Barge Crane Low-poly 3D model

A crane barge is an offshore barge that has a sheer-legs crane or fully rotating crane. A sheer-legs crane can pick loads and luff but not swing. The sheer legs consist of an A-frame made up of two heavy, tubular members or trussed columns held back by heavy stays to the bow.

A sheer-legs barge is maneuvered by deck engines, tugs, or mounted outboard engine propellers. The crane barge positions its stern at the side of the material barge, picks the load, and then moves as necessary to set the load in exact position. Modern torque-converter deck engines and propellers with variable pitch allow a high degree of accuracy in positioning, on the order of 50 mm. One of the advantages of a sheer-legs crane barge over a fully revolving derrick barge is that the load is always picked over the stern end, hence preventing list from the swing of the crane.

The deck engines of a sheer-legs crane barge must be adequate to control the barge's motion in yaw, sway, and surge to a very close tolerance despite the state of the sea. The sheer-legs crane barges have a capacity of around 3000 tons.

A crane barge was successfully used to put jackets into pre-installed frames with a tolerance of only 50 mm.