A hulk is a ship that is afloat, but incapable of going to sea. Hulk may be used to describe a ship that has been launched but not completed, an abandoned wreck or shell, or to refer to a ship whose propulsion system is no longer maintained, or has been removed altogether. The word hulk also may be used as a verb: a ship is "hulked" to convert it to a hulk. The verb was also applied to crews of Royal Navy ships in dock, who were sent to the receiving ship for accommodation, or "hulked". Hulks have a variety of uses such as housing, prisons, salvage pontoons, gambling sites, naval training, or cargo storage.

A crane vessel, crane ship, crane barge, or floating crane is a ship with a crane specialized in lifting heavy loads, typically exceeding 1,500 t for modern ships. The largest crane vessels are used for offshore construction.