Hi melp64,
You can repair the gel coat without spraying. You will apply the gel coat with a roller, then sand, and then buff. Prepare the repair area by sanding, then wash with soap and water. Wipe with acetone just before applying the gel coat. Get a gallon of white finishing gel coat and tint to match. It will be difficult to match. Mix up enough for the repair. First color match then add the catalyst when you are happy with the color. Using a 9" foam roller, roll on the gel coat over the repair area. Observe the flow out. If it is not leveling then "tip" the wet coat with a foal brush to lay down the roller stipple. Let dry. Then sand with 120 grit. Be careful to not thin out the old the old gel coat around the edge of the repair area. Check that the applied gel coat has filled the repair area. If not wash, wipe with acetone and apply another coat of gel coat. Sand again and if surface is fair, then move through finer grit paper until you get to a 2000 grit. (Progress throug 220, 400,800, 1000, 1500, then 2000). The surface of the repair will become progressively smother. Now use rubbing compound the further smooth the finish. Follow up with buffing compound and then finish off with a good wax. A lot of work, but doable. Even if you sprayed the gel coat some amount of sanding and rubbing/buffing would be required to get a shine.
You can repair the gel coat without spraying. You will apply the gel coat with a roller, then sand, and then buff. Prepare the repair area by sanding, then wash with soap and water. Wipe with acetone just before applying the gel coat. Get a gallon of white finishing gel coat and tint to match. It will be difficult to match. Mix up enough for the repair. First color match then add the catalyst when you are happy with the color. Using a 9" foam roller, roll on the gel coat over the repair area. Observe the flow out. If it is not leveling then "tip" the wet coat with a foal brush to lay down the roller stipple. Let dry. Then sand with 120 grit. Be careful to not thin out the old the old gel coat around the edge of the repair area. Check that the applied gel coat has filled the repair area. If not wash, wipe with acetone and apply another coat of gel coat. Sand again and if surface is fair, then move through finer grit paper until you get to a 2000 grit. (Progress throug 220, 400,800, 1000, 1500, then 2000). The surface of the repair will become progressively smother. Now use rubbing compound the further smooth the finish. Follow up with buffing compound and then finish off with a good wax. A lot of work, but doable. Even if you sprayed the gel coat some amount of sanding and rubbing/buffing would be required to get a shine.