How does a submarine propeller shaft seal?

Question

How does a submarine propeller shaft seal?

Answer 1

The submarine shaft uses various bearings to support its weight and transfer propeller thrust to the hull.

It uses what are called shaft seals to reduce leakage inboard. They are similar to those used on pumps consisting of steel and carbon rings. In its simplest form a shaft seal is just a ring of fibre pressed against the shaft to r****d leakage. Any leakage from the seals is simply pumped overboard.

Details on shaft seal construction and performance are classified, but the fact they are used on submarines is not.

Answer 2

The first successful split seals were used on the atomic submarine main propeller shafts back in 1954. They proved to be as reliable as solid seals, but they were very expensive because of a lack of good technology for cutting the lapped faces or joining the O-ring seals.