Cradle (drydock)

A cradle is the set of adjustable supports that carries a hull during docking, used in marine railways, ship lifts (synchrolifts), and some floating docks rather than the fixed keel-and-bilge blocks of a graving dock. The cradle conforms to the hull form so the docking load spreads over the bottom and bilge instead of concentrating, which suits small craft, fine-lined hulls, and repeated haul-outs. On a marine railway the cradle rolls down an inclined track into the water, the ship floats over it, and a winch hauls both up the slope. Cradle support points still follow the docking plan to land under bulkheads and frames and to clear shell appendages.