Nutty said:Top stop
I think D-L's reference to S and T's are the boats constructed during WW11 not the SSN type. Certainly on Truncheon we had the Magnetic Compass in the fin viewed via a dim, dirty and damp periscope system not near easy eye level which was difficult to steer by.
SINS etc were an item of the future for us.
OOP`s sorry I keep thinking I`m old.