206 G. J. Wennagel 
Fig. 1. The ONR supercavitating hydrofoil boat 
the original hull. This addition increases forebody deadrise, so as to minimize wave impact 
loads on the hull, and forms a step on the hull bottom. Vertical tubes are installed within 
the boat and through the hull bottom aft of the step, to facilitate step ventilation. A second 
modification is an aluminum box aft of the transom of the basic boat which gives the craft a 
desired overall length and provides support for the tail hydrofoil and strut assembly. The 
third modification is an opening for the engine exhaust in the starboard side-skin near the 
aft end of the basic hull. Stainless steel sheet is used as a doubler around this cutout to 
provide strength over a region affected by the high temperatures of the exhaust. 
The basic hull skin is fabricated by stretch-forming two pieces of sheet which are 
joined together at the keel. Riveted construction is employed to attach hull and box exten- 
sion skins to ribs and longitudinal stiffeners. All the aluminum is 61S-T6 alloy. 
270 240 210 180 150 120 90 60 30 fe} 
LOA. 270 
s 
BASE LINE WL. 0. 
25 
--—__..__HIGH SPEED wt. b mal" 
WATER SPEED INDICATOR PITOT _ Ser 
12.95 
28.9 
POSITION | 
Fig. 2a. Side view of the ONR supercavitating hydrofoil boat (all dimensions in inches) 
