(1) Bottom support of a vessel standing in a slip or at a dock. The keelblock has the form of a parallelepiped (0.8–2.0 m long, 0.2–0.5 m wide, and 0.8–1.6 m high) and consists of a steel or reinforced-concrete base and a pliable cushion (wood or rubber). Keelblocks with hydraulic hoisting, as well as keelblocks that are movable and collapsible under a load, are also used. Keelblocks spaced 1–2 m along a vessel’s length and at right angles to its keel form what is known as a keelway.
(2) A shaped support (boat skid or boat chock) for mounting a boat or launch on the deck of a vessel or on shore.