PURPOSE: To shorten the stopping distance of a launching hull by installing a braking heavy weight such as drag chain or the like on the sea bottom of the end of a launching building berth, securing wires from the heavy weight to the stern of the hull, and restricting the launching velocity of the hull via a simple structure.

CONSTITUTION: Braking heavy weights 4, 4' such as drag chain, concrete block, etc.are installed on the sea bottom of the end of a launching building berth 1, and the ends of wires 5, 5' engaged at one ends with the heavy weights 4, 4', respectively are secured to the stern 2 of a launching hull 2. The intermediate portions 51, 51' of the wires 5, 5' are installed on the pedestal berth 7 engaged with the vicinity of the quaywall 6 of the building berth 1. When the hull 2 is launched on the sea 8, the wires 5, 5'are tensioned between the stern 21 of the hull and the heavy weights 4, 4' to thereby brake the hull via the friction between the heavy weights 4, 4' and the sea bottom 3.