Abstract: A device mountable to the anticavitation plate of a propeller drive unit for a watercraft. The device includes a mounting member and a pivotable plate member mounted thereto. The mounting and plate members are both located below the water line when in operation, with the plate movable between a first position intersecting the backwash from the propeller driving unit and a second position wherein the plate is held parallel to the anticavitation plate and clear of the backwash. A locking assembly interconnects the plate and mounting member for locking the plate in either position. A control cable is attached to the locking assembly and extends therefrom into the watercraft.