Abstract: Apparatus for abrasive blasting of the bottom of a ship in a drydock includes a blast head mounted on a vertically swinging boom on a vehicle. The blast head has freedom of movement about two pivot axes which are not parallel to each other. One of the pivot axes is coincident with the longitudinal axis of the boom. The center of gravity of the blast head is below the pivot axes when the blast opening normally faces upwardly. The boom and blast head are raised by double acting hydraulic cylinders which hold the blast head against the ship with a constant force. The blast head has a side edge which extends laterally at least to the side edge of the vehicle to facilitate blasting adjacent to obstacles under the hull. An overhung load adapter connects the blast wheel to its motor to minimize radial loads on the blast wheel motor. In the blast head, a stream of blasting material falling toward a main hopper is subjected to a transverse air stream which laterally deflects lighter particles into a debris channel.