How to apply epoxy inside the daggerboard trunk?

Thread starter #1
I noticed that a good section of the epoxy has worn or flaked off inside the daggerboard trunk. The fiberglass looks nice and neat still. What have people done to fix this? I’m guessing that this is one area that water gets into the hull!

signal charlie

Well-Known Member
Staff member
Well you have to get some epoxy on a stick and get a running start at the trunk. Full speed, don't slow down!

The polysester resin flakes off, we replace it with epoxy resin because it works great, is usually easy to find and is easy to work with. We have a long thin file to chip off any flakes and abrade the surface around the chip. We use thickened epoxy, premixed in a caulk tube, TotalBoat THIXO or Pettit Flexpoxy, applied with a paint stick that we rip down to trunk width with a oval shaped end on the tip. We also used a lot of Marine Tex epoxy putty in the past. Try to be as neat about application as possible, it is tough to sand, you'll have sandpaper on the end of a stick or a long bit extension with a small sander drum on the end. And remember that the daggerboard has tight tolerances to the trunk, so any extra epoxy has to be dealt with.

trunk repair.jpg

trunk repair 2.jpg

Small Boat Restoration: Daggerboard Trunk Repair and Leak Test

Ghost Rider

Planing into eternity...
Good advice, though some hands use a brush taped to the stick for thinner resin... a piece of cardboard under the well will catch any drips, and you can simply pick up the cardboard and toss it later once the resin has cured. :rolleyes:


Well-Known Member
Through my Ultimate Inspection Port, I saw some leakage past a factory-appearing band around the base of the trunk. :( I've been playing with the idea that taping the base of the daggerboard trunk, then pouring a quart of curing resin into the top, then tilting the boat to extreme angles would seal such thin leaks. When removing the tape, recovery of the resin could facilitate other lined-up projects.

I've also got a "project daggerboard" (in blue) that, with coarse sandpaper* glued on one damaged side, could be used to trim the trunk.
* I've cut 30 continuous feet of 50-grit :eek: sandpaper from a roll of about 70 feet. :eek: (Bought for $30 at a yard sale, thinking it was a tough carpet for the garage :oops: ).

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Thread starter #5
the idea that taping the base of the daggerboard trunk, then pouring a quart of curing resin into the top,
You mean plugging the bottom and filling the trunk inside where the dagger board would go?

How about sealing the bottom of the trunk using something with a rubber gasket. Fill the trunk with resin. Cap the top with another gasketed cap and apply pressure with a bicycle pump through a valve stem in the top?

Or better yet, just fill the entire boat with resin, do a “pressure test” and boom, you’ve found all your leaks and fixed them at the same time! ... might make for a heavy boat

I think the very best solution would be to take a quart of resin and see if they will let you take the boat into the Gravatron, when the fair is in town.
Thread starter #8
This is from the top and toward the cockpit. I guess i’ll need to remove whatever top coat has delaminated and then coat any exposed fiberglass?

Ghost Rider

Planing into eternity...
I like the horse better as the avatar... some clown failed to properly wet that cloth with resin, that's why it looks the cheesy way it does now. You can add resin in the hope that it impregnates the cloth, or you can get rid of that trash, lay new cloth in there and be sure to wet it up properly. Moi, I like applying a bit of resin first, laying the pre-cut cloth in place, and then making sure plenty of resin gets brushed on top of the cloth so it's fully impregnated. You can use disposable latex gloves on this job, they're great for pressing that cloth down a bit to help the resin impregnate all the fibers. Gloves get messy on the job, strip 'em, toss 'em, and don another pair till the job gets done. End result, the fully-wetted cloth should be lying smoothly in the right location, no wrinkles or air bubbles to botch the job. Minor edges or strands which refuse to comply get ground down or sanded away later... I usually apply at least one final coat of resin when I'm through with the cloth, using surfacing resin or lightly sanding & painting the final coat afterward. Good luck, it's not rocket science, keep acetone and rags handy whenever you do glasswork, throw down a piece of cardboard or whatever to catch any resin drips. Don't forget the beer, that's the most important tool required for this sort of work. CHEERS!!! :cool:
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Thread starter #10
You can add resin in the hope that it impregnates the cloth, or you can get rid of that trash, lay new cloth in there and be sure to wet it up properly.
I would like to do it right.. so here are some questions: Would I grind out the existing cloth that can be seen from the picture? If so how deep? Or do you just remove the existing coating around the clothuntil you get to solid ground, and then lay some new cloth over the existing cloth?
I need to find some xxs gloves for the kids, they can definately fit their paws in there! “I SAID; don’t touch your face!”
Am I using the semicolon correctly?
Thread starter #11
I just can’t do the horse and I don’t have any good pictures of myself.
Let me look through the library some more
I have an idea for this, but it has never been tried. If it goes badly, you would have a lot of hand sanding with sand paper around a dowel.

What I would like to try is slopping the epoxy around the trunk as usual. Then take a balloon and wipe it gently with rag that has silicone on it.
Drop the balloon in the dagger board slot and inflate until it bulges everywhere and let cure.


Well-Known Member
The idea had been mentioned a couple of years for repair of the mast step.

I liked it then, and like it now... :cool: