My concern wouldnt be whether they do the job but rather will they survive the shake rattle and roll on a boat. I had a quick google and i wasnt getting any useful info.
The only killer for lithium batteries is the heat management. Electric Car batteries are certainly a long way from just buy off the shelf stuff. ( think climate control). I personally would be weary of such large off the shelf lithium batteries. In a controlled environment, they are absolutely magic, on a boat? Not so sure.