of developing simplified algorithms for use in early design stage ship synthesis numerical models. Resistance, propulsion, and seakeeping performance were analyzed. Algorithms were generated for bare hull resistance, varying L/B and displacement with optimum prismatic, for the effect of bow and stern bulbs, and for the drag of appendages. Propulsion formulae were derived for twin screw conventional propulsion for large diameter, controllable-reversible pitch propellers, and counter-rotating propellers. For the specific case of the stern bulb hull, a single screw propulsive coefficient was determined. In the seakeeping area, equations were formulated to estimate secondary hull form parameters (given basic hull characteristics), for use in Bales equation for R, an established seakeeping measure of merit. Then, R was related to Operability Indices (OI) in various sea states and, thus, the overall Seakeeping Performance Index (SPI) for a specific "combat" set of motion criteria. The effects of fins and rudder roll stabilization were added. The result is an easy-to-use technique for determining seakeeping operability in early stage design. For the power-limited design approach, substantial benefits in propulsion and seakeeping can be obtained from a high L/B, optimum C(p), seakeeping hull form. Incorporation of a bow and stern bulb and single screw propulsor can further significantly improve powering with minimal impact on operability in a seaway.