Launching from a building dock is performed by flooding the dock to the depth required to float the ship. Careful planning and considerable expertise are required to launch a ship by sliding it into the water. Drag chains of predetermined weights are used to control the ship's entry into the water. Tugs are needed to control the ship after entry into the water. The ship is placed on the cradle and hauled out along a fixed inclined track.
Water is pumped out of the wing walls to raise the ship clear of the water line.
Dry dock operations. A.M. Best, 1975. McGraw-Hill Encyclopedia of Science and Technology.