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.