A multi-rotor blower fan assembly for a cotton picker utilizes a plurality of separate fan enclosures each containing a fan for supplying an individual air flow to a picker unit of the picker, the fans being mounted on a common shaft for rotation therewith, with a unitary removable or openable cover or hood covering access openings of the fan enclosures. The tool comprises a tool housing and a hollow mandrel, the mandrel being situated in the housing. The result is a safe underwater motive device which will not accidentally become power actuated before the user is able to securely grasp and direct it, and which will not go to full speed except from a low speed to give the user a chance to stabilize himself in the water. A latch circuit temporarily latches data having the predetermined number of bits to the shift register in response to a block data latch signal.