Abstract: A high-speed, ultrastable, wind propelled watercraft employs an airfoil for propulsion and buoyant hydrofoils for support. A buoyant keel/rudder is rotatably mounted to a boom which horizontally projects from near the base of the airfoil. Both the airfoil and the keel/rudder steering axis are inclined from the vertical substantially in parallel. The particular orientation, freedom of movement, and shapes of the various foil, support and control surfaces enhances the maneuverability of the craft and allows the craft to be sailed at most pointing angles.

Abstract: To hold a plug and socket together, a three-prong plug including two active prongs and a grounding prong is provided with an additional locking member which is recessed into the grounding prong. The grounding prong on the male portion of the plug has a V-shaped or U-shaped cross-section with the two sides of the electrical prong coming together with a ramp configuration at the outer end of the prong. An elongated locking member is mounted for longitudinal movement within the cross-sectional configuration of the grounding prong, with the outer end of the locking member engaging the ramp when the locking member reaches its extreme outer position to force the locking member transversely out of the recess within the U-shaped or V-shaped configuration of the third prong and into engagement with a portion of the mating female prong.