Nit, you won't be sinking the Yamato as a German. I've sunk my fair share of Queen Elisabeth battleships and they go down with just 3 torpedoes. Oh wait... I increased the damage by 20%... so... 4 torpedoes. If you hit a critical munitions magazine the effects will be dramatic. I've sunk a Heavy cruiser with just one torpedo under the engine room. The torpedo went a bit aft and struck the second turret area. I didn't expect that, I only hoped to disable it.
Most ships sink with just one magnetic torpedo if you aim it well. Note that ripping open a full cargo hold doesn't do **** in real life either. Always aim for the center of the ship. Worst case scenario, you'll disable their engines. The damage model is very realistic and the only problem is that the new KMFS ships don't show visible damage and don't start to visually sink until they are registered as sunk.
PS. I'm not exactly sure where the Water holds are on the ships or if they're even modelled. On modern ships they're situated at the stern. Flooding that area will only make the crew thirsty, not sink the ship
