First I'd ask your friend what are they going to paint it with. Is he is going to use Gel Coat, Automotive Paint, or something like Awl Grip? If he is using paint the boat will need to be primed first. Make sure the paint system - primer and topcoat match (use the same brand). You can use a high build primer to fill minor scratches and a lot of minor scratches will sand out of the get coat. When sanding always use a block if you are not using a power or air sander. Once primed the old color will not matter.

Gel coat can be sprayed over the old gel coat with a good sanding to give it bite.

Leaks can be a problem. If there are cracks paint will not fix cracks and they will crack the new paint and may cause it to peel. I'm a firm believer that you should grind / sand leaks and fix them with epoxy such as West System. Evercoat is good to use on the primer before the paint. Have fun it is a lot of work 95% of a paint job is the prep work.

www.TheManShed.net