PURPOSE: To perform the hoisting work while a boat is directed perpendicularly to the longitudinal direction of a jib.

CONSTITUTION: A jib 3 is rotated and protruded above the water, and wire ropes 11, 12 are unwound by hoisting devices 13, 14 to lower hoisting accessories 10. Slings 16, 17 fitted to the hoisting accessories 10 are crossed in the width direction of the outside bottom section of a boat 15 directed perpendicularly to the jib 3 to hold the boat 15 at the front and rear positions. Slides 6, 7 are moved by hydraulic cylinders 8, 9 in the longitudinal direction of cross beams 4, 5, and the width size A between hoisting positions is adjusted in response to the shape and length of the boat 15. The wire ropes 11, 12 are wound by the hoisting devices 13, 14 to hoist the boat 15. The jib 3 is turned to the land side under this condition, and the boat 15 is lowered on a quay 1 for landing. The boat 15 is launched from the ground by opposite actions.