Thin Gelcoat Spot

[Timm40]

I was sanding out some scratches on my boat from Isabel and as I was lighly sanding I saw a dime size thin area where I could see resin. It''s only in one spot under the rub rail and the area is black gelcoat. Can''t I just take that area down some and back fill with black gelcoat and sand it back and buff it out?

[DelmarRey]

Tim O
Gelcoat can be sprayed on like paint and then buffed out. If you don''t have the equipment you may want to leave it to some one who does.
And scraches can be filled with a jelled gelcoat (gelcoat repair kit) then polished in. Most gelcoats are not very thick to start with. If you dig out that spot you may just open up a can of worms. I''d recommend adding more gelcoat.

[Timm40]

I''m very comfortable working with gelcoat and repairs of it.....I guess I''ll just take it down a hair and fill it back to cover the thin area. You''re right about some of it being thin.

[Sandalwood]

I'm looking through the archives for advice and this is the closest thread so far, hope you don't mind me just tagging into it.

My husband and I are working on our gelcoat on a 32 year old boat. Where some of the repairs need to be made the gelcoat is thin, so as the repair is buffed down to a smooth surface we're seeing some of the green from the glass underneath.

We're do it yourself folks but want it done right. Is spraying a thin coat the only way to make this work or is there another way of handling it? We're using West Marine Brand "Finnish Gel Coat"...

[EO32]

I've got a spot where a fender has worn the gelcoat down to the underlayment.

Don Casey's book doesn't address this specifically, but I would assume you would fill and fair new Gelcoat. He talks about putting Poly Vinyl or plastic over it while it cures to keep air off it.

[j34035]

There are 2 types of gelcoat, with wax and without. Finish Gel coat is with wax, I think. Without wax must have a barrier over the surface to cure, with wax will fully cure without this barrier. Commonly, PVA (poly vinyl alcohol) is used as a barrer. If you use waxed, you must also sand/wash the surface before applying the next coat. PVA is also sold as a mold release agent.
For small jobs, you can use the Preval spayers that have a propellent can on a glass resevoir, or for larger jobs, purchase an inexpensive gravity gun and use a compressed air source. Use Acetone to thin gelcoat, but be conservative, as a small amount of thinner goes a long way. Regardless, after spraying, you will have to wet sand with increasing finer grades of paper and then compound and polish to get a good glossy finish.
Having said all that, you can simply brush on a coat of gel coat and then block sand it smooth. This works well also. The nice thing about it is you can always sand off your work and start over if you are unhappy with it (unless you are working on non-skid!). Gel coat work is not hard but tedious sometimes, and your results do depend on your prep work, just like any other finish surface.
Also if you are spraying, mask off everything in the area, as this stuff is really hard to get off after it cures, and wear your respirator as it is very toxic if inhaled.
Good luck with your project!
DD

[sailingdog]

EO32-

If the gelcoat is made with laminating resin, then you'll need to put plastic over it, since it needs to be protected from air to cure properly. If it is an actual gelcoat, with the embedded wax, it shouldn't need to be covered, since the wax will float to the top and seal the gelcoat away from the air and allow it to cure.

Unless the worn spot is seriously worn, you probably don't need to fill it...just build the gelcoat back up to the proper thickness.

[Sandalwood]

Problem is it doesn't seem to be a worn spot of thin gelcoat, it seems that the whole coating is a little lighter than we'd like for patching and repairs. I guess we'll try brushing like a paint with a good buff and if that doesn't work we'll look at a small spray system. We've done spray work before and are well aware of all the prep you have to do for even a small job. Hoping to avoid all that if we can. The man wants it to look like she did when she was new, and thats no small trick on a well used vessel...

Yup it's a wax gelcoat, needs lots of wet sand work before and after...

[camaraderie]

I'm thinking 2part paint like Awlcare or Perfection if the goal is to look new.

[Sandalwood]

We're strongly considering getting the patch work as tight as possible and then going for a top quality paint job... I'll look at the paint types you're talking about. I want to make sure we don't end up with the nasty house paint peel that some painted top sides get. But getting the gel coat right up front is first on the list. The job is really looking quite good, except for that little ridge of green where it's too thin...