Fibreglass repair

[Nakoda boater]

hey all,
Doing a resto on a glass hull and when removing the trim tabs all the paint and Gelcoat got ripped off in the process. So the question is what steps do I take to getting it filled while sealing ate the same time.
Thanks

 

[Nakoda boater]

https://www.westmarine.com/buy/trav...-putty-repair-kit-gray--P0153718?recordNum=18
Would this work?

 

[tubber]

Are you putting trim tabs back on but with fasteners in new/different holes?
Is there anti-fouling bottom paint?
Will the final finished surface be paint or polished gelcoat or bottom paint over gelcoat?
The answers to these questions will guide which products you need.
Pictures help.
Marine-tex is good stuff but the little package doesn't stretch too far for the price.

 

[Wild Bill]

Have a picture?

 

[Nakoda boater]

Are you putting trim tabs back on but with fasteners in new/different holes?
Is there anti-fouling bottom paint?
Will the final finished surface be paint or polished gelcoat or bottom paint over gelcoat?
The answers to these questions will guide which products you need.
Pictures help.
Marine-tex is good stuff but the little package doesn't stretch too far for the price.

New bottom paint over sanded down old bottom paint over original Gelcoat.
I’ll take some pictures in the morning.

 

[ericl]

The West Marine epoxy should be a good option. Heresay say epoxy will stick to the existing FRP better than anything else & epoxy is waterproof where FRP/Gelcoat are not.

 

[absolon]

watch for compatibility issues

"Epoxy resins are not compatible with polyester gel coats as the gel coat will not bond to the epoxy resin. Epoxies are also incompatible with many fiberglass mats, including our chopped strand mat."

 

[Nakoda boater]

 

[Nakoda boater]

Epoxy or polyester resin with some Colloidal silica would probably be a better choice?

https://www.westmarine.com/buy/west...al-silica-filler-5-1-2-oz--323618?recordNum=1

 

[Nakoda boater]

The West Marine epoxy should be a good option. Heresay say epoxy will stick to the existing FRP better than anything else & epoxy is waterproof where FRP/Gelcoat are not.

Excuse my ignorance but what is FRP?

 

[Foxsea]

watch for compatibility issues

"Epoxy resins are not compatible with polyester gel coats as the gel coat will not bond to the epoxy resin. Epoxies are also incompatible with many fiberglass mats, including our chopped strand mat."

West System did testing and like many things, proper preparation is critical :
“As with many products, the surface must be prepared properly: if it is not, then poor curing and adhesion may result. Polyester materials can be affected by amines in the epoxy hardener. If the hardener has not fully reacted with the epoxy resin ( cured) or the amine blush is not removed from the cured surface, problems can occur. Proper surface preparation will prevent these problems. (See our Fiberglass Boat Repair & Maintenance manual, for details.)” You can get excellent bond strength with polyester over epoxy coated wood or fiberglass.

 

[Foxsea]

Excuse my ignorance but what is FRP?

Fiber reinforced plastic...

 

[Wild Bill]

40 grit, poly and colloidal to plug up the holes, maby a layer of glass over top and bottom paint. Nothing much to worry about imo..

 

[absolon]

You can get excellent bond strength with polyester over epoxy coated wood or fiberglass.

The point I was making is that compatibility is an issue and that it is a mistake to make assumptions without doing your research first. The manufacturer I quoted gave specific prohibitions; following their advice or any other suppliers recommendations ensures you don't end up with a problem.

 

[Wild Bill]

Epoxy can go over anything however don't use with mat as epoxy won't disolve the solvent used to bind it together.
Polyester won't stick to epoxy.

 

[Foxsea]

Epoxy can go over anything however don't use with mat as epoxy won't disolve the solvent used to bind it together.
Polyester won't stick to epoxy.

Myth. As the West System people say, it won't stick unless you remove the epoxy amine blush first. I've followed their recommendations for proper prep when doing repairs and have had excellent results. You can find the testing results on line.

 

[Foxsea]

The point I was making is that compatibility is an issue and that it is a mistake to make assumptions without doing your research first. The manufacturer I quoted gave specific prohibitions; following their advice or any other suppliers recommendations ensures you don't end up with a problem.

Quite right. It's always good to follow instructions for best results. There is the common myth, though that polyester and epoxy is incompatible. In fact, the best bond for transom repairs, for example, is achieved by coating the plywood with epoxy first, let it fully cure, prep it, then apply your polyester resin and fiberglass.

 

[tubber]

40 grit, poly and colloidal to plug up the holes, maby a layer of glass over top and bottom paint. Nothing much to worry about imo..

This will work fine. + Maybe drill out the holes one size because there should be remnants of old 5200 or sikaflex in them.

 

[Nakoda boater]

This will work fine. + Maybe drill out the holes one size because there should be remnants of old 5200 or sikaflex in them.

Ok, so fair it out. Over size the holes. Mix up some polyester resin and colloidal silica.

How about clean up before applying the polyester resin?

 

[tubber]

Just feather it out around the damaged areas with a small grinder. I'd go down through the gel cost to bare glass. Stuff the holes, put a circle or two of mat over that. Then decide if you want to slap some thickened gel coat to make it smoother, sand again, and paint on gel coat, sand again and bottom paint.
Or just patch, paint and fish.