Scratches are by far the most common damage to fiberglass boats. They can be caused by almost anything - branches on the riverbank to grocery carts in parking lots! Luckily, they are not serious problems. If they REALLY bother you, they can be repaired or minimized with ease.
Most of these little headaches do not penetrate through the gel-coat layer. Damage of this type can usually be sanded or buffed out.
Start by removing the wax and grease from the area with acetone.
Wet sand the area with 1000 grit wet/dry sandpaper. Use a pail of water and gently rub the area with wet sandpaper. Frequently re-wet the paper to remove the gel-coat dust (paste) from the work area.
The trickiest part of this step is NOT to sand through the gel-coat. Be a big chicken here. No heroes! If you sand through the gel-coat, you have just quadrupled the work you'll need to do.
Continue wet sanding with 1500 grit paper. This will produce a very shiny finish.
Wash the area with soap and water and follow up with a high-quality boat wax on a buffer.
For deeper damage that exposes fiberglass, you will need to do a little more work!
Of course, start out by removing wax and grease from the area with acetone.
Use a gouge to provide a uniform shape profile to the scratch.
Wipe the area down with acetone again to remove dust.
Fill the damaged area with a color-matched gel-coat paste. It pays to make up several small trial batches of the paste to MAKE SURE that the color matches! By the way, the color of this stuff changes as it dries - ask me how I know!
Leave the gel-coat paste a little thicker than the surrounding hull.
Once the repair has cured, wet sand with 1000 grit and polish. Back to the color thing...
If you have a small scratch that needs a little gel-coat to fill, you might want to consider simply buying a pre-assembled kit like this. It is a kit that contains 1 oz. of gel-coat, along with an assortment of tint packs. This makes it easy to be sure that you're getting gel-coat and compatible tints.
Go back to Cosmetic Repairs from Scratches