I don't know what it is about the raft, but it looks too small if you meant for the raft to be for humans. I think it could be the thickness of the sail that's throwing it off, but it could also be that it's not long enough. I googled for the lego figurine height but didn't find anything.
If you happen to own one, measure it. Then find a website on how to build a raft and find out measurements from that. It would look nicer if it was to scale.
Other than that, it's a cool concept that I might expand upon once I get the hang of 3dsmax.