Keel block

In marine terms, a keel block, is a concrete or dense wood cuboid that rests under a ship during a time of repair, construction, or in the event of a dock being drained. The block rests under the keel of a ship.^[1]

The purpose of a keel block is to prevent the ship from sitting directly on the ground and to prevent damage or instability that sitting on the ground may cause.^[2]