[TorpX]

Only 1/3 of ships attacked actually sank.

US submarines were designed for a patrol lenght of 8 weeks, or 56 days. Three boats had patrols lasting 80 days or longer.

Average number of merchant sunk per war patrol: 0.8.

Good stuff here.

A question related to ST periscope radar : "The raised periscope was frequently used when on the surface to provide a higher "height-of-eye", and therefore greater detection range"

is it possible to do this in the game?

I don't know about the way ST radar is modeled, but with respect to visual searching, it does not make any difference in SH 4, if you raise the periscope when you're on the surface. In SHCE, you could indeed see farther when you raised the scope higher. Another dissappointment form Ubisoft.