Other Gel Coat Repair

[speedysprocket]

So this question is for my boat. Previous owner let the swim platform rub on the dock for years I guess and the gel coat is worn to the fiber glass on both corners. It appears to be epoxy resin, which I have heard gel coat doesn't normally stick to. Any tips on how to put fresh gel coat on these two spots? I have a gel coat patch kit, with the resin and pigments...

 

[Vumad]

Check with the manufacture to see if the gelcoat will bond. If you cant find one that will, and you don't want to use paint, you can try putting down some epoxy resin, let it green, then apply some gelcoat so the two bond a little better. I don't know for sure if that would work but it's a possible option.

Worse case it chips off a bit and you patch it again.

 

[speedysprocket]

Check with the manufacture to see if the gelcoat will bond. If you cant find one that will, and you don't want to use paint, you can try putting down some epoxy resin, let it green, then apply some gelcoat so the two bond a little better. I don't know for sure if that would work but it's a possible option.

Worse case it chips off a bit and you patch it again.

Manufacturer, Maxum, has been out of business a while now, and the boat is a 1994...

 

[37]

What leads you to think your boat is epoxy and not polyester? Nearly all commercial livery boats are poly. I'd say 100% but someone will certainly know of the 0.0001% example falling outside the norm.

You should be fine using standard poly gelcoat.

 

[air blair]

Agreed with 37^ Let's say if it was epoxy. Pigment to color epoxy is the alternative but gel is my guess


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[Vumad]

Agreed with 37^ Let's say if it was epoxy. Pigment to color epoxy is the alternative but gel is my guess


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I dyed my epoxy with white pigment and it turned yellow. The epoxy and the pigment are not UV stable. Be sure to paint or clear any dyed epoxy.

 

[air blair]

There is pigments specifically for epoxy. Works well Otherwise it acts as a contaminant.


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[Twake]

So if the boat was gel coated before, why wouldn't it stick now?

Check out spectrum color, most boat manufacturers use them, so you can get exact replacement color gel.
They are very helpful. If maxum was using their gel they can get you what you need.

 

[Vumad]

So if the boat was gel coated before, why wouldn't it stick now?

The theory is that the gelcoat goes down first and the epoxy second so the epoxy is bonded to the gelcoat. In a repair, the gelcoat is trying to bond to the epoxy. It's like when you repair poly with epoxy vs repairing epoxy with poly.

Honestly I've never added gelcoat after the fact so I don't know how it bonds. I have bought skis and found poly repairs and I just pop the patch off with a paint scraper so the poly base concerns me.

However, the put down poly highbuild primers over epoxy sealers so it makes me wonder if not all poly is the same.

 

[tomski]

I really find it difficult to follow some of the responses people write on these composite threads.

 

[Vumad]

I really find it difficult to follow some of the responses people write on these composite threads.

You don't like my response?

 

[Vumad]

Here's the answer direct from fiberglass coatings, the leading composite distributor in the southeast.

Will gelcoat bond to an epoxy hull or are additional steps necessary for a lasting gelcoat repair?

Thank you.

Great question!
So, the short answer is no, it won't bond. Our technicians reccomend, that if the epoxy is thoroughly cured, to sand it down with 36 grit sandpaper, wash it and clean it and apply a layer of Vinylester Resin at about 18 mils thick. After about two hours, you can go back and apply the gelcoat. If you decide to wait a few days before adding the gelcoat, you will want to hit the resin with 80 grit sandpaper before applying. The gelcoat you will want to apply between 15-20 mils.

This is where that originated from...

https://blog-fgci.com/2016/09/13/interior-vs-exterior-gelcoat/

nterior vs. Exterior Gelcoat
September 13, 2016FGCI

Gelcoat is a big part of our business here at FGCI. When looking at gelcoat, there is a wealth of options to choose from. The most obvious first choice is the color of the gelcoat; we have a vast array of over 25 stock colors with the ability to color match to a sample you provide. Once you have the color figured out, comes whether you want to brush the gelcoat or spray it, as we have the ability to do either. Lastly, however, is the option many people have a question about; interior or exterior. Let’s look at both options so you know which you will want for your job.

Exterior Gelcoat is our tried and true standard. If our gelcoat doesn’t specify interior or exterior, then the answer is automatically exterior gelcoat. It doesn’t mean that the gelcoat is only good for external use, or the outside of a boat, it means, simply that it does NOT have wax or Sanding Aid mixed in. This means that the lack of Sanding Aid will result in a tacky finish. If you want to avoid the tacky finish, you will want to add something like Sanding Aid, Patch Booster or Duratec to the mixture. This is mainly used as your primary coat or coats as you do not have to sand between coats, given you don’t wait too long.

Interior Gelcoat doesn’t mean the gelcoat can only be applied inside, it means it has Sanding Aid or Wax mixed in. Interior Gelcoat is used as a final coat, due to the Sanding Aid allowing it to dry tack-free, it will give a nice finish. You will not want to add Duratec or Sanding Aid to this product. If you use this product as your primary coat and look to add another coat, you will need to sand it first.

Now that you know which product you need, you can buy your gelcoat with confidence. And as always, remember that we are here to help with any questions you have!

 

[speedysprocket]

Sorry, tapatalk didn't tell me about all these replies!
I assumed it's epoxy because of the color. Aren't polyester resins usually greenish...?
The color has also faded a lot over 23 years, so using the original pigment isn't very useful or worth the hassle in my opinion.

 

[RMBC Freeride]

I really find it difficult to follow some of the responses people write on these composite threads.

I think this is Tomski's way of tongue-in-cheek, semi-politely rolling his eyes at this thread... He knows more about this stuff than the lot of us combined...

Most of the responses here are way over complicated (not singling you out Vumad - it happens all the time on this forum). A 1994 Maxum, without a doubt is made entirely of polyester resins. The cheapest, highest styrene stuff money could buy back then!
Repair it with gelcoat if you want it to match (assuming you can get a matching color) and it can be sanded/polished back to shape and you'll never know it was there.... Or use epoxy if you have some around and dont care if it matches or sands/shapes/buffs back the shape perfectly - it will seal it up and probably outlast the boat. Might yellow a bit as mentioned above.

This forum gets so hung up on epoxy because it is whats needed to work with on SMC and old SN meton junk, as well as for carbon fiber, etc. Plus it is less offensive and easier to mix & work with for first-timers. But in the production boat building world, it's mainly polyester and vinyl-ester even today.

OK, sorry if that was a rant - rant over...

 

[SUPERJET-113]

I think this is Tomski's way of tongue-in-cheek, semi-politely rolling his eyes at this thread... He knows more about this stuff than the lot of us combined...

Most of the responses here are way over complicated (not singling you out Vumad - it happens all the time on this forum). A 1994 Maxum, without a doubt is made entirely of polyester resins. The cheapest, highest styrene stuff money could buy back then!
Repair it with gelcoat if you want it to match (assuming you can get a matching color) and it can be sanded/polished back to shape and you'll never know it was there.... Or use epoxy if you have some around and dont care if it matches or sands/shapes/buffs back the shape perfectly - it will seal it up and probably outlast the boat. Might yellow a bit as mentioned above.

This forum gets so hung up on epoxy because it is whats needed to work with on SMC and old SN meton junk, as well as for carbon fiber, etc. Plus it is less offensive and easier to mix & work with for first-timers. But in the production boat building world, it's mainly polyester and vinyl-ester even today.

OK, sorry if that was a rant - rant over...

@tomski better give you a "like" on this...lol

 

[Vumad]

I think this is Tomski's way of tongue-in-cheek, semi-politely rolling his eyes at this thread... He knows more about this stuff than the lot of us combined...

Most of the responses here are way over complicated (not singling you out Vumad - it happens all the time on this forum). A 1994 Maxum, without a doubt is made entirely of polyester resins. The cheapest, highest styrene stuff money could buy back then!
Repair it with gelcoat if you want it to match (assuming you can get a matching color) and it can be sanded/polished back to shape and you'll never know it was there.... Or use epoxy if you have some around and dont care if it matches or sands/shapes/buffs back the shape perfectly - it will seal it up and probably outlast the boat. Might yellow a bit as mentioned above.

This forum gets so hung up on epoxy because it is whats needed to work with on SMC and old SN meton junk, as well as for carbon fiber, etc. Plus it is less offensive and easier to mix & work with for first-timers. But in the production boat building world, it's mainly polyester and vinyl-ester even today.

OK, sorry if that was a rant - rant over...

Imagine being on the beach at the freeride, seeing a new person with a less new person working together. A very experienced person walks by, says to them "You guys are making that more complicated than necessary" laughs, and walks off. You're unlikely to think anything less than "what a prick". This is the internet though, so its different I suppose. "it's poly, use the gelcoat" would have taken less breath, been more useful, but doesn't get said because it feeds less ego.

 

[speedysprocket]

That's the worse of the two spots...

 

[air blair]

That's the worse of the two spots...

You fix it yet? I suppose I would make the gel to match for sure.


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[speedysprocket]

You fix it yet? I suppose I would make the gel to match for sure.


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No, you want to come fix it?

 

[rubbertoe]

Speedy ,i am no gel coat expert this is just a suggestion .But you might use resin (or filler) mixed a little on the hot side on the area with the exposed fiberglass so it doesn't sag ,fill it till its basically flush with the repair .Then thin some gel coat with acetone (just use white gel coat ) just thin enough to spray it out of a disposable aerosol sprayer (sprayer around 5 bucks ) mask the area then spray ,may take several coats to build it up to desired thickness .It will dry orange peel but you can wet sand it/burn it in to smooth using grits from say 150 to get rid of texture (sanding only your patch) ,500 ,then 1000,finally 2000 to polish,let completely dry then wax .for a repair that size you dont need much material were talking little pieces of sand paper .you might have to mess with material consistency a bit till you get it right ,but if you mess up acetone is your friend and works like an eraser till your repair is dry really not that difficult of a repair and will get rid of that annoying spot ,its like fixing the candy coating shell on a m&m.