This Kalfus type strut is made of O-1 tool steel with the cold rolled steel hexagon propeller shaft keyed & silver soldered to the strut piece. In the bottom of the strut, closer to the front, there is an angled water inlet. This water inlet & the B-8 grade Bearium metal bushings allowed this assembly to run indefinitely & never wear out. The .125 thick, O-1 steel rudder blade, was hardened & brought to a spring temper. This blade was machined a full wedge, front to back, before hardening. The leading edge was sharp enough to cut! The slotted bottom aluminum screw acted as a shear pin when the blade struck objects.
