Thanks for all the help and links so far! I just thought I'd post a little update.
So far I haven't been able to progress much on the actual building front, HOWEVER, I have met with some success on sourcing parts:
I managed to find a Chrystler 9.5hp outboard motor with a long rig, propellor still attached at the local scrapyard, which I bought for the aluminium price - nice! Actually it looks in such good condition I suspect that there's not much wrong with it and I'm going to try and get it running - in which case I'll try and build some kind of hybrid instead of pure electric.
I've managed to get, not one, but three motors! They come from lawnmovers and I don't know exactly how powerful they are (can't see any information printed on them apart from voltage. So now I have 2@24V and 1@12V electric motors. I have a friend with the equipment to test the rpm, watts etc so I'll post when I know more details and maybe someone can help me work out what kind of gearing I'll need?? They cost me 300SEK which is about Ã‚Â£25 for all three and he threw in some jumper leads and a nice plactic bucket to carry them in
On the way back from picking them up, we stopped by a yard sale and amongst all the pots and pans and crockery etc, there stood two large propellors about a foot accross. The asking price? 50SEK each - Ã‚Â£4! Now these are the kinds of prices I'm talking about when I say I'm on a "low budget..." I took them both, of course
My idea being that, since it's a largish heavyish "boat" I'm pushing, it would be good to have a big prop/low revs with the electric motor instead of the high revs/small prop that most seem to have - that should give me much more torque and pulling power.
I hope to start putting things together soon...