Davit

A davit is any of various crane-like devices used on a ship for supporting, raising, and lowering equipment such as boats and anchors.
Davit systems are most often used to lower an emergency lifeboat to the embarkation level to be boarded. The lifeboat davit has falls (now made of wire, historically of manila rope) that are used to lower the lifeboat into the water. Davits can also be used as man-overboard safety devices to retrieve personnel from the water.
The maintaining and operation of davits is all under jurisdiction of the International Maritime Organization. The regulations are enforced by the country's own Coast Guard.
Development.
The development of the davit from its original "goose neck form" to the current devices advanced greatly when A.P. Schat patented a number of systems in 1926 that allowed the lifeboat to glide over obstructions on a ship's hull, known as the "Schat Skate". This was followed by a self-braking winch system that allowed the lifeboat to be lowered evenly. The standard became so common that shipyard specifications call for Schat-type davits which are available from various sources. Similar systems developed by Schat companies are used on offshore oil or gas rigs, being placed around the structure.
Development of the davit has also been in terms of material. Traditionally davits have been made in aluminium or steel but recent advances in composite material have led to the manufacture of davits in carbon fibre which has an excellent power to weight ratio. This means davits can be stowed away when not in use and the same davit used in multiple deck sockets fitted permanently on deck.
Lifeboat types.
Davits are designed to fit into deck spaces that the naval architects deemed necessary:
Release mechanisms.
There are 3 basic systems used to release the lifeboat from the davit. (Coast Guard Questions are for the Rottmer, On-Load releasing gear) 
Procedure.
For all lifeboats using a roller gravity davit and Rottmer releasing gear, this is the procedure:
During this procedure, if the lifeboat has air-cooled engines start it at the beginning. If it has a water-cooled engine start the engine after the lifeboat is in the water.