Abstract: A system is disclosed to reduce the impact shock associated with operating a planing boat at high speeds. The system, called "LocalFlex," comprises an outer bottom placed under the inner bottom of the boat. The outer bottom is spaced a distance from the inner bottom. The outer bottom comprises two plates. Each plate is connected to the inner bottom along or near the keel, and along or near the chine. Along the keel, each plate of the outer bottom is attached to one or more hinges or pins rigidly suspended from or below the keel of the inner bottom. At or near the chine, each plate is connected to the boat by one or more springs. The elastic modulus of the plates and that of the springs are selected so that the outer bottom deforms under the pressure spike of an impact in a whip-like flexure that smoothly directs the pressure spike past the chine. After the spike passes the chine, the pressure diminishes and makes no further significant contribution to impact slamming.

Abstract: A propeller assembly for mounting on the drive shaft of a motorized water vehicle. The propeller consists of a central hub having a hollow body of circular cross-sectional shape through which exhaust gas from the motor can flow. Integrally formed with the hub are a number of arcuate blades. Each blade has a generally fish-shaped axial cross-sectional shape. In particular, from the leading edge of the blade, the cross-sectional shape increases in thickness until reaching a local maximum at a point near the midchord of the blade and thereafter decreases in thickness until reaching a local minimum. The blade thereafter again increases in thickness along concave surfaces until terminating in a concave trailing edge. The trailing edge of the blades are in communication with the exhaust gas flowing through the hub.

Abstract: A "fish-shaped" hydrofoil section and in particular, a hydrofoil section having a body of cross-sectional area increasing in thickness from the leading edge to a point near the midchord of the hydrofoil section. The thickness of the body then decreasing some amount to a local minimum, and thereafter increasing along concave surfaces in a "fishtail" flare to a local maximum thickness at the trailing edge. A low pressure area develops behind the trailing edge of the "fishtail" flare and is ventilated with gas at a pressure greater than that of the developed low pressure area. The cross-sectional shape of the hydrofoil section can be symmetrical or cambered.

Abstract: A multi-bladed marine propeller designed for efficient operation in intermediate, partially cavitating flow regions between fully cavitating flow and noncavitating flow. Each of the blades has a radially inner subcavitating section and an outer section which is configured to have a higher angle of attack and tapered trailing and leading edges so that it supercavitates at high speeds either with or without ventilation and subcavitates at low speeds. Various other features of each blade include different length chords on the pressure and suction sides of the outer section and an inclined trailing surface area extending between the chord ends for improved off design, design point, and astern operation. A minimized transition area is included between the inner and outer sections, and narrow chord lengths are provided in the tip area to minimize and balance overall tip section drag.