The big problem is your money is just disappearing in a depreciating boat, costing you more to maintain, run and keep up with fees.
As an alternative to buying property, it fails. In 10 years time, you will have spent a pile and have nowt worth much. A house will/should have earnt a tidy amount of equity in same time.
In your position, I'd be looking at buying somewhere up North and renting it out. Stills pays, even if still renting down here. Give it 5-10years, cash in equity for deposit for another place to rent. Rinse repeat.
Edit: re-reading that, it seems a bit condescending.
I guess, what I'm trying to say is, don't go down this route simply thinking it'll be a cheaper alternative to buying. it won't be. You should go down this route because you really want the living on a boat lifestyle, regardless of financial sense.