A: HELPFUL TOOLS
1. Gelcoat: from manufacturer of boat. Store in refrigerator or freezer for long life.
2. MEKP: catalyst. Treat this as you would acid. If it gets in your eyes it could blind you.
3. Dremel tool or method to clean out the repair.
4. Mixing Container: A waxed paper cup is the best. The wax dissolves and seals the repair so it fully hardens.
5. Newspaper to keep everything clean.
6. Stir sticks.
7. Paper towels.
8. Acetone for cleanup.
9. Tape: I prefer 1" green 3M fine line tape from an automotive store but masking is OK.
10. Nail or screw along with another flat applicator.
11. Sanding block: hard, flat and sized to fit your repair.
12. 320, 400, and 600 grit wet / dry sand paper.
Optional: Buffer and buffing compound such as 3M super duty or rubbing compound.
Prevail sprayer.
B: TYPES OF REPAIR
1. A CHIP: Clean out and do a gelcoat repair
2. SCRATCH: If very shallow it can be wet sanded and blended into the surrounding area. Deeper ones should be cleaned out and a gelcoat repair performed.
3. SHATTER CRACKS: Shatter cracks usually go much further out than you originally suspect. They have fingers going in all directions. A boat hit from the side may have very fine cracks 20 to 30 inch long. The cracks usually go through to the fiberglass and require that the gelcoat be removed down to the glass. If you do not repair down to the glass the crack may reappear. It should be noted that a chip and a scratch do not require total gel coat removal. Shatter cracks usually require spraying to make the boat like new. Many times shatter cracks are best left alone.
4. A HOLE: This requires a structural repair, removal and replacement of fiberglass and spraying the area.
Both the shatter crack and the hole are best done by a professional who does this work on a daily basis.
5. Hull to deck joint repair. Surprisingly this is not that difficult. See the last section.
C: BASIC STEPS TO A REPAIR
1. Protect unaffected areas. Use newspaper on the floor of the boat for instance. Why mess up what was already perfect?
2. Get out the bad Gelcoat using a Dremel tool or other device. Bevel the edges sloping into the repair area. Make sure there are no ledges. On a crack you should go down to glass. On a scratch or chip there is no need to.
3. Blow out the dust. If you suspect moisture dry with acetone or hair dryer.
4. Tape off the area around the repair. Stay close to the repair. Make sure there are no tape ends in the sanding area. The purpose of the tape is to avoid a mess and protect the area around the repair from the sand paper. It will help keep you from sanding too deep and going through the gelcoat. A professional works without this tape but it is a great aid to someone doing a repair once or twice annually.
5. Mix about 1/4 to ½ inch of Gelcoat in the waxed paper cup with 5-7 drops of MEKP. Stir completely, in addition to mixing in the MEKP, the gelcoat is dissolving the wax off the cup and this will seal the repair. You may have heard of additives like sanding aid, which serve this same function. Some people put tape, PVA or waxed paper over the repair to seal it off. With the waxed paper cup you will not need these. Too much MEKP will prevent the Gelcoat from hardening, change the color, and can generate air bubbles. Too little will just take longer to dry.
6. Fill the repair: a) use the nail point to scratch around with the Gelcoat to assure good adhesion and fill all the voids, especially the boundaries. Sort of like a dentist filling a tooth. b) Fill the repair with about 25% more Gelcoat than you think will be needed. Gelcoat shrinks and you only want to make the repair once. Be sure to get all the edges of the repair covered. Actually let the gelcoat go outside the repair area. Pop any air bubbles with the nail. Getting the air out is very important. The air bubbles will sand out as pinholes. Poor filling will leave low spots, voids or cause the edge of the repair to show. Putting on too much gelcoat will require a little more sanding but is more desirable than doing the repair twice.
7. Clean up any mess you made with a paper towel and acetone. Save the mixing cup to see how well it hardens. The cup will harden before your repair because of the volume of material.
8. Wait at least 4 hours for the Gelcoat to harden. Over night is best. Heat, such as a hair dryer will accelerate the hardening. Over heating to shorten the hardening time can cause discoloration and shorten the life of the surrounding gelcoat. You should not be able to indent the repair with your fingernail. Sanding too soon will produce a repair in which the edges show and dirt will get imbedded in the repair surface.
9. If the surface is still sticky on top but the gelcoat is hard underneath, wipe off the tackiness with acetone so your wet sand paper does not gum up.
10. Choose your sanding block well, a small block for a small repair. The block should be hard and smooth. Commercial rubber blocks are for fairing something that is already smooth like the bottom of the boat. It is too soft to do a repair or recreate a flat surface. Inside corner repairs are difficult and usually require special shaped blocks or hard thin rubber in the case of curves. You will need to put more thought and time into this type of repair. Cut the sand paper so it fits the repair. Your objective is to limit putting anything but 600 grit scratches out side the repair area. An oversize block or large uncontrolled piece of sand paper will not achieve this. The tape helps keep the courser sand paper grits off the area outside the repair. Leave the tape in place and start sanding with the 320 grit. A little dish soap in the water will help cleanse the sand paper as you work. Use lots of water. Note: You want the sanding to end up at the original surface, not above or below it. Watch what you're doing as this is the critical part of the repair. Dry the area frequently as you approach the tape so you can see and feel where you are. Stop the 320 just before reaching the tape. Use 400 to get down to the tape. Remove the tape and expand your area of sanding with 600 grit to come down to ground zero and blend in the repair. The purpose of the grits in wet sanding is speed. Each finer grit must remove previous coarser grits scratches to the point that they are totally removed. 600 grit-sanding scratches can be removed with buffing compound. 400 grit scratches cannot be buffed out. Sand randomly or you will cut groves and dish out the repair area
11. When buffing it may take 3 or more applications and buff offs. Do not burn the
Gelcoat, keep the buffer moving. On small repairs you can put the compound on a towel and rub it with your finger. It will take a little longer but you can polish the repair by hand. A little wax on top will go a long way toward bring out the luster. When you go to sell your boat and you want it looking its best. Wash it and then use Johnson's Pledge furniture polish to make it really shine and hide minor scratches.
OTHER HINTS:
Edges tend to sand through the gelcoat easily because half your sanding block is unsupported in the air. Think inward pressure and you can avoid this.
On a two side corner repair like the bow or chine's, sand the two flat surfaces first than recreate the shape of the corner last.
If you see a shadow below the sand area you are about to go through the Gelcoat and into the glass and resin. Sometimes the Gelcoat is thin before you start and once you get outside the repair it is very easy to go through. In this case leave well enough alone or the area may need to be sprayed. At McLaughlin we always spray black gelcoat behind the outside color. Black helps us visually see entrapped air easily and get it out. So if you come to black you are just about to go through the gelcoat.
Only use epoxy and Marine Tex for temporary or non-visible structural repairs. Why? Epoxy sticks to polyester, but polyester will not stick to epoxy. Therefore all future repairs have to be made in epoxy. Epoxy is much harder than the Gelcoat. When you sand the epoxy the existing surface will dish around the repair before the epoxy is removed. The epoxy is not the same color and does not look good. Why mess the boat up forever when you can make it look like new? Last Epoxy expands and contracts at a different rate than polyester as the air temperature changes. Eventually you will be able to see and feel the edges of the repair.
Hull Deck Separation
A crack can form in the joint between the hull and deck when the rail receives a very hard impact, usually in the bow. McLaughlin uses Methacylate adhesive in the bow and other high stress areas. It will never break or crack. Still with a hard impact the fiberglass may break away from the adhesive. The remainder of the joints is filled with an adhesive specially formulated for decking to produce a high strength rigid hull. Manufacturers vary in what they use. If large pieces of the adhesive fall out it most likely is polyester. If possible use a similar material to re-adhere the joint. The other alternative is to use something stronger then what is there. A thick adhesive of epoxy, Marine Tex or methacylate are ideal. The runnier they are the better to get into the joint.
Turn the boat upside down. Protect unaffected areas. Using screw drivers or wedges open up the crack about a 1/8 inch and clean out any lose material including anything that prevents the gap from closing up when clamped back together. Dry the area and wipe with acetone if possible. Find a tool like a sharpen Popsicle stick that will be used to force the adhesive into the crack. The better you spread it the stronger the joint. If the joint will not go together on its own use clamps to hold in place. Cleanup as much of the area as you can. The epoxy will not come off when hardened. After completion sand the rail to remove and roughness. Now do the gelcoat repair if there is any.
Thank you for coming to this seminar. I enjoy sharing these ideas with you and hope that it will help you in the future. Women usually can affect a repair better then men. Do not be afraid to try it. Fiberglass is very forgiving. If you're not happy with your first repair do it again.
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