Scuttlebutt is they celebrated the beginning of SH4 with a party (rum was involved) and made the quality control guy walk the plank, then forgot to hire a new one after they sobered up.
Made a new test mission with one of each type running around and around a 10 X 15 mile racetrack (no, I don't know how many furlongs that is) in rough seas. Reset all the damage points to 0.3, so 20 points per minute loss when below critical depth. Changed that NAKA to 400 hit points, reset critical ("crash") depth to 4 for CL, 4.5 for CA, 5 for CV and BB, 6 for Yamato. Had to convert into real money to visualize how much those are, so light cruisers sink 13.2 feet, heavies 14.85, BB and CV 16.5, Yamato 19.8. At this point it's mostly guesses based on TLAR engineering (T-L-A-R = That Looks About Right), difficult to tell how much freeboard has been lost while testing with no plimsoll marks. The random element is still there of course, one fish explodes under a turret and sets off a huge secondary in a magazine so down she goes, next one yields the minimum EF and minimum radius blast and the same ship settles 4 or 5 feet, not enough to trigger the new gadget. A Yamato gets four fish with holes big enough to stuff Rosie O'Donnell into, cruises around the circle (about 4 hours per circuit) and gets one more fish, sinks about 10 minutes later. TLAR, 10 minutes would be 200 hit points, out of 1500 would be 1300 divided by 5 Mark 14 hits, about 260 HP per torpedo. Obviously sugar boat drivers with their Mark 10s will need more fish, and of course the random element and the sea state could mean anywhere from 1 to 10 fish. Again I removed Webster's improved torpedo mod and am testing with the stock SH4 mark 14s.