Fixing gelcoat gouge/damage in gunnel cap.

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Well-known member
Feb 17, 2006
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Normandy Beach, NJ
I just got my boat hauled out and blocked in front of my house. It is apparent during the hauling out process that a nice 1 cm X 8 cm gash/gouge/whatever has been created on my starboard cockpit gunnel cap facing the exterior of the boat.

I am posting a few pictures with the hope that you can tell me the best way to fix it. I do not want to take it to a dealer, or have the yard that hauled it out fix it (well maybe as alast resort), rather I'd like to use it as a learning experience and try to do it myself.

Thanks in advance...


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I just read your A-Z thread Porkchunker; thank you. May I ask a follow up?

Do you have a tip to "keep the curve" in the gunnel cap? The area is gouged out flat right now, so it seems like I would have to "build it up" a tad before applying gelcoat? How do I build it up so as to retain the same curve, or close?

Also, are there temperature restrictions for doing this repair? Might I have to wait for the next 60 degree day (which might be springtime)?

ParkerSal":2qomer9w said:
Do you have a tip to "keep the curve" in the gunnel cap?
What I advise is you make a template out of thin plastic that you can put onto the radiused corner. Use thin plastic so you can file it to match the exact profile between washboards (top of gunnel), the radius, and then the vertical gunnel surface.

Machinists do use tools called a radius gauge but those are set for true 90-degree angles and you will probably have a custom angle, of which the degree doesn't matters, just make a good template from the same spot on the other side of the boat and adjust to fit fore & aft of the repair area.

How do I build it up so as to retain the same curve, or close?
Looks like you're not down too deep, I'd try straight gelcoat first. Might even need a 2nd coat before sanding in or even a 2nd application after blending in the first attempt.

Also, are there temperature restrictions for doing this repair?
Only restriction per se would be the number of drops aded to the hardener, as that is where temps come into play. Too low a temp and it may take a while to cure. If you could get a mid 60s day it should cure enough to sand in an hour or two.

Now when sanding ... patience my boy patience! You also never want to sand without a sanding backer block or you'll dish the area. Matching the radius will be tough 'cuz if you go too deep when sanding, you'll flatten the radius somewhat.

My advise would be to build up the area surrouding the wound with blue 3M tape and sand in long fore/aft motions, but never in the same spot, working the entire radius from top to bottom or bottom to top.

Layout the blue tape "next" to each other and not over each other so you can still use your plastic template as a guide. Also, you should be rinsing your wet/dry paper every 30-seconds ... and again, GO SLOW.

I've sent you some gelcoat articles, most of which I've posted here. Good luck!
I would use a long stiff sanding block. I bought 12" blocks (one stiff and one flexible) for working the keel are of the little woodie (see my signature) from Jamestown Distributors. Lay out the blue tape sufficiently left and right down the gunwhale to keep the long block from scuffing as you work the radius.

Here is a link to Jamestown Distributors that shows both the rigid and flexible boards: ... ryId%7E452
GREAT tip Dave!

A longer backer block will help tremendously.
I have had success using marine tex covered with saran wrap. The saran wrap will allow you to pull the marine text to shape. It may take a few trys before it sets up.

Avoid inhaling fiberglass dust particles when sanding, drilling, or working an area. A common practice is to spray Shaving Cream on the surface. The foam barrier will help minimize the amount of airborne dust and the Shaving Cream washes off without leaving a residue. Above all, wear a respirator. :roll:
? If you fix it now, what will they do to it when moving it back in the Spring. You paid them to move the boat, not to damage it. They should fix or pay to fix. That should be their responsibility. If they can not move the boat without damage, you need to be looking for another operator.
I hear ya stankbait. I haven't even called them since they dropped it off Saturday night; they would likely fix it without a fuss. I could make a stink, but its not worth it. I look at it as a chance for me to learn how to do this.

Thanks for the email. One of my colleagues on my old Whaler board is going to come help me repair it. Quick question: can white MarineTex be tinted and used? I think the area will need to be built up a bit. I am wondering if properly tinted MarineTex by itself will look reasonably good without a layer of Parker gelcoat on top of it.
ParkerSal":1ikrigvl said:
I am wondering if properly tinted MarineTex by itself will look reasonably good without a layer of Parker gelcoat on top of it.
To me, it will look like crap and if it doesn't now ... it will even more so in a few years when the sun fades it differently than it does the gelcoat. I also find m'tex cannot be finished anywhere near as smooth as gelcoat, not will you ever be adequately able to gelcoat over it, as the epoxy-based marinetex is incompatible with the polyester-based gelcoat.

If you need to build up the area, mix some cabosil with your gelcoat, though leave it a touch less than the needed finished surface height, using straight gelcoat for that. I LOVE that trick mentioned above in regards to using the stiff plastic to form the patch to the surrounding hull!

Gotta love CP for the tech tips alone, no?
The repair was affected thanks to advice here, and the generous nature of a total stranger from my whaler forum, who joined me this brisk morning to git 'er done.

We used a gelcoat repair kit, tinted the fiberglass gelcoat imperfectly, taped, got the heat lamp cooking, and got it curing great. After my Whaler buddy left, I sanded and wet-sanded, and then went inside and mixed another batch. I repeated the sanding process, and the curve is perfect, although the color is not. I am content that the are is protected, and more importantly I feel good that I now how to do this sort of thing well. Come Springtime I will do it over with my new expertise, patience, and with original Parker gelcoat.

I am happy this worked out. Although my back is sore from washing and waxing the boat. Thanks everybody.....