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Laminated gunnel questions

Laminated gunnel questions
August 22, 2017 08:29PM
Boat building has been slow this summer. Not a stand still, but alittle done every couple weeks. Fishing has been to good.

So how do you guys do it? Seems like thickened epoxy is the way to go. Wet out the wood strip and gunnel area on the boat, then thickened epoxy, clamp it up. She's getting close!!
Re: Laminated gunnel questions
August 23, 2017 04:47PM
I thought I responded to this yesterday, but I did so with the cell phone instead of the keyboard, and ...............I have bad luck with phones.

Laminated gunwales are the best. Certainly the strongest and not by a little bit. My Wood Products Engineering Manual has a few pages of double integral calculus equations you can use to calculate just how much stronger. But I only took one year of calculus and I'm not up to it. But they talk about it spoken terms too in that manual.

Laminated anything is a LOT stronger than the same thickness as one piece of wood. A lot stronger.

There are other advantages too. You can use shorter stock and you can use hard to bend woods like ash, because you are bending thinner strips as you build up the glue-lam.

The only disadvantage is that it's messy. You need to tape brown masking paper over the hull, put Visqueen on the floor to catch drips and you need to wear gloves. And you need a lot of C-clamps.

I have a tip on gloves. Cheap vinyl or latex anal examination gloves all too often rip and tear in mid operation. However, if you put on cheap medical gloves and THEN put on cheap cotton gardener's gloves you can work all day. And keep the sticky mess off your hands.



Re: Laminated gunnel questions
August 24, 2017 12:05PM
I get the thickest gloves at harbor freight, $6 for 100.

Sandy, do you use thickened epoxy after wetting out?

Seems like that makes more sense so the glue stays in place.
Re: Laminated gunnel questions
August 24, 2017 12:10PM


So far, bending is not an issue, found a couple clear Doug fir 4x4 at Lowe's, went through the whole pallet, but only one tiny knot in the two of them. Ripped to 1/4" They're 8 ft long. Boat is about 13ft. Overlapping them on every layer
Re: Laminated gunnel questions
August 24, 2017 12:48PM
Thickened epoxy for sure. Wet out with a small roller. Both surfaces. Then mix up and trowel on some thickened goo.

You can use relatively thick goo which minimized drips. Thick goo works if and only if you wet both surfaces first, with un-thickened resin.



Re: Laminated gunnel questions
August 25, 2017 03:08AM
Thanks for your help Sandy. Damn that was alot of clamps, thank god harbor freight had 3.5" C clamps on sale, $2.50 a piece!!

Wet the boat and the wood, let it soak for a bit, troweled on some putty. Tightened till good started squeezing out and the stopped. I've read that epoxy likes some thickness to be strong Vs glue wants a tight joint
Re: Laminated gunnel questions
August 31, 2017 02:58PM


Heres how she looked a couple days ago. Gunnel is pretty much done now. I sandwiched the core between 1/2" laminated Doug fir in the inside and 1" on the outside. Area where the oar locks are has another 1/2" on the outside.

I want to bolt through the gunnel for strength. Any tips on this? Anything I need to be careful of?
Re: Laminated gunnel questions
August 31, 2017 04:03PM
You have Plascore sides. Where ever you bolt through it is a good idea--if not required--to shave the fiberglass off two or three honeycomb cells so they can be puttied up solid......so bolting the gunwales through and tight at a later date does not collapse the Plascore.

This is pain to do, an extra and perhaps unexpected step and in fact a drawback of Plascore. On the other hand it's not so bad. I've done it many times and it works.



Re: Laminated gunnel questions
August 31, 2017 04:59PM
I see. I think I'm past that point now right? Since the gunnel is glued on? I can top fill alittle. I know I can stand on the plascore pre fiberglassing and it would not come close to collapsing. The glass and gunnel are on it now and I imagine that distributes the force of the bolts. Hopefully collapsing won't be a problem
Re: Laminated gunnel questions
August 31, 2017 05:08PM
Ah. Didn't know you glued the gunwale on. Bolt throuigh and tighten as much as can WITHOUT collapsing the Plascore. You'll be just fine.
Re: Laminated gunnel questions
August 31, 2017 05:08PM
Come to think of it, I forgot I tested this scenario.

I actually bolted through glassed plascore, and was really able to wrench down before the plascore started to collapse, way more torque than needed. The in and outwale should distribute the force nicely.

Sandy, did you learn the hard way regarding filling the plascore?
Re: Laminated gunnel questions
August 31, 2017 05:20PM
Not really. I assumed it was necessary from the getgo and have always filled a few cells first, at all bolt through places.

Maybe I didn't need to. I sometimes bury a threaded bolt in the plascore so the threads protrude up and out, so maybe a seat can be bolted on or off at a later date.

Once I made a decked white water boat with a Plascore deck that bolted down onto a gasket. I made all the bolt down areas quite solid. Worked like a charm.

I later glued that deck down permanently and now regret it. Bolt down white water decks are the way to go.
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