Well, the failure rate was most likely quite a bit higher. A lot of the early trouble was blamed on poor shooting and therefore counted as misses. There are Japanese witness stories in some of the JANAC reports from the post-war era that tell multiple times of torpedoes under-running ships. Sure, the US guys were "trained" for sonar approaches, and those probably missed a good 50% of the time, but they also received training on periscope and surface TBT approaches, and all good officers were "wizzes" at math...
- maybe... lol
But if you have some of the FotRSU versions, you will find the AddInModzPak in the "GameFolder / Extras", and you can go inside that AddInModzPak folder, and drag or copy the mods in there over to the MODS folder to check them out. There is
650_LotsaDudz = Frustrating level of duds encountered in FotRSU - All torpedoes
650_MoreDudz = Basically the middle ground of dud amoutns for FotRSU
650_OriginalFOTRS_Dudz = The amount of duds originally in FOTRS (or TMO v1.7)
... available for experimentation. You only use one at a time, and all three have slightly different settings for the duds and rates. I have used the "LotsaDudz" quite a bit, and it might be a bit much for some folks. I had one patrol trip while testing where I shot 23 torpedoes, and only one exploded where it should have, and of course, did NOT sink the ship... too many other vessels around, so I could not use the deck gun to finish them off... I brought the last torpedo back for testing - at least, that's my story about it... lol - The original FOTRS had the dud rate higher than Stock, so that is the "OriginalFOTRS" mod, and the "MoreDudz" is in between the two. It can be fun trying to recreate things the way they were then, but it is also extremely frustrating to be playing a game, and come back without having sunk a single ship - which actually happened more times than not.