Drifting further off a contentious topic...

Sorry SS I think this is absolutely incorrect, submariners had a terrible record of correctly identifying ships, whether as targets for attacks or acting as intelligence gathering scouts.

Look at the massive over claims and mis-identification by virtually all skippers in all navies. It's doubtful that most were pathlogical liars so the only explanation for getting their observations wrong so often was wishful thinking combined with a consistant inability to get the identification correct.

HMS Ark Royal was "positively" identified and reported torpedoed several times before U-81 finally got her;

Prien believed he shot at a Renown in Scapa that was actually the tender HMS Pegasus. He missed;

Japanese captains constantly identified US warships as battleships and to U-Boat captains, every convoy escort was a "destroyer".

Post war records reveal that it was unusual when submarine commanders actually got an identification correct (Werner Hencke in U-515 is a notable and rare exception). In the Pacific, JANAC (Joint Army/Navy Assessment Committee) demonstrated how ineffecive American ship identification was when they assessed the results of the US unrestricted submarine campaign. Indeed, for some time US intelligence carried an extra Japanese aircraft carrier on the books as told in Blair's book Silent Victory that was the direct result of incorrect identification.

None of this is meant to be critical, rather given the special circumstances of WW2 submarine combat we should be surprised that they got it right on those occasions when they did.