People are going to die on this thing. It’s bad enough you can’t put out a class D fire on a ferry deck. You get a class D fire in the engineering space with a battery this big and you will get something that will burn for over a week at the bottom of Puget Sound.
No effective fire arresting technology exists for self oxidizing fires.
Sounds like a terrible way to die. People should probably make sure they have a good life insurance policy before they get on that thing.