PURPOSE: To enable the draining of water accumulated in a racing boat easily and safely by utilizing vacuum generated with an ejector to suck the water accumulated in the racing boat into a catcher tank with the removal of a manual operation type water suction head from a holder.

CONSTITUTION: An air receiver tank 32 connected to an air receiver tank 32 is set on a pit device. An air master valve 50 is connected to the air receiver tank 32 through a main air valve 38 and a regulator 42 with a gauge. A catcher tank 52 is connected to the air master valve 50 through an ejector 44 and an air filter 48. Furthermore, a water suction tube 58 which has a manual operation type water suction head 60 with a changeover switch valve 40 arranged at the tip thereof is connected to the catcher tank 52. Then, the water suction head 6 is removed from the holder to switch the valve 40 for maintaining the inside of the catcher tank 52 reduced in pressure thereby enabling sucking of the water accumulated in the racing boat.