It's not really strange that two torpedoes wouldn't do all that much to a
Yamato-class battleship. Digging out my copy of the "Anatomy of the Ship" book on her, I noticed a couple of important passages:
"The last test was carried out in 1939 on a full scale mockup of
Yamato which was attacked by 400 kg charges. The holding bulkhead did not remain watertight but was not split open."
"
Yamato's hull was divided into 1147 watertight compartments (WTC) which comprised 1065 below the armour deck (middle deck) and and 82 above."
"Her reserve buoyancy reached as much as 57,450 tons; this was 80 percent of her trial displacement... in the event of her bow or stern sections, other than the armoured citadel, being flooded, it was believed that she could maintain her stability under she listed to 20 deg, and that her trim capacity would enable her to function with her freeboard forward reduced to 4.5m - even if her fore part was completely destroyed and flooded."
"The flooding and pumping system was to fulfill the following requirements:
1. The resultant list and trim from the first torpedo hit should be reduced to under 4 deg list and 2.3m difference in draught for and after within five minutes of the damage control system going into action;
2. The resultant list and trim from the second torpedo hit should be controlled within thirty minutes, to the above-mentioned standard.
By flooding the opposite damage control tanks,
Yamato could also be heeled by 13.8 deg maximum, and another 4.5 deg list could be added by shifting fuel to the opposite fuel tanks."
It would seem the real problem is only using two torpedoes against a battleship designed to shrug off two simultaneous torpedo hits within 30 minutes and carry on like nothing happened.
