My father recently dropped off an old windsurfer that he picked up at someone's yard sale. It's in good shape, as far as I can tell, but is missing the rear fin. I looked it over and can find no info printed on it at all with regards to make or model, except that it is a Bic. It's 12' long, and has two spots for the mast. Does anyone have any idea where I might even start looking to get specs on this thing? I think I can fabricate a fin for it, but I'd love to know what size I need to make it. I checked out Bic's website, but didn't see any vintage stuff.

Any help would be muchly appreciated.

It's an old Bic 250. Learnt to Windsurf in one of those back in the day. Heavy but a good shape to learn.