Gel Coat Repair Question

[bbheli]

Hello all

I'm new here and new to boating. Im wondering if the spectrum colors gel coat is ok for this repair. My plan, 1 pick out all loose particles. 2. Lightly sand with dremel coan shaped grinding bit. 3) fill with marine epoxy. 4) spay with gel coat, 5) sand, 6) buff

Any suggestions would he so appreciated.

By the way, how do these happen.I think last year there was a little blistering but not sure.

 

[monk-monk]

Re: Gel Coat Repair Question

Glad you posted this Thread, I too need a little education about Gel Coat repairs. Does it have to be sprayed on? Is it for filling deep surface scratches? How does one select a kit to best match colors? Tell us more!

 

[sasto]

Re: Gel Coat Repair Question

I wouldn't spray gel-coat over epoxy, it will spider, crack, and delaminate. What we have done is mix gel-coat with a filler of your choice. Micro baloons or cabasil, depending on hardness you desire. I like to place wax paper over the mixture and smooth it out with a plastic squeege, which reduces sanding. Sand and buff.

 

[Yacht Dr.]

Re: Gel Coat Repair Question

Hello Heli...

Yup..those are blisters. ( Most do not understand "why" as of yet and some speculate .. ) .

I speculate its from uncured resin and being submerged in H2o.. turning the uncured resins into Glycol .. blistering happens ( Im not a chem or Sci Engeneer so sue me if im wrong ).

You should grind out like you said and fill with what was there.. Gel to Gel and Glass to Glass.. If It does not intrude in your glass then just fill with gel paste ( Cabosil and gel mix ) fair,prep,spray and finish with sand/polish meathod.

The thing about filling only with paste is that it does not "seal" the repair. you Will have water migrating into that repair and cause a failure at some point..

Epoxy is not needed nor recommended for this ( Epoxy is not IMO needed in Poly boats ).

Preval sprayers are Sweet.. you have to reduce the gel to a sprayable viscosity ( trying to spray Gel out of the can is basically Impossible ). Adding agents such as Duratek or Patch Aid .. mixed with Acetone or MEK ( solvent.. not hardener ) will help Greatly in the application of gel/spray repairs.

Just remember your Hardener ratio.. most is 1-1.5% ( 10 cc/Qt ) .. or 10 drops per oz. .. some resins/gel ( low VOC ) requires 2 % ..

Hope this helps..

YD.

 

[sasto]

Re: Gel Coat Repair Question

Geez, I was looking at the boat in the background. Guess I can't see what's in front of me. Don't take my advice.

 

[bbheli]

Re: Gel Coat Repair Question

YD

Thanks for your reply. Can you clarify what you mean by

"The thing about filling only with paste is that it does not "seal" the repair. you Will have water migrating into that repair and cause a failure at some point.."

If I should only fill the gel coat is that what you call paste?How can I repair it to prevent water migration into the repair.

If I am only to use the gel I would use spectrum colors. I'm not sure how deep you can fill with gel coat. They don't seem deep enough for filler.

How thick is the gel normally. The boat is a 93 crownline

 

[ondarvr]

Re: Gel Coat Repair Question

Are the defects only along the strake or chine (can't exactly tell from the pic)?

If it is, it can be caused by the builder using putty to fill that area making it easier to get the air out while building the hull. Its commonly used in a small radius or tight area so air doesn't get trapped right next to the gel coat while rolling the glass.

The problem is depending on the putty used and how its applied, it may not bond as well as it should to the gel coat, resulting in blisters only where the putty is.

If this is the case, you can remove the blistered surface and rebuild it with gel coat or marine type filler.

 

[bbheli]

Re: Gel Coat Repair Question

Well I'm not sure. Is the section where both surfaces meet the keel, they are right above that on one side. Here is a picture that a bigger angle of the boat. They look bigger in this but they are not, this is a zoom. I think this is the chine but im not sure, i'm to green to know.

Im in pursuit of how to fix these.

Thanks again all.

 

[ondarvr]

Re: Gel Coat Repair Question

When you backed off in the pic it looks like its just chips from the keel scraping on rocks.

The chips can be filled with just about any marine grade product, if you want it to look as good as possible then you can go with color matched gel coat, it won't be an exact match due to age though. Or you can pick up something local that is sort of the right color if that doesn't bother you. Marine Tex will work also.


If you pick at them and they are blisters, its best to remove them and build the area back to match the surrounding surface.

 

[sasto]

Re: Gel Coat Repair Question

I am back to my first post after seeing the damage better. Dosen't look as bad. I agree with ondarvr, looks like scratches from rocks. If there is no laminate damage, I would use a putty mix.

 

[Yacht Dr.]

Re: Gel Coat Repair Question

YD

Thanks for your reply. Can you clarify what you mean by

"The thing about filling only with paste is that it does not "seal" the repair. you Will have water migrating into that repair and cause a failure at some point.."

If I should only fill the gel coat is that what you call paste?How can I repair it to prevent water migration into the repair.

If I am only to use the gel I would use spectrum colors. I'm not sure how deep you can fill with gel coat. They don't seem deep enough for filler.

How thick is the gel normally. The boat is a 93 crownline

Hello BB..

What I mean by Only filling and finishing with a " patch paste " ( which is basically gel coat mixed with Cabosil ( Cabosil does not change the color of most gels and thats why its used )).

Lemme put it this way.. you have some kinda of matching " patch paste " so you die grind the repair... put some paste in there.. then sand and polish it to shiny brand new. Now when you are done with this kind of patch ONLY repar it Will look very nice and hard to even see. The Problem with this is that microscopically it will NOT SEAL the repair itself. Remember H2o consists of 2 of the smallest elements and will get into that "seam of the repair.

Spraying over the repairs "encapsulates" them from water intrusion.

Spectrum is getting much better at there Color mixes and I have no problem with using them as a "factory" gel supplier.

You can fill as deep with gel paste as far as the OEM gel is ( basically..sometimes the gel is way to thick in the first place, however I try to fill substrate to substrate .. Gel for Gel and Glass for Glass. Keeping the density the same ..

Make sure you fill Xtra high with gel paste because of its shrink factor. Or you will find yourself filling again .

How thick is gel normally .. heh.. that All depends on Where it was made and Who sprays the mold . Typically around 20-30 mils .

YD.

 

[sasto]

Re: Gel Coat Repair Question

There is a sprayer sometimes used for gel-coat or paint on samll jobs, Preval is the name. I have learned there are many ways to do any job, depending on your craftmanship skills and type of service your boat is in. Sometimes when everything is going right with a repair, something may go wrong. Be prepaired. Lots to learn here. BTW, the Dr. is very good at explaining his knowledge.

 

[bbheli]

Re: Gel Coat Repair Question

Ok, thanks so much. I think im getting this now. Am I right to think that after I patch I should spray over to encapsulate the repair. I cant imagine a a spray to work to fix these as the depth if probably noting that could be sprayed. Gel coat is im told what makes the boat waterproof so I sure don't want microscopic leaks. I guess the seams where the old meets new is the weak link do do I fill with a filer and then spray gel? 20-30 mills? that don't seem think, like a candy wrapper im thinking

 

[Yacht Dr.]

Re: Gel Coat Repair Question

Hello again BB..

20-30 mils in construction.. not allways in repairs ( the dark colors yes ).

Its kinda simple actually when you get the hang of it..

GELCOAT ONLY REPAIR.

1. Fill and Fair ( scuff/dremel, fill with X, sand smooth or even a little low ).

2 Prep ( scuff spray area typically with like 220 grit and mask off for spray ).

3. Wipe and spray ( mix as directed ).

4. Sand and buff ( typically 320-400-600-1200 then compound ).

YD.