An open-hulled outboard motor boat is not designed like a ship. Ships are designed and operated to have decks awash with no problems, they aren’t motor boats with open hulls ready to fill up with water like the motor boat experiment.
If methane eruptions were causing ships to go down, at least one of them would have escaped to tell the story.
As a merchant mariner, I’ve never heard of such an occurrance.
I’ve seen swamp gas seeps offshore ... Read even more