Simple Do-It-Yourself Gel Coat Repairs

Got a scrape, crack, or soft deck on your power boat or sailboat? Here’s a quick, easy fix that will save you money. There are many different ways to go about the repair, but my method works and is not too difficult to master.

Let’s get started fixing that crack.

Did your jib pole come loose? Did the anchor swing too wildly or did your landlubber friend forget to tell you he had on his golf shoes? Don’t laugh…it happens. I used to get all upset when I saw the slightest damage to my gel coat and thought it would never be the same. You will always see it even after a mint fix. But no one else will, even if the fix is not perfect. Power boats get cracks here and there from the pounding as they cut through waves. Sailboats get it the same way, plus all the heeling over they do.

I have read all the books and articles and found they all do a great repair. Some more complicated than others. I took the best from each and now do this procedure for a great fix.

What you’ll need:

1. Get a Bondo can (auto/marine body filler), that is short and wide, with a plastic top. This comes with the catalyst you will need.
2. Sandpaper/wet & dry (emery cloth), 1 sheet of each: #220, #320, #400, #600
3. Gel Coat color from the manufacturer – it’s worth the wait to get it. If not, you can use white gel coat with the tints you need to get it right. Most stores have a chart.
You can mix the gel coat over the winter. Get the right color card from Home Depot, and you can play with the color over the winter, until you get a match, and save it in a jar for the spring.
4. Acetone
5. Masking Tape
6. Spray bottle, sold in marine supply or hardware stores.
7. Screwdriver or metal pick
8. Newspaper

As you can see from the materials list, there need not be a great expense in performing your own repair. These materials can last through 10 repairs. Each time you take care of the crack yourself, you can save yourself hundreds of dollars.

1. In order to repair a crack, clear the area. Take a good look at it and then take some acetone on a rag and clean in and around the crack. A little goes a long way. Too much is no good. This cleans the wax, dirt, and stains off so you now can see clearly how far the crack really goes and what color you should mix, too. The factory gel coat that was sent is the original color of the boat’s gel coat. By sanding lightly with 300 grit wet you will bring this color out, but it will not match the rest of the boat. You may have to add a touch of yellow or gray/black to get that faded color. Look from the sun. If you plan to compound to the original color, then go with the factory color, otherwise, tint it down.

2. Now that the gel coat is ready, let’s get back to the crack. After using some acetone and sanding right around and in the crack, use a flat hand screwdriver or metal pick to loosen any material in the crack. Make good, fat edges at either side of the crack. Chip away at it until you get to good, un-cracked gel coat. Sand the area, blow out and acetone again.

3. Tape around the area you are working on, close to the crack. Then tape newspaper around it to catch any over-spray.

4. If the crack is deep, you need to add some plastic filler (bondo). You can use the type that has fiberglass strands. A white colored filler is preferable. Mix the proper amount of catalyst into the filler and squeeze it into the crack. If the crack is small, use a flathead screwdriver. Keep it just in the crack. Use masking tape along the edges, if you need. You can keep it level with the surrounding gel coat, because when it dries, you will sand it lightly with the 220 or 300 grit and make a slight depression in the plastic. Drying time will vary according to the temperature and amount of catalyst used. Pull the excess masking tape away. Use acetone to wash away the masking tape glue and any impurities.

5. Get the sprayer, read the instructions. Pour the gel coat (factory or mixed) into the jar. Add some acetone to cut the thickness of the gel coat so it can spray out. Add the proper amount of catalyst, stir and screw the jar back on and you’re ready to go.

6. Find a piece of cardboard to spray on. Feel the force and the amount that comes out of the sprayer. Press the nozzle to move it to the right. Release nozzle. Press the nozzle again, move to the left and so on to get a smooth coat. Now, spray the repair area with the same motion. See how it looks before you repeat the process. Don’t try to complete it in one or two shots. Slow and easy. It will cover. You can put extra coats on because you will do sanding next. Don’t put too much on. Let it dry. It’s good to do this in 70 – 80 degree weather. If it is cooler out, point a utility light at it. It should harden it in anywhere from 15 minutes to an hour, varying according to the outside temperature. If you want, you can leave it overnight. If it still doesn’t set, use the acetone to get it off and try again with a better combo of catalyst. You will get good at this one you do it several times, just like riding a bike.

7. After the gel coat hardens, take that plastic cup top and put some water in it. Rip a 1″ x 4″ piece of emery cloth off the 220 or 300 grit. Soak it a bit and also put some water over the repair. Wipe it around. Now, with the emery cloth pliable, lightly sand over the repair. Feel the coarseness of the area you are sanding. Add more water if it feels pretty flush with the surrounding area. Move to 400 grit, then to 600 grit. Get it nice and wet. Watch not to take too much gel coat off. Do a little checking as you’re sanding.

8. The final step is using a little white compound. Add a touch of water. Compound out lightly. Wash off thoroughly and wax. You’re done. Is it perfect? Maybe, but if not, no will see it unless you put blue gel coat where white should belong. In the meantime, you will forget about where it actually is as it fades in. A scrape is basically the same, just a large area. Sometimes a light sanding with 300 or 400 grit, nice and wet, will remove most and sometimes, surprisingly, all of the scrape without a gel coat repair. It just depends how deep it is.

With a little practice, you can save yourself a boat-load of money otherwise spent on having the gel coat refinished professionally. If doing it yourself is not your thing, you may find understanding the process helpful when consulting with a repair center.