Current Projects chat and miscellany

i think you went a bit overboard with this post, MT
=))

So the >30bar external water pressure will deliver a high velocity jet into the ~1bar internal air pressure, since the shaft runs through a not "truly sealed" bearing between the internal machinery space and the external propeller.
http://www.navy.mil.za/newnavy/submarines/images/type_209_1400_mod_san.jpg