Abstract: A lifting apparatus includes a lift arm for carrying a platform or cradle and is pivotally attached to a base for movement between lowered and raised positions. A crank arm is pivotal with the base and a connector arm is pivotal with the lift arm. The crank arm and connector arm are pivotally connected to each other for rotation about a common pivot axis. Rotation of the crank arm by an actuator moves the crank arm and connector arm combination through a top dead center alignment a lowered over center alignment with the lift arm movable from the lowered position to the raised position during operating positions of the apparatus, and to a raised over center alignments with limited movement of the lift arm in the raised position for providing a locking position of the apparatus thus eliminating a need for typical additional locking mechanism.

Abstract: Devices, apparatus and systems for raising and lowering watercraft such as personal watercraft, jet skis, inflatables from transoms on boats, from bulkheads and from docks, and for raising and lowering other types of vessels. A single actuator such as a fluid operated cylinder and single piston can raise and lower a cradle that supports the personal watercraft. An crank bracket can be fixably attached to a crank shaft, and an arm which supports the cradle can be fixably attached to the crank shaft. The arm can be extendable to different lengths. The cradle can include a self-leveling carriage that uses rollers to roll on a curved surface of the cradle allowing the supported watercraft to remain in a substantially level position thereon. An adjustable swivel mount can also be used to lock the cradle to the arm in a fixed orientation.