Gel-coat repair may or may not be necessary when replacing a hatch rim depending on whether any damage was done to your kayak’s gelcoat when the old rim was removed. You don’t have to fill in the screw holes with gelcoat after placing the fiberglass cloth and epoxy resin over the holes, but since I was doing some additional repairs, I put gelcoat over the screw holes, as well. In case you are confused, not all of the photos below are from the repairs that I made to the hatch rim area.
Tools and Materials Needed: polyester gel-paste, gel coat colorant, hardener, mixing cup, mixing stick, vinyl/latex gloves, wax paper, masking tape, wet/dry sandpaper, mineral spirits, rags or paper towels
Step 1: For any gelcoat repair, you will likely need to do some prep work on the area that is being repaired. Using a razor blade or a Dremel tool, remove any loose pieces of old gelcoat and bevel the edges of the area that will be filled with fresh gelcoat. (You can see that a bit more work needs to be done on the repair area shown at right. There are some loose areas on the upper right portion of the repair area.) Clean the area with mineral spirits to remove any dust and oils. Allow to dry.
Step 2: If possible, get gelcoat colorant that already matches your kayak color closely. You may be able to order some colorant from the kayak manufacturer or an authorized dealer. This will eliminate the need to do color mixing which is probably the hardest part of any gelcoat repair. I generally go with any color that is fairly close because mixing an exact match is very difficult unless you have an art background.
Step 3: Once you have the gelcoat color matched to your satisfaction, put the amount of uncolored gelcoat paste needed to fill the repairs into a mixing cup (paper cup). Add the colorant to the gel paste to get the desired level of color saturation (approximately 1 part colorant to 20 parts gel-paste).
Step 4: Add the hardener to the gelcoat mixture according to the directions. Add too little hardener and your repair will not harden. Adding too much will make the gelcoat brittle. (The recommendation on the brand of gel-paste I was using was for 4 drops of hardener per teaspoon of colored gel-paste.)
Step 5: Using your mixing stick, apply gelcoat into the areas that need repair. Work out any bubbles and make sure to fill the voids completely. It is better to have too much gelcoat in your repair than too little. You can always sand down the excess. However, the best option is to apply only slightly more than is needed as this will keep the necessary sanding to a minimum.
Step 6: Cut pieces of wax paper that are larger than the repair areas and tape them over the gelcoat using masking tape. You want to exclude air from the area of the repair to help the gelcoat cure. If applied carefully, the wax paper can also help to cut down on the sanding that will be needed after the gelcoat hardens. You can also use pieces of acetate instead of wax paper, but I find the wax paper easier to work with and I always have a box of it handy in the kitchen.
Step 7: Allow the gelcoat to fully harden. Overnight is plenty long. For any repairs that will be below the new hatch rim, you can just do some rough sanding to make sure the repair area does not stick up significantly higher than the surrounding deck rim area. Using wet/dry sandpaper, sand the repair area smooth so that it is level with the surrounding gelcoat of your kayak. I keep my hose handy and regularly flush the sandpaper and repair area with water to keep the sandpaper working effectively. Do not apply any polish on the kayak deck that is below the new rim as the polish may interfere with the adhesive. For general cosmetic gelcoat repairs not related to hatch rim replacement: If you have a lot of sanding to do, start with a coarser grit to knock down the excess gelcoat and then transition to finer grit paper to smooth and polish the repair. I like to use grits from 800 to 1500 for finishing gelcoat repairs that will be visible.
In the next post, I will recount the procedure I used to attach the new replacement rim and complete the repair. Sorry about the long delay between Part 2 and Part 3.