You want to do everything you can to protect your boat. One place that’s susceptible to damage is the bottom of the hull. Concrete boat ramps, rocky shorelines and sandy beaches can scratch and ding the bottom of your boat. One way to avoid this is to install a keel guard. It’s easy to do,looks good and can even help improve your boat’s performance.
Step 1: Before applying the keel guard, the fiberglass mold release agents must be removed by etching or scuffing the surface. This step must be done thoroughly so that you get the full bonding qualities of the 3M adhesive on the backside of the guard. Use a 3M Scotch Brite pad to remove release agents. Etch or scuff the keel surface, taking off the gloss where the guard is to be installed. This helps remove the release agents or waxes and also helps give the keel guard’s adhesive a better mechanical bond. The supplied pad is a mild 320 grit and won’t damage the keel’s gel coat. If you have a DA sander, it can be used instead of the Scotch Brite pad. Don’t use anything stronger than a 180-grit sand paper.
Step 2: After etching/scuffing the hull, follow-up by thoroughly cleaning the area with alcohol, acetone, toluene or byline. The keel should be wiped using clean rags or paper towels and thenre-wiped with another clean rag or paper towel, again using one of the above-recommended agents. Other products such as Acry-Lac cleaner, Liquid Sandpaper, Interlux 202, or other wash solvents containing xylene or toluene with alcohol may be used. Don’t use paint thinner for this project, or any other petroleum-based cleaners for that matter, as they’ll leave a film and may compromise the bond to the adhesive. Always remember to wear some rubber gloves, and read the manufacturer’s safety precautions when using these solvents.
Step 3: After cleaning the keel area, apply a very thin coat of the 3M #94 keel primer. Squeeze the liquid from the bottle in order to wet the sponge applicator on the top. Apply the keel primer, keeping the sponge applicator wet, and make sure that the entire area where the keel guard will be installed is primed, especially the edges. The primer interacts with the adhesive to create a bond that will become stronger over time. Be sure not to confuse the primer for a cleaning agent! Before installing the keel guard, unroll it and set in the sun for 10 minutes. It shouldn’t be installed in temperatures below 60 degrees Fahrenheit. The adhesive has a protective red plastic liner that’s been scored 1-inch wide down the center. This is done to aid in the centering of the keelguard.
Step 4: Pull back the center liner or sheath 2 to 3 feet, exposing the 3M adhesive tape. Remove the sides of the protective liner, without touching the adhesive to anything that could contaminate it, including your fingers. Align the keel guard with the center of the keel, and press it on by hand or with the supplied burnishing tool. Don’t touch the adhesive and keel guard to the keel until it’s centered. Once the adhesive touches the primed surface, it’s a permanent bond. Pull back the protective strips one side at a time — up to 3 feet — and press on by hand or with the burnishing tool. Work from the center out so no air is trapped between the hull and the adhesive. Do one side up to 3 feet, then the other. Work toward the rear in 3-foot sections until completed. After installation, go over with the burnishing tool, and apply strong force and pressure.
Story by Steve Noury