Just a quick Google search for 'ferry fire' lists many incidents over the last few years, and the top few were all closer to home than you may think including one out of a place we all know and love - Kiel - and thats in the 21st century with wonderful fire-retardants and the like. I imagine 70 years ago the regulations were slightly less strict than today and it wouldn't have taken much for an engineer (
other jobs may also be culpable) to drop an oily rag against a pipe, a dropped cigarette or even cooking apparatus to start a fire in rough seas.
So the idea is conceivable, but SH3 may just make it happen once too often.
