Gelcoat repair -- A to Z

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Porkchunker

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I finally completed most of the gelcoat repair work on Tina's Diamond and collected the pics off the camera.

First task is to clean out the gouged/chipped area to ensure there are no loose particles and the surface is clean and rough enough to allow the gelcoat to bond. First time I did this, it hurt me more than it hurt the boat. :(
 

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Next wash the area with soap and water, dry, then wash with a solvent (I used acetone here). Soap and water removes the water soluable junk, while the solvent removes the non-water soluable junk.
 

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Next mask off the area so that you only get gelcoat on a small area. The masking tape also protects the rest of the hull when you start sanding.
 

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Next, apply a piece of ordinary clear box tape below the area to receive the gelcoat. This keeps the gelcoat in place while it hardens. Since gelcoat also needs to be kept away from the air while it hardens, the tape plays a dual role.

I mix the gelcoat in a small pill container you can buy at about any pharmacy. The ones I found came as a stack of 7 (one for each day). Each container holds about 1.3 oz of gelcoat. I usually put about about 1/2 oz of gelcoat in the container and then add 6 drops of the hardener.

In the next three pics you can see how it looks before and after the gelcoat is added and held in place with the tape. The pics are of a couple different areas I had to repair--the chine, and a long gouge on the starboard side bow. I almost cried when I saw that long gouge. BTW, all the damage came from my last trip to the CBBT when we recovered the boat to the trailer--man was the wind blowing bounding the boat.
 

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Next, I remove the clear plastic tape, clean with acetone (to remove the sticky residue from the tape), add more masking tape to protect a wider area from the sanding block. Next comes the sanding.

I use a 100 grit to remove the bulk of the excess gelcoat until I start scuffing the tape. I switch to 150 grit to take some more off, and work most of the way through the tape. When the tape is almost too thin to protect the surface, I remove the tape, and retape, but keep the fresh tape about 1/4 in. away from the edges of the new gelcoat.

Using a 400 grit wet or dry paper, I continue sanding until the gelcoat is feathered into the original surface. When you are done, you'll end up with a dull square spot where the repair took place.

I tried to take pics of the dull area after removing the tape, but the contrast wasn't good and it wouldn't show up. If you've done it right, it will be hard to see the dull area.

I don't have pics of the buffing. But from here on out, treat the area just like you would a dull/chalky area of gelcoat that has lost its shine--buff and wax.
 

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Porkchunker - thanks for the detailed instruction for the gel repair. Looks like you did a nice job. When I purchased my boat the dealer gave me two containers of gelcoat. One container is for the interior and one is for the exterior. I have not needed to use it yet thankfully. Does the Parker gelcoat come with the hardener or do I need to purchase hardener when I go to use it?

Brad
 
The Parker gelcoat uses an ordinary polyester hardener. I bought mine at West Marine. You can see the container of resin I'm using in one of the pics above.

I played a bit with the mix, until I arrived at 12 drops for a nearly full pill container, and 6 drops for one that was about 1/2 full. Since I was working with such small quantities, I had to do the best I could to calculate the liquid volume of the pill container and scale the recommended mix to something that small.

Too few drops and the gelcoat never really hardens (you can dent it with a fingernail several days later). Too many drops and it hardens too fast to work. It should set up in about 1 hour if the mix is correct. For a chip or gouge that is 1/4" x 2", the smaller quantity is plenty sufficient.

I usually prep the area and add the gelcoat on one weekend, and sand it down and buff the next. That gives plenty of time for the gelcoat to cure.
 
Great job, but I wouldn't stop @ 400 grit paper. What looks good now will show in a few years as weather beats the finish up ...

I'd step up to 600, 800, and then at a minimum 1000 grit wet/dry, using more time in the water than when sanding. Remember each succesive grit removes the scratches made by the previous one. I try to leave the tape in place 'til around 600 grit, and then feather it in with the that and the higher grades, always using a sanding block so as not to "dish" the repair area.
 
DaleH":n5iugget said:
Great job, but I wouldn't stop @ 400 grit paper. What looks good now will show in a few years as weather beats the finish up ...

I'd step up to 600, 800, and then at a minimum 1000 grit wet/dry...

I'm sure your right. None of my repairs have gone more than 1 year, so they still look good. Next time I'm at the boat, I'll mask off again and try the 600, 800, and 1,000 grit (I have all three).

I find that if after getting the masking tape real thin, then remove it and mask about 1/4" away from the new gelcoat, I don't end up with a small ridge all the way around the repair. Seems no matter how thin I get the masking tape, there is just enought to feel with a fingernail. By moving the tape out a bit, I get rid of the ridge. The dull square/rectangle is a bit bigger, but that buffs out, where the ridge does not.
 
You've done a GREAT job there Skopje :) ! I just learned the hard way on using the finer grits, thankfully not on this boat :) .
 
Porkchunker":24ermt2b said:
I finally completed most of the gelcoat repair work on Tina's Diamond and collected the pics off the camera.

First task is to clean out the gouged/chipped area to ensure there are no loose particles and the surface is clean and rough enough to allow the gelcoat to bond. First time I did this, it hurt me more than it hurt the boat. :(


Just a tip,
When you have deep chips or scratches,
mix the gelcoat with cab o sil for the 1st coat and apply it with a body filler spreader
 
You covered it A to Z Porkchunker!

Thanks for posting this. It's easier to collect all the stuff I'll need ahead of time for the job with this reference. Instead of running around tring to find stuff while the clock is ticking on the goop I just mixed up.

Great step-by-step photos.

...John
 
danielb":2syw5vy9 said:
great post and instructional presentation-here is a a suggestion though. The plastic I use to cover the gell coat is the thick hard clear plastic that you get in the collar of a new shirt or the hard plastic see thru packaging. When you tape it down over the repair tightly it squeezes the gel coat flat and smooth (very smooth) cause the plastic is very smooth and very stiff. After you get the knack how to judge how much gell coat on very little sanding will be is needed and you wont' have to put the blue tape "frame" around the site before gel coating. Just tape the plastic right onto the repair to seal out the air.

Good idea.
 
Thanks for the A-Z instructions, they are so good I am going to give it a try on my boat. Is there anything extra I will need to do if my chips and gouges are much larger and/or deeper than the one you showed in the example (someone mentioned Cab-O-Sil?). I have one on the keel that is a few inches long, and the gel coat is actually scaped off down to the fiberglass - it looks like the keel scaped along the trailer. At what point would you want to add some additional fiberglass to the repiar. Also I was at West Marine today looking at some of the gel coat repair options, can someone just tell me which one to buy. And last question: It may be a while before I get to this project, does it hurt anything to continue using the boat with these chips and scrapes. And if so, do the epoxy sticks work as a temporary fix. I saw one at West Marine called Permatex "PermaOxy 5 minute Plastic, Fiberglass and underwater repair - Looks way too easy and is way too inexpensive to be a good solution, but thought I'd ask. Thanks for your help.
 
Macfern":158tasir said:
At what point would you want to add some additional fiberglass to the repair.
IMHO if you can see fiber substrate in the area of the repair, I'd add some "kitty hair" or other chopped FRP filler to the gelcoat.

Just a precaution when using fillers ... like cabosil is "snow white" in color, therefore it can lighten the stock Parker gelcoat color somewhat, so as minimal as needed is best, or fill with the filer base and then top-coat with straight gelcoat for a perfect color match :) .

Macfern":158tasir said:
And if so, do the epoxy sticks work as a temporary fix?
I think so, and I like the one from Boater's World that is an epoxy stick where you cut off what you need, kneed it together to mix it, and then apply it ... and it will even cure underwater, which is why I keep a stick on board.

If you can see subtate/fibers, you want to protect that ASAP against future/further water intrusion.
 
Macfern":1k7ay9wd said:
...Is there anything extra I will need to do if my chips and gouges are much larger and/or deeper than the one you showed in the example (someone mentioned Cab-O-Sil?). I have one on the keel that is a few inches long, and the gel coat is actually scaped off down to the fiberglass ...

The gouge I fixed on the chine, and the long slender one on the flair of the bow both exposed the dark polyester resin under the gelcoat. They were not deep (just barely deeper than the gelcoat), so I simply cleaned them out with the dremel tool, and slathered them full of gelcoat. Have not had a problem. Key is to get the gouge clean (no loose particles/flaking) and doused with acetone to remove any oily residue before applying the gelcoat. You want a good mechanical bond between the original polyester resin and gelcoat and the new gelcoat.
 
Thanks for the "Lessons in Gelcoat." The pictures make the tehniques perfectly clear.

Your timing is excellent since I just botched the outside back of the pilothouse trying to mount some hardware. I used brass screws and they broke off. In my attempts to drill out the screws, I made a mess. You have given me hope that I can make it look good again.

BTW, the back wall seems thin and the stainless steel screws went clear through, sticking out about an 1/8th inch inside. Any advice on the best way to cover the pointed ends?
 
Bruce":12e5hhtk said:
BTW, the back wall seems thin and the stainless steel screws went clear through, sticking out about an 1/8th inch inside. Any advice on the best way to cover the pointed ends?
I'd remove the screws and cut them and then file smooth, then reinstall. I have done this too, without removing them, by careful use of a Dremel tool.
 
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