PROPELLERS
The Type IXC submarines is propelled by twin screws. They are solid three bladed propellers made from casr bronze having a specified tensile strength of 71,000 psi and an elongation of 20%. The propeller diameter as measured is 71.0 ins. The pitch or exact blade shape I do not know. The center of the propeller hubs are 46.4 ins. from the centerline, 49.1 ins. above the base line, and approximately 28.9 ft. forward of the stern. The approximate minimum distance from blade tip to ship's hull is 5.9 ins. Each propeller develops a thrust during surface operation of 33,000 lbs. at 500 rpm and when going ahead turns outboard.

The screws are secured to the shaft on a tapered surface with a standard navy submarine lockwasher and nut. The propeller cone is filled with tallow. A special rubber gasket is set between the propeller hub and the rubber coating on the shaft to provent leakage of sea water into the hollow shaft.