
I can't even claim to have assumed that dismounting a boat onto claimed territory wouldn't work - although that would make fucking sense, at the very least - but in this instance I simply didn't have claim highlighting switched on, and didn't realise until I'd hopped off the boat and discovered I couldn't lift it.
Sigh... worth grinding 50k for Theft skill and risking death? Maybe... I had a nice anvil in there... :/