[hyak107]

That is a big area to mess with using gel coat. Gel coat is really thin, to do it right you have to draw the corners of the of the scratches, which is time consuming. Since it's thin and also shrinks as it dries you normally have to apply several coats. I agree that Marine-Tex would be the best solution, it will probably outlast the the rest of the hull.

If you decide to go the gel coat route send me a PM and I can give you some pointers.