This gear, for rapidly and simultaneously releasing the two ends of a lowered boat, was patented in 1898 by Lieut.-Col. G. S. A. Ranking and subsequently improved by Mr. Clark.

The boat is supported at both ends by chains, from a pair of levers suspended from the davits and having their free ends brought together over the middle of the boat, and there retained by a slip chain secured to the keel. When the central chain is released the two levers are free to turn and thus liberate the end chains, so that the boat is cast off. To give more rigidity to the arrangement and also to prevent the released levers from causing injury they are connected where they meet by a strong knuckle-joint which prevents any downward or sideway movement.