I have been hosting a game for my friend and I since single player started. Mostly no problems until I built this boat. Actually, this is the second glitchy boat. I see the boat healthy, he sees the same boat as a collection of scrambled pieces. We are not sure where the problem is but I have been sailing this boat around for a while now and it hasn't sunk yet, so I can only assume that all the deck plates are in the right place.
When he logs in the boat looks wonky, but if he ports himself to a bed, then back to the boat sometimes it looks good and sometimes not. It has happened in a few different locations so it is probably not location specific. I have screen shots on my computer, but don't seem to be able to post them.