A davit is a type of metal structure, found most commonly on boats, with an arm that extends over the side of the craft so that it can lower items to the deck below. It can also be used in building construction. The term may also be used to describe a metal arm with a winch that mechanically raises and lowers items from one place to another.
Davits are most commonly used to move boats, though they can also lift cargo and anchors. They can also be used to lower a maintenance trapeze over the side of the boat. There are four common types of davit: mechanical quadrantal, single pivot gravity, gravity roller track, and free fall.
Single pivot gravity davits are one of the most popular types of davit. They tend to have a simple design and few parts, which makes them easier to adapt to different tasks. This type can also accommodate a wide array of deck types and sizes.
The gravity roller track davit is most frequently used with promenade decks, which typically consist of port-to-stern open walkways on both sides of the ship. They usually have two arms and tend to be lighter than other kinds of davits.
Mechanical quadrantals are the oldest style of davit. They were usually cranked by hand and depended on pulleys and balance to function properly. Though they are no longer the dominant type of davit, mechanical quadrantals are still used in modern times.
Free fall davits are among the newest designs. They have fast-acting mechanisms that allow items to fall into the water while staying clear of the side of the boat. These are used almost exclusively to drop lifeboats into the water. A similar purpose is served by ramps which extend from the end of the boat and may occasionally replace davits on a craft
There are several other varieties of more specialized davits. The stored power style has an independent energy source which can be useful in areas where power outages commonly occur. A-frame styles have a metal structure that extends around the sides of the item being moved. Cantilever davits have a simple, boxy shape which extends from the deck of the ship and over the dock. The overhead style looks similar to the cantilever, but works via a more complex telescopic mechanism. There are also crane davits which have an extended reach that works well with larger loads and craft.