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Old 16 May 2018, 05:54   #1
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Gel Coat Repair

I have a few little dings in gel coat on hull of my RIB where it has scraped off a bit as result of getting boat on trailer in bad weather. Can see the fibreglass matting.

Need recommendation for Gel Coat repair kit. Boat is International Orange.

Never done this before....so go easy on me ! Need to do a quick repairs for the summer, and will get proper job done in the winter

Ta
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Old 16 May 2018, 08:07   #2
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Quote:
Originally Posted by mikew4 View Post
I have a few little dings in gel coat on hull of my RIB where it has scraped off a bit as result of getting boat on trailer in bad weather. Can see the fibreglass matting.



Need recommendation for Gel Coat repair kit. Boat is International Orange.



Never done this before....so go easy on me ! Need to do a quick repairs for the summer, and will get proper job done in the winter



Ta


I've done quite a few "dink" repairs over the years, a bit daunting the first couple of times, but I now find it quite rewarding. With a bit of preparation, time & care, it's possible to obtain very good results. Obviously the first thing you need is gelcoat or flowcoat. Gel coat won't naturally cure in air, it stays tacky. Flowcoat is gel coat with added wax that allows the resin to cure in air. I use gelcoat & cover it with parcel tape (the wide brown stuff) to exclude air & hold it in place whilst it cures. I buy my gelcoat from Ribcraft as I know it will be a perfect match colour wise. You will also need some acetone or MEK cleaner.
Depending on what I'm repairing, I generally prep the area with a dremel with a coarse sanding drum, I usually aim to undercut the edges to give a good key for the gelcoat. If it's deep, I mix up some west epoxy with colloidal silica & fill the worst of the hole, let it cure & rough it up with the Dremel. I then mix up the gel coat & dab it in, I then stick lengths of parcel tape over the gelcoat to keep the gelcoat in place & in shape (if it's on a chine for e.g)
Let the gelcoat cure, remove the tape & start sanding & shaping. I start with 800 grit wet & dry, working down to 3200 grit with plenty of water & a dab of fairy liquid. Finish with some G3 compound & polish. If you don't like the result, grind it out & start again, you've nowt to lose. Choose a warm dry day if working outside.
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Old 16 May 2018, 08:59   #3
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I've had success with PLASTIC PADDING Gelcoat Filler, its easy to use and with a little effort a good finish is achievable. I appreciate your boat is orange and it maybe hard/impossible to achieve a colour match.
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Old 16 May 2018, 23:59   #4
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What pikey Dave said. Although epoxy under polyester can be difficult if your a newbie. I’ve had both good and bad results over epoxy. If they small chips the gel will probably dab on with a mixing stick and be fine on its own. Plastic padding is good stuff too but it does sometimes fade a different colour as it’s not an exact colour match.

I just done a gel repair. Not finished sanding yet as it’s a reasonable area and I used same gel coat that was put on from the same pot. Colour match isn’t perfect somehow but with age I hope it will fade.
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Old 17 May 2018, 02:04   #5
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I didn't know about the potential problems with epoxy, I guess I've been lucky. I had some spare West Epoxy kicking around so used it. What are the problems & workarounds?
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Old 17 May 2018, 04:34   #6
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Quote:
Originally Posted by mikew4 View Post
I have a few little dings in gel coat on hull of my RIB where it has scraped off a bit as result of getting boat on trailer in bad weather. Can see the fibreglass matting.

Need recommendation for Gel Coat repair kit. Boat is International Orange.

Never done this before....so go easy on me ! Need to do a quick repairs for the summer, and will get proper job done in the winter

Ta

The Plastic Padding Gelcoat filler is a 2k Methyl methacrylate (Perspex) and works well.

For a good to perfect colour match, just see if you can take a tiny flake of Gel coat from the damaged area and take it into your local car body paint suppliers (not halfrauds !)………… they will be able to match the colour almost exactly using base colours and tints. Then mix the paint into the Gel coat mix. Luckily solid colour paints are the cheapest ……… expect to pay £25 - £50 per litre for a solid colour, some of the fancy ChromaFlair Colour shifting paints are £400 per litre !


Once applied, smooth it off and then stretch some cling film over the repair. This will give you a good level finish and perfect edges. Once dry, pull off the cling film and then block sand using 240 grit and then progressively go right down to 1200 / 2000 grit which will leave a nice polished surface. It seems a bit of a flaff, but it is actually quite a quick job.

I have made many repairs using this method and the results are pleasing to the eye. I was lucky with the paint as my son used to be the foreman / manager of the local car body shop painters and he also used to do custom and show car paint jobs, but you will be surprised at the technology they have for getting a perfect colour match. The last repair I did was for a friend of the family, who’s yacht was damaged on a mooring by somebody (or something) running along the starboard quarter, which left a gouge about 1m long and 1cm wide. The boat was a light terracotta colour and using the above technique I was able to get an almost perfect colour match and the repair was all but impossible to see ……….. the guy was so pleased he bought me half a dozen bottles of whisky ! ……….
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Old 18 May 2018, 11:50   #7
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Quote:
Originally Posted by Pikey Dave View Post
I didn't know about the potential problems with epoxy, I guess I've been lucky. I had some spare West Epoxy kicking around so used it. What are the problems & workarounds?
There are loads of online tutorials / arguments over whether you can/should put polyester based resins over epoxy based ones. The main potential problem is the chemicals released from the Epoxy as it cures (bloom/blush) that may then cause layers above to loose adhesion. If the surface underneath is rough, and a good mechanical bond is achieved then this shouldn't be a problem. Equally the curing agent you add to the epoxy makes a difference to how much blush you get.

General advice is that if you do an epoxy repair you should leave it several days to fully cure, and then clean it with soap and something slightly abrasive to remove any blush before working over it with a poly resin like gelcoat or flowcoat.

Personally like PD I use epoxy-based resins for most repairs, and use poly resins (flowcaot/gelcoat/filler) over the top and have never had any problems on either RIBs or sailing boats.

See:

Will Gelcoat adhere to Epoxy? - Cruisers & Sailing Forums

http://epoxyworks.com/index.php/appl...at-over-epoxy/

https://www.jamestowndistributors.co...2Polyester.pdf
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Old 18 May 2018, 12:03   #8
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Quote:
Originally Posted by Andy_Rs600 View Post
There are loads of online tutorials / arguments over whether you can/should put polyester based resins over epoxy based ones. The main potential problem is the chemicals released from the Epoxy as it cures (bloom/blush) that may then cause layers above to loose adhesion. If the surface underneath is rough, and a good mechanical bond is achieved then this shouldn't be a problem. Equally the curing agent you add to the epoxy makes a difference to how much blush you get.



General advice is that if you do an epoxy repair you should leave it several days to fully cure, and then clean it with soap and something slightly abrasive to remove any blush before working over it with a poly resin like gelcoat or flowcoat.



Personally like PD I use epoxy-based resins for most repairs, and use poly resins (flowcaot/gelcoat/filler) over the top and have never had any problems on either RIBs or sailing boats.



See:



Will Gelcoat adhere to Epoxy? - Cruisers & Sailing Forums



http://epoxyworks.com/index.php/appl...at-over-epoxy/



https://www.jamestowndistributors.co...2Polyester.pdf


Thanks for that, every day's a school day
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