is journalled in the power leg casing 70 which includes a flange 72 having a part spherical surface seating inside the head and extending through a slot therein the slot has parallel sides and semi circular ends and extends at least from the position vertically below the centre of the head around the head that is rearwardly and upwardly being symmetrical of a vertical plane containing the axis of shaft 24 the ends of the slot are indicated by references 74 76 fig3 flange 72 has a part spherical concave upper surface 78 fig2 and 3 lying normally of the shaft 64 axis and is trapped between slipper blocks 80 and the head interior and the blocks are bolted in place at 82 and bearing shims 84 which might be belleville sping washers are located between the slippers and the said surface 78 fig2 the flange is thus held against the head but permitted to turn about the centre to take the power leg along the slot a seal ring 85 is located at the periphery of the slot and may be of elastomeric material the angle of inclination of the power leg to the transom is controlled e g by a ram 86 fig1 coupled between the leg and the transom and associated with valve means holding fluid pressure in the ram to control its effective length and in the event of the leg hitting an underwater obstacle this may apply a load sufficient to overcome the valve and allow the ram to extend and the leg to pivot along the slot alternatively spring loaded catches may be employed to the.