Gel coat basics

I want to buy some gel coat in two colors, for both hull and deck. The dealer had sent me some last year (obtained from NDK), but the can was empty when it arrived. It appeared that the contents had leaked through the lid, because the plastic bag it was in had the deck color in it. So now I have no gel coat.


  1. Are all gel coats compatible with each other? I’d like to buy mine in the U.S. and hopefully avoid more shipping mishaps.


  2. Does someone have a comprehensive primer on how to touch up with gel coat? I understand it’s similar to using “dookie schmutz” (two-part epoxy mixed with wood flour).


  3. What temperature restrictions exist for working with gel coat, and how long is full-cure time?


  4. What tools do I need? I assume I need sandpaper for the rough shaping, but should I buy a buffing or polishing accessory to attach to a ROS or drill/driver?

Gel repair

– Last Updated: Sep-27-09 3:38 PM EST –

1. Most gels are polyester and compatible. Try Mini-Craft of Florida for small doses.

2. Send an email to charliewilson610@roadrunner.com and I'll forward a file on Gel repair that lists tools.

3. Gel time is dependent on MEKP% and temperature but 15 to 30 minutes is an expected window.

4. As in 2 above.

another one
http://www.surfskiracing.com/Technique/Gelcoat_Scratch_Repair.html

Something to consider
Gel coat repairs are not terribly difficult, but they do require several chemicals and catalysts, special spray tools, respirator, sanding, color matching, etc, etc, etc.



It can be fun if you have access to the equipment and plenty of time on your hands.



If it isn’t critical to your boat’s performance, you may want to spend your time paddling, or fitting out your boat, or something like that.



Fun, but very, very time consuming. There is a reason that many boatyards charge $300 for even a minor ding in the gel coat.

Gelcoat repairs

– Last Updated: Sep-27-09 8:59 PM EST –

"1. Are all gel coats compatible with each other?"

Yes, gelcoat is just a form of polyester resin.

"2. Does someone have a comprehensive primer on how to touch up with gel coat? I understand it's similar to using "dookie schmutz" (two-part epoxy mixed with wood flour)."

It's nothing like working with "dookie schmutz". I have pics and instructions in a Webshots album at:
http://community.webshots.com/user/brian_nystrom-reg

"3. What temperature restrictions exist for working with gel coat, and how long is full-cure time?"

You want to work in temps around 70 degrees if possible. Colder temps slow the cure time and warmer temp speed the curing, but you can compensate somewhat by adjusting the amount of catalyst you add. Gelcoat cures to the point where you can sand it in an hour or two.

"4. What tools do I need? I assume I need sandpaper for the rough shaping, but should I buy a buffing or polishing accessory to attach to a ROS or drill/driver?"

You need sandpaper for a lot more than rough shaping. Something in the 80-100 grit range is fine for that, but you'll need wet-dry paper in 220, 400, 800 and 1200 (or 1500) for the final sanding before buffing. For that, you'll need rubbing compound and polishing compound. All the finish sanding will be done wet. For small repairs, it's easier to polish by hand.

One thing that you'll probably have lots of fun with is color matching the deck. It can be a real ordeal to get the color right and in some cases, it changes slightly as it cures. Getting gelcoat from the manufacturer won't help, as the gelcoat on your boat has probably faded from the sun. Unless your deck is a pastel color, you need to start with clear gelcoat. If you start with white, you'll never get a good match on a vivid color.

Gel coat repair
Thanks for the information in the answers above.


  1. Have a fiberglass canoe parents purchased it used in 1969. Pere Marquette brand square stern canoe built in 1950’s. This canoe was heavily used by 4 siblings and neighborhood kids for 20 years, then used by father almost everyday in summers for 10 years.


  2. Year 1980, tree limb fell on it and dented the spine and both sides almost in center of 17 foot length. Dad put fiberglass cloth patch on interior spine to give extra support to 18 inch by 24 inch area.


  3. Year 2009, over past 30 years, damaged area deteriorated and formed 7 cracks in gel coat.


  4. Several long scratches through the gel coat and can see where gel coat has worn off exterior bottom in several locations.


  5. Fiberglass under the cracked gel coat seems weak where fiberglass stretched during 1980 damage. Need to rebuild the rear seat and rotted plywood in square stern.


  6. Feel that gel coat at cracks needs to be sanded exposing original fiberglass, add resin type coating on exterior to reinforce the fiberglass at gel coat cracks, then add new gel coat.


  7. May need to cut out rear seat and remold a new one. Can email pictures. actionhomeland@gmail.com

Gel Coat Repair
Gel coat repair is easy. It can be purchased from a variety of sources. Such as West Marine, Noahs’S boat building supply, etc. I recommend getting the list of items you need from CEwilson and watch the tutorial by bnystrom after that I felt pretty comfortable about making the repair myself. Just keep in mind nothing is going to look like new maybe damm close. One last thing you want to buy finish gelcoat which gives you a hard finish.



Good luck

Gel Coat Repair
Gel coat repair is easy. It can be purchased from a variety of sources. Such as West Marine, Noahs’S boat building supply, etc. I recommend getting the list of items you need from CEwilson and watch the tutorial by bnystrom after that I felt pretty comfortable about making the repair myself. Just keep in mind nothing is going to look like new maybe damm close. One last thing you want to buy finish gelcoat which gives you a hard finish.



Good luck

Gel coat spider cracks
Does anyone have any idea’s as to what causes gelcoat spider cracks 0n a kayak? Rough handling, Sun, gelcoat to thick?


Spot impact

spider cracks also
caused by too thin layup.

A light deck that is rather flexible will develop spider cracks where it flexes a lot.

On a deck that is very light (thin, using Kevlar for example that is flexible) the gel coat might have micro cracks all over the flexible area.

A padlding buddy of mine has a high end sea kayak tha he uses in surf conditions. While the kayak is strong the deck flexes a a lot and has resulted in a deck that looks like a spider’s web. That deck can not support a kayak in a T rescue situation.

But not all gel coats are equal: some are more brittle than others, scuff easier or wear faster.

Hard to tell which gel coat is good when buying a new kayak though

The process has more effect on this
than the material itself.

skip it
Marine tex is so much easier to use than gel coat I’ve always don my repairs with it. It comes in white so that work fine for most hulls and can be painted if you care.



For Spider cracks I just use thin cear epoxy to keep the surface well sealed.



Boat were made to be used, Scratches show you are using it.

gel coat repair
Contack Plasticare 303-399-7662 they are very helpful and have print outs to get you started. Ray

Most of my repairs have been a disaster
Vinylester resin is also used in some gelcoats (kayaksport). I do not know if vinylester and polyester are compatable. I have issues with the gelcoat hardening. The gelcoats I received from Valley and P&H did not harden well unless they were put on thick in high temperatures. I tried using more mek in other batches and it did not help. I used either stretch wrap or mold release to starve the gel for air to allow it to harden and still had issues. When I used acetone to thin the gel for spraying, it got even worse. Based on my experience I suggest you do the following. 1. Preheat the hull with a light or heater. 2. do not thin with acetone. 3. lay it on thick and sand it down later. 4. be precise in the mek. 5. repair small areas and do not expand the touch up any more than is absolutely necessary. 6. buy locally made gelocat and skip the factory stuff as the shipment from europe seems to complicate things. 7. get out your wallet and let some other poor sob pull his hair out. My small repairs came out great and my big ones (entire hull bottom) were a disaster. God bless you my son. Bill

Thanks to everybody who replied
I’m printing out this thread, for starters.



To clarify, I am not touching up scratches. I am filling in abrasions caused by the J-cradles. They are deeper than the scratches I have, which I will leave alone.

9 year old NDK
Rode hard and put up wet, nice large patched hole done in gray but smooth and sound and it looks like Charlotte went to town on her with the spider cracks.



Leave it alone, hell no. I want her to be re gelcoated entirely on the hull and will find someone willing this winter. It is easy to say skip it or that’s what boats are made for when it is not your boat but like everything else, different strokes.



it is unlikely I will own a brand new anytime soon so why not take into account I bought her for 900 bucks and spend a couple 300 bucks to make her new to me?



I will have what I want at a third the price of new and can enjoy that little pucker the first time I scrape that slick GC on an oyster bed just like the folks who can afford brand new.

$300 ???
If you find someone who can do it for $300 and make it look so new you are worried about scratches, I want to know how it goes! That means I can really start using my boat and quit worrying about repairs that will be needed down the road.

250 for the whole bottom
so i am told and they have good references. jaybird is gonna need some to after his run in this past weekend.



I will go a year without washing my truck and maybe wash my boat twice a year except after the salty stuff. It’s not that I am bent out of shape about how bad the hull of my boat looks, I just think I deserve it since i scrimp on so many other things. It will make me feel better and that is good enough reason.

$250
Plus it will probably add 5 lbs to the weight of the boat, but hey maybe that does not matter to you. Good luck I think that’s a great price.



This a great thread which has increased my knowledge and I say use that boat and do not worry about the scratches.