Comparison of Models of Cruiser Staying Power Against Torpedo Hits

In an earlier post I mentioned the SpringSharp measure of staying power for Derfflinger and Barham. In addition to the quantity of gunnery hits SpringSharp [1] gives a number of torpedo hits (presumably mean or median number to sink). Now I don't know what model underlies this number, but I do have another model where the probability of sinking is given for RN cruisers against the TPBE (thousand pound bomb equivalent) of torpedo hits. So if we set SpringSharp up to represent a particular RN cruiser we could compare the number of torpedo hits given by SpringSharp with that given by the model in [2].


Choosing Leander as the reference ship and setting up SpingSharp with its particulars we find the SS rates it at 1.2 torpedoes (presumably for 50% probability of sinking). Now looking up a 9000 ton full load cruiser on figure 4 of [2] we find that the TPBE for 50% chance of sinking is ~1.6, which is about ~1.3 equivalent 21" torpedo hits. This seems pretty good agreement, repeating the same for Edinburgh SpringSharp gives 1.9 and [2] gives ~2.2 TPBE which is ~1.8 equivalent 21" torpedo hits.


References
1. SpringSharp warship rough design software, http://www.springsharp.com/
2. Larham R., Historical Data in Modelling Warship Battle Damage Survival Probability, 2nd IMA Conference on Mathematics in Defence, October 2011, link to copy on Academia.edu