A catamaran type vessel for use in a wastewater facility for servicing submerged air diffusers is disclosed. The vessel has spaced apart pontoon having an A-frame spanning between the upper decks of the pontoon and connecting the pontoons. A hook connected to a winch is secured to a cross header above the space between the pontoons. The hook is lowered into water and lifts an air header, to which the air diffusers are connected. An air diffuser is then pulled on the pontoons and serviced. The vessel is then propelled to a position to service other air diffusers in the pontoon.