I think they are rated at 100 Kg each for a total of 200 Kg. At least those are the numbers that come to mind when I think back to my
Lipari. As for length, I think a 310 is just about the largest that I would suggest. We had one on order and then a Highfield 340 came available so, we grabbed it. Had it on our Lipari for a few months and it ended up being too long. It would fit, but you really have to muscle it around to get everything in its place and it would only fit with the
motor on the port side as the starboard side has that small shelf for the life raft molded into it. The folks who purchased our Lipari ended up with a Highfield 310 and it fits perfectly.