The Rehabilitation Project Force developed out of a predecessor group, the Mud Box Brigade, which was formed aboard L. Ron Hubbard's private fleet in the late 1960s. The mud box is a small perforated screening box fitted to the suction pipe in the bilge of a ship, and is designed to catch larger solid waste before it can choke the pipeline and potentially damage the pump. The Mud Box Brigade was assigned to clean out the mud box as well as fuel lines, water hues, bilges and other parts of the fleet's ships.