Gelcoat Chips Repair

Use gelcoat.

Mix up in a cup, add some thickener (milled glass fiber) to make a paste, brush onto chipped area. Cover with packing tape to help smooth out the surface. After cured, sand smooth as needed, polish and wax.

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Thanks. So I guess I could get one of those kits and try to color match the gelcoat, I seem to remember seeing something from West Marine or something like that.

Dogboy wrote: Use gelcoat.
Mix up in a cup, add some thickener (milled glass fiber) to make a paste, brush onto chipped area. Cover with packing tape to help smooth out the surface. After cured, sand smooth as needed, polish and wax.
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It is my understanding milled fiber is not a thickening agent. It is a tensile strength additive and not the best choice as a thickener (at least i was told this by a professional repair person)

I would use a silica product as a thickener (or other), and add some mill fiber for strength, but not as the main product for viscosity control

here is a pretty decent list of different additives and their primary uses
http://www.fiberglasssupply.com/Product_Catalog/Fillers/fillers.html

i prefer wax paper vs tape but to each their own

Page 26 of this west system document shows lots of data about using additives to epoxy, and it's pretty much the same with gel-coat (as far as i know)
https://www.westsystem.com/wp-content/uploads/User-Manual-2015.pdf

it's good to know the different levels and ideal consistency needed before you start mixing

Edited by MN3 on Apr 08, 2018 - 04:24 PM.

I agree, there are numerous products that can be used for thickening. I didn’t intend to imply that milled fiber was the only option although I do think it’s a good choice since it will add strength to the gelcoat. But you’re right, cabosil would also be a good option and there are some others that would work as well. Depending on where the chip is located, you may not even need to thicken at all.

sm

I have one chip at a bow tang, it's been there since I got the boat 2 years ago and hasn't changed in size or anything, it is very small but I figured I would touch it up. The other chip is at a side shroud anchor and it too has been there since I got the boat with no change in 2 years. Again, these are really kind of small chips and they are only gelcoat and not chips in the fiberglass. I saw a repair kit that uses talc as a thickening agent.

I too use silica as the thickening agent.
I also use a different material than the tape. I put a couple of layers of tape near the repair and then I tape down a piece of the slippery backing off of roofing ice dam material (over the repair). It is fairly thick and leaves a nice gloss and it only takes a little bit of material anyway. The layers of tape near it give you a bit of height to the repair that you can then sand down, once all cover and tape are removed.
There are numerous ways and methods on these type repairs, and everyone seems to have their own tricks of the trade.

martyr wrote: What would you guys recommend for small repairs like that.

For small chips and true deep scratches this is what I use. It goes on pretty thick, but you may still have to use the tape idea or something along those lines to hold enough material in place till it cures. This is the type of gel-kote called "waxed" so it will cure without an oxygen barrier. If you don't get enough void fill in one application sand the surface and apply another coat (rinse and repeat as needed).

https://www.homedepot.com/p/Aquatic-Gelcoat-Repair-Kit-in-White-35RKWH/100177610

For small chips and true deep scratches this is what I use

I didn't even know they made fiberglass tubs - how fast are they? (jk)

One thing not mentioned until Leeboweffct's post: you need to use a wax additive or similar (sanding aid) so the gelcoat cures and isn't "tacky" - (soft and will clog up sandpaper)

Wax additive: pass.

Gelcoat repair kit: Unfortunately not, the evercoat ones I've tried SUCK, they are 1 part systems and don't cure properly. Also not very useful on colored boats.

What you need: color matched gelcoat, fresh MEK, mixing cups, foam brush or Preval sprayer, green or purple PVA in a spray bottle and painters tape. This is the PVA I am talking about:

The tips on tape and cabosil are good ones, but I find the need for thickening agent isn't really there. Sand an area 2-3 times larger than the chip to be repaired, so you can feather the repair. Tape around this. Let the gelcoat harden up some (cure time is controlled with the amount of MEK you use and the temperature of the work/ambient conditions), then take the foam brush and apply to the area. Let that get pretty tacky, I wait at least 30 minutes, usually an hour. Then spray the gelcoat with PVA, or you can brush it on with a separate foam brush. PVA forms an air-tight barrier without the hassle of wax additives that clog up sandpaper.

Finishing: let the gelcoat cure a minimum of 6 hours, overnight is better. Come back in with a sanding block and 320 grit sandpaper, if you have a lot of buildup maybe 220 grit but you have to sand the low grit marks out as well so I prefer to start with 320 and work my way up (to 1500 or 2000 grit than polish). I use credit cards for small areas and this block for larger areas: https://www.amazon.com/gp/product/B003WUYG1E/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

Good luck!

Wax additive: pass.

your method sounds better

do you need to thin the gel/pva mix?

Edited by MN3 on Apr 10, 2018 - 10:21 AM.

I've personally never found the wax additive to be a problem. You just add a few drops of it when you add the catalyst. I've never noticed any issues with it clogging up the sandpaper. Clogging issues happen when you try to sand gelcoat/resin that isn't fully cured.

I think the effort/expense of spraying PVA over what sounds like some very small chips in a 30+ year old boat seems a little extreme.

sm

MN3 wrote:

Wax additive: pass.

your method sounds better

do you need to thin the gel/pva mix?Edited by MN3 on Apr 10, 2018 - 10:21 AM.

Nope, shoot it straight. I don't even spray it-I use a spray bottle from meguires: https://www.autogeek.net/meguiars-spray-bottles.html

Dogboy, you may be right, but I maintain my boats so they look like new. Spraying PVA over gelcoat is easy and not expensive, but then again I also buy it by the gallon for use in composites fabrication.

Good thread.
I need to repair a spot where a small padeye pulled out of the hull (#6 screws) and I want to fill the hole, then redrill. What can I mix with the resin (ground fiber?) before I fill the holes? I envisioned using a cheap syringe like those used for irrigating wounds to push the resin into the holes. Then gelcoat, redrill, and reattach padeye.

Edited by ropewalker on Apr 10, 2018 - 07:28 PM.

Yes, great info as usual guys, thank you for all of the input.
For what its worth,the chips on my boat are less than the size of a dime and although the boat may be 30+ years old, she looks good for her age and I want to keep her that way.

Edited by martyr on Apr 10, 2018 - 08:41 PM.

This stuff works great for cosmetic dings on white hulls/rudders:
https://www.fgci.com/item/128600/FGCI-Gelcoat-Putty-White-1-2-PINT-uses-MEKP-catalyst/
Wax is included.....just add catalyst. I'm pretty sure they produce it....never had issues with shelf life which can happen when buying at a box/hardware store.

Color matching a 30 year old yellow hull will be the problem. It's likely a different hue on different areas of the boat. The materials are quite expensive to be wasting on trial and error.

I'm pretty sure they produce it....never had issues with shelf life which can happen when buying at a box/hardware store.

FGCI either produces it or resells it under their name - I use their stuff all the time (they are local to me)

Not saying this product isn't fine but ...
This product is actually more expensive (per volume) than regular gelcoat from this same company, which you can purchase with or without wax too - (and just add MEKP)

Tint in very cheap too - under $5 a jar but not sure how/if it will mix with this putty

and you may need a second color to darken or lighten it to match - you can play with minute samples of gelcoat and tint (and mekp) to color match

I need to repair a spot where a small padeye pulled out of the hull (#6 screws) and I want to fill the hole, then redrill. What can I mix with the resin (ground fiber?) before I fill the holes? I envisioned using a cheap syringe like those used for irrigating wounds to push the resin into the holes

I would use thickened epoxy (thickened with some silica or cavisil), then add a little mil fiber for strength

I wouldn't worry about a syringe (mil fibers may clog it ), and just use wax paper to push it into the hole

I would probably re attach in a slightly different spot too since there is a fair chance there was some water intrusion in the open holes - degrading any foamcore

"Color matching a 30 year old yellow hull will be the problem."

Understandable for sure. Fortunately this boat was garage kept and covered up when outside. I keep it covered constantly.

martyr wrote: "Color matching a 30 year old yellow hull will be the problem."

Understandable for sure. Fortunately this boat was garage kept and covered up when outside. I keep it covered constantly.

i would bet color can fade/ change a little with time, even in optimal storage - so even if you purchased Hobie yellow gelcoat, from hobie ... it may not match 100%

If you don't want to match it yourself with tint -
I would personally go to the hobie forums and ask others with yellow hobies what they use (or

small color differences will not make you any slower - so who cares 🙂

Best is to take the boat by a professional gelcoat shop and have them mix you up a batch of color matched gelcoat.

I use credit cards for small areas and this block for larger areas:

Hey Sam, Are you saying you use a credit card as a sanding block?

If so, you just fold the sand paper around the card?

thanks

Yep, I just 3M 77 sandpaper to old credit cards or room keys, or often just fold it over and grip with my fingers.

For larger areas, this is the sanding block I use: https://www.amazon.com/gp/product/B003WUYG1E/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

Got it - thanks

one mo' question if you don't mind

I just purchased some PVA and am gonna try using it instead of wax
can you elaborate on why you suggest waiting 30 min to 1 hour before applying?

My guess would be to allow the gelcoat to start to kickoff and solidify so it doesn't mix/contaminate but that's just my guess.

thanks!

At work we wet sand defects out of freshly primered kia bodies by hand with a 3 inch diameter squishy foam palm sander that has a sponge in the center of it and is called a "nubby". We use 800 grit in the primer booth that I work in and the nubby is fairly flexible. I think it would work well for gelcoat repairs.

marty, do you have a link to said palm sander? That does sound pretty perfect.

Yep MN3, want the gelcoat to get a bit solid but not mix with the PVA.

Yep MN3, want the gelcoat to get a bit solid but not mix with the PVA.

cool - thanks for all the advice

Samc99us, I cannot find anything online but when I get to work tomorrow I will find out who makes the palm sander.

Okay I found out that the palm sander is made by 3M. Being not very "tekie", I still cannot seem to post pics within the forum so I created an album in the Beachcats Technical album labeled "3M 3 inch diameter palm sander" . If anyone wants to post the pics in this thread, then by all means, feel free to do so. Sorry the pics are sideways also but I think you can see that the palm sander is a bell shape and fits your hand very well. I hold on to one of these things for 8 hours a day so i know these things well. Hope this helps somewhat but I have no idea how to order the things.

Edited by martyr on Apr 27, 2018 - 09:28 PM.

album in the Technical album labeled "Palm Sander"

https://www.thebeachcats.com/pictures?g2_itemId=129876&g2_GALLERYSID=9079d71ec1f9224ee65bf4ba657010cc

so is the rolling pin to beat out any dents? 😆

Edited by MN3 on Apr 27, 2018 - 09:41 PM.