DIY Network: Maintenance


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DIY Network: Maintenance

  1. 1. DIY Network: Maintenance & Repair,1983,DIY_13718_2... DIY NETWORK To print this page, select File then Print from your browser URL:,2021,DIY_13718_2278093,00.html GELCOAT REPAIR: GETTING STARTED From "Shipshape Boating" episode DSSB-108 -- More Projects » In this week's episode of DIY's Shipshape Boating, host John Greviskis demonstrates how to repair and maintain the finish -- or gelcoat -- on a fiberglass boat. What is Gelcoat? Boat builders start with a fiberglass mold (figure A) that is supported by metal on the outside (to make it structurally sound) and on the inside, a gelcoat over top of the fiberglass to make it smooth. To get the mold to pop out, a release wax is used. After waxing the mold thoroughly, a polyester-based material called "gelcoat" is sprayed on every square inch of the mold. The host of Shipshape Boating, John Greviskis, A chopper gun is then used to shoot out chopped-strand mat (fiberglass) along with polyester shows you how to repair resin (figure B) all over the mold. The mat and resin is rolled along the entire surface of the and maintain the finish -- mold, and then the structural fiberglass cloths are added. Once all of this cures, the gelcoated also known as gelcoat -- deck separates from the deck mold. on a fiberglass craft. The gelcoat has been designed to cure without the presence of air. Starting the Gelcoat Repair Materials: Die grinder and bits Dust mask and glasses 1,000-grit wet dry sandpaper One of the tips you'll 1,200-grit wet dry sandpaper receive on this episode is 1,500-grit wet dry sandpaper how to repair a ding to Blue masking tape your boat's exterior -- Safety glasses gelcoat. Dust mask Gloves Acetone Rags Gelcoat or tint kit Mixing sticks Plastic cups MEKP Marine wax Figure A Surfacing wax Yellow spreaders Sanding blocks Painter's tape Cavisil Buffing compound Buffer Buff pads Wax pads Terry cloth Figure B Spoke 1. The first thing you need to do before repairing gelcoat is to tape off the rub rail with blue masking tape (figure C). 2. Put on a pair of safety glasses, a dust mask and start the process of grinding out all the fractured areas of the gelcoat. 1 of 2 10/07/2006 4:35 PM
  2. 2. DIY Network: Maintenance & Repair,1983,DIY_13718_2... 3. Once you've found all the cracks and damage to the gelcoat, use a high-speed tool with a cone-shaped grinding bit on it to remove even more gelcoat (figure D) from the boat so that you get down into some un-fractured fiberglass. This will give you a solid foundation to be working on. (The loose material must be ground out). 4. Feather the edge of the repair area in order to give the new gelcoat a much larger surface area to bond to. Tip: If you don't have a high-speed grinding tool available, you can do the repair with some ordinary materials you'll find in your kitchen or garage. For example, a hand-held Figure C can opener can scratch out any of the fractured gelcoat. Just be sure to come back with some 80-grit sandpaper to bevel out the edges. 5. Clean the area by removing all the dust and loose fiberglass from the grinding by using acetone and a rag (don't ever let acetone touch your skin). Be sure to use a different section of cloth for each wipe in order to keep it dust free. Warning: If you don't remove the debris thoroughly, when the new gelcoat is applied, it may not bond properly. Figure D In the next segment, Greviskis explains the process of mixing the gelcoat and applying it to the craft. ALSO IN THIS EPISODE: Gelcoat Repair: Getting Started Gelcoat Repair: Mixing and Applying the Gelcoat 2 of 2 10/07/2006 4:35 PM
  3. 3. DIY Network: Maintenance & Repair,1983,DIY_13718_2... DIY NETWORK To print this page, select File then Print from your browser URL:,2021,DIY_13718_2278103,00.html GELCOAT REPAIR: MIXING AND APPLYING THE GELCOAT From "Shipshape Boating" episode DSSB-108 -- More Projects » Materials: Die grinder and bits Dust mask and glasses 1,000-grit wet dry sandpaper 1,200-grit wet dry sandpaper 1,500-grit wet dry sandpaper Blue masking tape Safety glasses The host of Shipshape Dust mask Boating, John Greviskis, Gloves shows you how to repair Acetone and maintain the finish -- Rags also known as gelcoat -- Gelcoat or tint kit on a fiberglass craft. Mixing sticks Plastic cups MEKP Marine wax Surfacing wax Yellow spreaders Sanding blocks Painter's tape Cavisil Figure A Buffing compound Buffer Buff pads Wax pads Terry cloth Spoke Mixing the Gelcoat Figure B Before mixing the gelcoat, you may want to consider some options: A gelcoat tint kit (figure A) that comes with a base-white product and various tubes of tint. This is a more difficult way to match the color of your original gelcoat because you have to test the various tints in with the white base until you come up with the proper color. Many times you may not get an exact match to the original gelcoat. You can use the manufactured tubes of gelcoat that are sold for most crafts as an "after" product, but remember, over time the entire surface color of your boat may change slightly, and the original product will be the perfect original color. Figure C You can get a company to match the original gelcoat by sending a sample such as a hatch to a storage area. Many companies will take sample and scan it in to a computer (figure B), where the computer will match the color. This method will give you an exact color match. This is the option that host John Greviskis went with for this particular on-air project. Before you mix up the new gelcoat, you'll need to add a few items to the mixture: Add MEKP (Methyl, Ethel, Ketone and Peroxide), which is a type of hardener used for Figure D polyester-based material. You simply add about 1 ounce of the MEKP, which is a ratio of 1 of 3 10/07/2006 4:38 PM
  4. 4. DIY Network: Maintenance & Repair,1983,DIY_13718_2... 10 percent MEKP to gelcoat. You also need some kind of agent inside the gelcoat in order to cut off the outside air supply. This agent is called a surfacing wax. Use five percent by volume here. (Gelcoat will never harden, no matter how much hardener you use if left exposed to the outside air.) The final touch is to add a thickening agent -- colloidal silica, also known as "Cavasil" -- to the gelcoat to get the right thickness (like thin paste or creamy peanut butter -- figure C). Figure E 1. Stir gelcoat mixture until it is smooth. 2. Outline each repair area with masking tape so you only get the gelcoat to the areas needed and no drippings. 3. Add enough material to the repair area so that the height of the new gelcoat is slightly higher than the height of the surrounding gelcoat (figure D). This way when it cures you can come back and sand the gelcoat down. Figure F Note: It's best to let the gelcoat cure for at least 24 hours. You want to make sure it's dry and solidly formed. 4. Using a rubber sanding block and 320-grit wet/dry sandpaper, wet sand the gelcoat down trying to stay as close to the new gelcoat (figure E). Sand the area going in several different directions. Make sure that your keep the paper wet by occasionally dipping it into a bucket of water. You want to do all the damaged spots like this. 5. Now, switch out to 500-grit wet/dry sandpaper and wet sand just a little farther out away from the center of the repair than where you sanded before. This is how you blend this Figure G area to the rest of the boat. At this point you don't want to use block sandpaper. It's easier to bevel out the edge if you use the regular sandpaper by hand. 6. Now it's time to progress to a 800-grit wet/dry sandpaper. Again taper out the sanding just a little bit further. Each time you go up in grit paper your actually sanding out the scratches that we just cut into the gelcoat with the previous grit paper. 7. The final sandpaper you'll use is 1,200-grit wet/dry. Copy the previous two steps. 8. The final sanding doesn't involve sandpaper at all. You'll use a variable-speed buffer and After your boat's gelcoat some medium course rubbing compound. You'll need compound that equates to about is repaired and shiny, it's 2,000-grit (coarse) wet/dry sandpaper. time to take it out on the water and have fun! 9. First, put a dab of the compound on a dry lambs wool buffing wheel (figure F). Smear it onto the area of the boat, applying it in circular motions. Set the speed on the buffer to 1,500 RPM and go to work. Tilt the wheel so that the top third of the pad is coming in contact with the boat hull. Rotate any slower and the rubbing compound will not adequately cut into the gelcoat, and if you rotate any faster and you might wind up burning through he gelcoat. 10. Make sure to overlap your strokes. Safety Alert: Be sure to wear safety goggles and a dust mask when buffing the gelcoat. You may want to consider wearing a protective suit as well. Tip: If the buffing wheel becomes clogged with dried gelcoat compound, a great way to clean it is to turn the machine on, insert a spurring tool (figure G). Insert the tool at a 45-degree angle and turn the buffer on. This removes the entire dried-up compound. Waxing the Boat The only thing left to do is wax, which is used to seal the gelcoat and protect it from oxidizing. It protects the longevity of the gelcoat and is what keeps it from getting chalky. Using a quality marine-grade wax, first apply it to the hull sides using a wheel. Use tiny overlapping strokes. Once you get a side done let it haze over so that it is completely dry and then use a clean terry cloth towel to remove all the haze. Note: 2 of 3 10/07/2006 4:38 PM
  5. 5. DIY Network: Maintenance & Repair,1983,DIY_13718_2... For southern climates, wax the hull every six months and the deck every three months. For northern climates, wax the hull every 12 months and the deck every six months. ALSO IN THIS EPISODE: Gelcoat Repair: Getting Started Gelcoat Repair: Mixing and Applying the Gelcoat 3 of 3 10/07/2006 4:38 PM