Abstract: Apparatus for mounting and dismounting a submerged propeller unit to and from the hull of a floating body from the outside thereof comprises a flange in the hull surrounding an opening therein and having passages therein, a flange on the propeller unit having fasteners at locations corresponding to the locations of the passages in the hull flange, a drive coupling member on the propeller unit, a plurality of guides on the propeller unit for guiding the coupling member into the hull opening and for positioning the propeller unit flange in proper relation to the hull flange as the propeller unit is raised into position, a lifting yoke carrying a plurality of lifting cables extending through watertight ways in the hull and adapted to be secured detachably to the propeller unit whereby the propeller unit flange may be raised to the level of the hull flange with the fasteners in the former in registry with the passages in the latter to facilitate securing the propeller unit flange to the hull flange.