Owning your own home

Difficult to get a loan for - few lenders; difficult to get a mooring of any length in London; expensive mooring fees; depreciating asset with expensive maintenance costs; sea sickness....

Canal boats dont really depreciate.

Plastic boat - depreciates like car
Rare wooden boat - appreciates like antique
Canal boat - hold value if mantained

Mooring fees varie madly though. I lived in Henley-on-Thames for a few years (in a flat, not a boat), and the mooring fees there were astronomical and increased ten fold during the rowing regatta.