Screwed up my gunnel (literally)

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Well-known member
Feb 27, 2006
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Brooklyn, NY USA
Well, this actually happened to my friend’s 2520. I was installing Poly Planar under-gunnel speakers last night. I must've not drilled one pilot hole deep enough because when I tightened down the screw, it bottomed out and left a small bulge surrounded by spider cracks on the top of the gunnel. The screw didn’t poke through. Thankfully it didn’t happen on the non-skid so it shouldn’t be too hard to repair. Funny, I installed these same speakers on my boat with zero problems.

What do you guys recommend? Dremel it out, fill with epoxy, and top off with gelcoat? I’ve never done a repair like this before. I’ve filled screw holes, scratches and gouges, but this is a little different.

Here’s a pic of the damage. Sorry for the quality. It was getting dark out. It looks like just cracks in this pic, but there is actually a small bulge, kind of like a bubble, that I couldn't push down with my finger. I guess there's cracked wood behind it?


Thanks for any advice. I’d like to get this done tonight so I can sleep easy.

:oops: Dom :oops:
Ugh, to bad it happened to another's boat. If it were mine, I'd back of the screw and hope it wasn;t too vivisble, but yes ... I would get around to fixing it.

I too think the repair needs to be effected from the top, but you should be able to do so WITHUT using epoxy ... as gelcoat does NOT chemically bond with polyester-based gelcoat ... and, you only get a mechanical bond of glecoat onto epoxy when the epoxy is seriously scuffed up.

If you need a filler, use Formula 27, then top off with std gelcoat. But alas, I fear that "wound" would need to be opened up pretty wide ... :( .
What do you think I should do Dale? Open it up with a dremel and see what's underneath? I feel really bad about it and don't want to just leave it alone.
DaleH":3sqbkp1v said:
But alas, I fear that "wound" would need to be opened up pretty wide ... :( .

It's about the size of a dime. I should've put a coin next to it when I took the pic. I'm guessing it'll need to be opened to about the size of a quarter, hopefully not more than that. My friend is going to have a heart attack when I chop a hole through his gunnel. :shock:

What do you think happened underneath? I don't know what it looks like in there. What should I expect? Wood core, layer of glass, topped in gel coat? Maybe tonight I'll just open it up, clean it out, and take a pic for you.

BTW, I did back out the screw and replaced it with a shorter one. The bulge looks the same. I tried pushing down on it but it won't budge. I couldn't even peel off the cracked gel coat.
When I was at the factory watching the construction process, I noticed that the gunwhale and cabin are done in a mold just like the hull. While still upside down in the mold, they lay small thin pieces of marine ply in resin on the underside of the gunwhale and other flat surfaces, then do another layer. Looks like a puzzle going together. Guess they use small pieces rather than large peices because the resin runs between the pieces and keeps water from running the full length of a large piece. Any water intrusion would be limited to one piece.

Anyway, I'd open it up with a dremel tool (see my thread in the projects section on "gelcoat from A to Z") for tips on how to do gelcoat work. If done right, you can't tell there was a problem there.
Thanks Porkchunker. So you think I could get away with just using gel coat to fill it in?
If any depth, over 1/16", then I'd say you need a filler. I have filled holes to 1/8" with cabosil-in-gelcoat, but cabosil "can" lighten the gelcoat somewhat. Formula 27 is a slick filler that's fast to use.
I've tried using Formula 27 before, but it dries too fast for me. I put a drop of catalyst and it dries in under a minute. Maybe I need to mix a larger amount.
I just wanted to let you guys know the damage wasn't half as bad as I expected. I just grinded out the cracked gel coat, and topped it off with a new coat. Thanks for the help. 8)

I am mounting under gunnel speakers and am a bit woried about two things...
First, I don't want to drill too deep that it goes through to the top surface and
Second, I don't want to drill to shallow so it cracks as you described.
Any advice?
BTW, how did those speakers sound?
The Poly Planar speakers sound great. I have the same ones on my 2320.

Just measure twice (or more) and drill once. And buy shorter screws than the ones that come with the speakers.
5150dude":2qfefxbw said:
Second, I don't want to drill to shallow so it cracks as you described.

Any advice?

It is also using TOO SMALL of a hole in diameter that causes most cracking around a hole to me. Usually if too shallow, you torque the screw in and the head shears off. One MUST use a drill larger than the BODY size of the #6, #8, or #10 screw you're planning to use.

I also lubricate all screws going into frp with either LifeCaulk goop or wax (if it doesn't need any sealant).
Which poly planars are you guys using?
I'm in the market, the stereo on my boat sounds great, but only in the cabin. :cry: Needs some tunes outside.