It looks like I may be spending a couple of years living on my boat as from this summer, so - "An allowance for domestic use will be permitted". I would hazard a guess that my heating useage will be about 90% of fuel used. Somehow, I can't see a goverment making allowances of much more than say 10%-20% thus I will be getting taxed unfairly. I guess I will just have to go and have seperate tanks fitted !!