Open type air cavity

The open type air cavity comprises a ship body, a sealing cover structure is arranged on a ship body outer plate at the bottom of the ship body, a space formed by the sealing cover structure and the upper surface of the ship body outer plate is an air cavity, an opening is formed in the bottom of the air cavity, a bottom plate is arranged at the opening, a rotatable lock catch is arranged on the bottom plate, and the bottom plate is installed at the bottom of the air cavity through the lock catch. And vent holes are formed in the bottom plate. An air delivery pipe is arranged on the sealing cover structure, the tail end of the air delivery pipe is inserted into the air cavity, an anti-reflux device is arranged at the tail end of the air delivery pipe, a left valve and a right valve which can be opened and closed towards two sides are arranged at the end part of the anti-reflux device, and an air outlet is formed in the joint of the left valve and the right valve. The method has the advantages that the problem