Abstract: A rigid, arched disk (10) is placed convex side down in a cloth skirt (12). The cloth skirt includes an annular bottom portion (20) which covers the convex surface of the disk and a curved upper portion (22) which ends in an annular reinforced upper edge (24). The annular upper edge (24) is smaller in diameter than the outer periphery of the arched disk (10). A zipper (28) in the skirt enables the upper annular edge to be expanded to receive the arched disk. An inflatable tube (14) is inserted into the skirt resting on a concave surface of the disk adjacent its periphery. The inflatable tube is inflated with a sufficient pressure to lock the tube, the skirt, and the disk against moving relative to each other. When the assembly sits still in the water, water flows into the concave surface of the disk through an aperture (16). When pulled by a tow rope connected with a pull loop (30), the convex surface of the disk lifts the device up out of the water, allowing water to drain through the aperture.

Abstract: A tubular member (A) defines an internal bore (10) in which an inertia assembly (B) for providing a selected inertial force is disposed. The inertia assembly includes a spring (20) and a slidable member (22). An elongated, flexible cable (C) extends from the slidable member, through the tubular member internal passage, and defines a contractible loop externally of the tubular member. Under manual urging of a handle (36) which is operatively connected with a sleeve (34), the sleeve urges the slidable member longitudinally along the tubular member internal passage extending the spring. The slidable member cams a blocking member (70) outward to allow the slidable member to move therepast. After the slidable member is moved toward the tubular member second end past the blocking member, the blocking member blocks the slidable member against return sliding movement. A trigger (78) selectively withdraws the blocking member to allow the slidable member to undergo return sliding movement rapidly contracting the cable.