More gelcoat issues-seeking advice.

[Dirtyfrank1]

Got another repair I want to tackle. See pictures below.

[Dirtyfrank1]

Looks to me like the gelcoat is peeling off, all the way down to the fiberglass. My plan is to scrape anything loose off, sand and repaint. Few coats of primer, few coats of rustoleum marine. And then restripe. Do you think I should skim a layer of bondo, or maybe marine tex on the fiberglass first? Then prime and paint? Or will several coats of a filling primer bridge the gap to the existing gelcoat that I don’t remove? Gonna try to have a paint store tint the paint a little to get a closer match to the old gelcoat. And use the new stripe to break up any color difference. Am I on the right track? Thanks.

[Dirtyfrank1]

And separately, why do some of pictures turn when I upload?

[Dav L]

You will have to go deep on this one. A flap sander on a right angle grinder to get the bulk off. Don't bother scraping. Sometimes that hurts the material worse.

Once you are down to where nothing is loose, then body plastic to rebuild the top surface.

You might also consider laminating new filon to the existing to eliminate all that body plastic sanding. You still need to grind down the loose stuff first.

[Dirtyfrank1]

Originally Posted by Dav L

You will have to go deep on this one. A flap sander on a right angle grinder to get the bulk off. Don't bother scraping. Sometimes that hurts the material worse.

Once you are down to where nothing is loose, then body plastic to rebuild the top surface.

You might also consider laminating new filon to the existing to eliminate all that body plastic sanding. You still need to grind down the loose stuff first.

Thanks again for your insight Dav. Most of it will flake right off. Prob grind around the edges to make sure I get back to solid gelcoat. Something like bondo what you were thinking in terms of filler? Or did you have something else in mind?

[Jim18655]

I think I'd find a replacement panel. Maybe some "fiberglass reinforced panel" (FRP) from a home center, similar to a shower stall material. Not sure about the UV resistance but paint might protect it. You could cut out the bad down to the top of the window and seam it across to the slideout. I think it might be easier since I think you'll find the backer board is probably rotten. You could replace that at the same time. Sometimes what looks fast and easy takes longer and is harder.

[Dirtyfrank1]

Originally Posted by Jim18655

I think I'd find a replacement panel. Maybe some "fiberglass reinforced panel" (FRP) from a home center, similar to a shower stall material. Not sure about the UV resistance but paint might protect it. You could cut out the bad down to the top of the window and seam it across to the slideout. I think it might be easier since I think you'll find the backer board is probably rotten. You could replace that at the same time. Sometimes what looks fast and easy takes longer and is harder.

Thanks Jim! I will get a better look after I peel some the flakes off. So far no water infiltration inside, so maybe the board underneath isn’t that far gone. Although this would be good practice for the other issue I’m having on the back. Detailed in an earlier post. For now it looks like it’s just the gelcoat that’s coming off, looks to me like the fiberglass is still ok. I’ll know more this weekend. Thanks again.

[Dav L]

If the fiberglass looks very raw, you might paint some fiberglass resin over the exposed glass to relocate it. Use a chip brush.
Then, once hard, sand rough and apply body plastic and flatten it all out.
Follow that with primer, block sand, spot putty, prime, block sand, paint.

You could also spray gel coat back on as well instead of paint.

[Dirtyfrank1]

Originally Posted by Dav L

If the fiberglass looks very raw, you might paint some fiberglass resin over the exposed glass to relocate it. Use a chip brush.
Then, once hard, sand rough and apply body plastic and flatten it all out.
Follow that with primer, block sand, spot putty, prime, block sand, paint.

You could also spray gel coat back on as well instead of paint.

Thanks again Dav!!

[Rkesselus]

Not to be aruging with any else here is how I would approach the job. Sand down till you get into a uniform glass pattern. Feather the edges of the sanded area and the solid gel coat then apply two coats of Polyester resin applying a sheet of wax paper over the coated area. use a straight edge to smooth the serface of the wax paper. Polyester will only dry completely in the absence of oxygen. You will play hell trying to match the gel coat color. If you try to spray the gel coat you will need a gel coat gun or thin the gel so much that it will run all over the place. So If I were to try to get color back on th surface I would use a polyester resin and color mix. It can be done before you add the activator, and white comes in several different shades. If you do this use the colored polyester for the second coat and then a third coat using the wax paper on each coat. Now you should have enough thickness to sand it smooth. That said I found it so difficult to match the color that on many boat repair jobs we would come up with a paint pattern that worked into the oroginal design and do both sides to match with a good quality of two part base clear coat paint

[D Gardiner]

Ouch, that looks bad. The gelcoat obviously has failed, however the underlying fiberglass with resin has also failed or suffered damage. Having repaired numerous fiberglass failures on automobiles, I truly believe you need to sand back to solid fiberglass then apply fresh resin and fiberglass woven mat. You probably only need to do two or three layers. The resin will help bind any loose fibers to the new cloth. Sand the area down level, then.....

Once you have done that, I would follow the previous posters suggestions to apply fresh gelcoat to make a water tight seal. You can primer and paint from there.

One question. Seeing quite a bit of green moss. Do you live in the Pacific Northwest? Or did the roof previously leak?

[CountryB]

I making some repairs on my coach (not as bad as yours) and I have found the "Total Boat" products to be excellent for fiberglass repair.TotalBoat

I used the two-part epoxy to fill in some deep gouges, and then the "epoxy flaring compound" to fill in voids. This stuff is tough (made for marine environment).

I would sand off all the loose stuff then see if the Flaring Compound alone is enough to fill and level the surface. If it is, you can prime and paint over it. If the damage is too deep, there are other products you can use first.

On my coach, I was surprised at how thin the actual fiberglass layer is. The wall is made of plywood (or lauan) with maybe two layers of fiberglass top of that coated with the gel coat and paint. There is really no "fiberglass" so to speak - not like you would find in boat construction where its 1/4" or thicker.

There's a YouTube site called "BoatWorksToday" that demonstrates these products and provides lots of good information on working-with/repairing fiberglass.

https://www.youtube.com/channel/UC0k...zdqFUk3oTaHBuA

[Dirtyfrank1]

Originally Posted by D Gardiner

Ouch, that looks bad. The gelcoat obviously has failed, however the underlying fiberglass with resin has also failed or suffered damage. Having repaired numerous fiberglass failures on automobiles, I truly believe you need to sand back to solid fiberglass then apply fresh resin and fiberglass woven mat. You probably only need to do two or three layers. The resin will help bind any loose fibers to the new cloth. Sand the area down level, then.....

Once you have done that, I would follow the previous posters suggestions to apply fresh gelcoat to make a water tight seal. You can primer and paint from there.

One question. Seeing quite a bit of green moss. Do you live in the Pacific Northwest? Or did the roof previously leak?

I am in central PA, though the rv was most recent homed in NY. No water infiltration inside, so I think it’s just been like pictures for long enough to grow the moss.

[tderonne]

Originally Posted by CountryB

On my coach, I was surprised at how thin the actual fiberglass layer is. The wall is made of plywood (or lauan) with maybe two layers of fiberglass top of that coated with the gel coat and paint. There is really no "fiberglass" so to speak - not like you would find in boat construction where its 1/4" or thicker.

Right, standard Filon fiberglass sheet is .045" thick. Not a lot to work with.