The game engine is sadly lacking in this department. It does not know what to do with the torpedoes, since a "gun" was used to simulate the torpedo. All AI guns are capable of firing at air, surface & submerged targets. I would not be surprised to see them also used against shore guns at some point. That is another reason why they were made short-range weapons in FotRSU. My main point is that there are at least several instances of submarines being shot at by destroyers with torpedoes. That one example was one of three that I can remember, but the only one I could find documentation on without spending 2 weeks going through the submarine
War Patrol Reports. The surface ship depth charge was the primary ASW weapon, airplanes probably 2nd, ship guns 3rd, etc... on down to probably 12th on the list for the torpedo (after potatoes even), and my guess would be that the several of their real life uses against submarines was mis-identification of the target due to the range, and therefore, an inappropriate weapon was utilized. Either that, or a torpedoman was at the ready, but no one was in the gun turret at the time...
