Keel block

A keel block is one of a line of blocks on a dry-dock or slipway floor on which a vessel’s keel rests when the dock is pumped down or the ship is hauled out. The blocks take the hull’s docking load through the keel, with bilge blocks and side shores carrying the rest of the weight and holding the hull upright. Block height, spacing, and crushing strength are set from the docking plan and the keel reaction per meter, since concentrated loads can run to hundreds of tonnes per block on large ships. Timber, concrete, or steel-and-timber composite blocks are used. The block layout must match the ship’s keel profile and avoid sea-chest, transducer, and propeller-shaft openings.