Glad to see the ol' T class up there, they certainly 'out gunned' their US and German counterparts - the 1st group T class could fire a whopping spread of 10 torpedos if they wanted....
If im not mistaken there were really 3 major factors that let RN T class subs down;
1) Low surface speed; I dont think any of the WW2 RN subs could achieve more than 14 knots, The 1st group T-class Lost a few knots due to its poor Bow design. The 2nd and 3rd group had the bow redesigned to boost performace - however they also removed the 1st group's some what unreliable bow caps which caused some additional streamlining issues, (but still an improvment overall.)
2) The S-class used oval shaped pressure hulls to accomodate the the 6 internal fore tubes, oval is not a strong as circular - and had a detremental effect on max depth. Not completley sure but I think the T class suffered from the same problem.
3) External Tubes on the T-class were quite unreliable too.
Alot of T-class boats were lost in the Mediteranien, at 84 meters long (thats 3 meters shorter than a type IXD2 Uboat) - they were just too darn big to operate comfortably in those waters. I guess by 1941 there just wasn't enough prey for RN subs in the North sea and Atlantic, so they sent them in to the Med - At least the trip through the Gibaltar straights would have been rather pleasent for British sub crews.
Gotta Love the T-class though
