Salem

I have entered a mine with a boat lifted overhead, client crashed, after logging back boat was gone.

I believe this is a bug.
Mine wasnt pclaimed by me or anyone else.

It's most likely a bug, seems the boat had no where to land when you disconnected, so it disappeared. Happens to me when I'm carrying bears and I crash, sometimes the bear will just fly away a few tiles, other times it will have no where to land and disappear I guess it depends on how much space you have around you.