I used an old windsurfer board for a couple of years when I first started SUP'ing because there was nothing else available back then.
My fiend Mike has been using it now until he can afford to buy something himself and in the meantime he's paddling and having fun.
Last week I dug out another old windsurfer board that I had under the house for him to try.
It's an old Cobra board (it's about 12'x29") and here's a few pics from last week when we gave it a test paddle.. It worked great..

DJ