I am reading “Abandon ship!”, the US Navy saga of betrayal, lies and scapegoating connected to sinking of US Navy heavy cruiser USS Indianapolis in 1945. The Japanese submarine I-58 fired 6 (six) torpedoes at this ship after verifying that the ship was alone (no destroyer escort). Mochitsura Hashimoto, the submarine’s captain, desperately wanted a hit, to sink an American ship. But isn’t firing 6 torpedoes an overkill, especially when Japanese torpedo supplies and coming to a safe port were becoming more scarce? I am the furthest thing from a submarine commander, but I would fire maybe 2 torpedoes and see what happens. This large ship had no support vessels.
If one intends to kill as many of the crew as possible then even 6 torpedos can be little.
As far as I know, of the six torpedoes only two hit. The submarine commander seems to have had a realistic view of the capabilities of his torpedos.
Besides JPeelen’s info on this case we also may take into account possible duds which happened more often than one would imagine.
Also depending on the ship’s construction and possibe counter measures the damage caused by just one or two torpedos might not have been enough in particular when the ship kept steaming away after the hits.
I think that given the record Japanese submarines had in sinking capital ships under way and the very late date of the attack, 30 July 1945, firing six torpedoes wasn’t a bad idea. The sub commander may well have realized this would be his last chance to strike the enemy. Jack