Any way to build composite gunnels with out a vacuum bagging rig?

[bark-eater]

Is it possible to construct composite gunnels on a canoe with out a vacuum bagging set up? I get that there will be way more resin left on the boat than optimum, but my alternative is vinyl, so their is a lot of room for a strength to weight improvement. I can visualize a couple ways to go about it, but would rather not reinvent the wheel if possible. Thanks, Woody

 

[stripperguy]

I’ve built a couple boats with fully composite gunnels (gunwales)
I used H80 Divinycell, with a slot cut on the underside to fit over the sheer. I epoxied them in place with Cabosil thickened epoxy, applied with a corner snipped ziplock bag into the slot.
Once the foam was firmly in place, I shape the gunnels to my desired profile and faired them at the same time.
I hand laminated some bias woven carbon fiber tape, maybe 13 oz? Bias woven to conform to the compound curves, and tape so not to have any stray fiber edges.
The carbon fiber did what you would expect in that it absorbed a gallon of resin, or so it seemed.
I paid a heavy weight penalty as a result.

On my next fully composite gunnel, I’ll just use some thinner glass and pigment the resin, carbon is overkill, imho.
The gunnels have held up well to my cartopping and general neglect and abuse.

 

[Alan Gage]

I've done it multiple times using multiple methods with carbon over cedar. I've gotten some good results but they've always been a PITA. I won't be doing it again.

Alan

 

[Jim Dodd]

I have always glued and screwed my Ash gunnels. I glue and screw, the inwhales , and glue the outwhales.
Coating my Ash gunnels, with multiple coats of Watco, has always been sufficient.

You can scratch Watco, and it doesn't show White, like epoxy coatings, or varnish will.

Presuming weight being your main reason. I have seen race hulls, that just use a thick strip at the shear , and glass.

What purpose do you expect this canoe to preform ?

Jim

 

[Cruiser]

Hi Woody,
A few years ago, a building friend did up a Freedom 17 and used composite gunnels. His method and results were about the best I have seen, I just looked at that link, but the image links don't seem to work atm, so I have requested him to look at them and if he gets it fixed, I will post a link to that build.

Brian

 

[bark-eater]

Thanks for the replies. I would prefer wood, but since moving south, every boat with exposed wood started growing mushrooms. I've improved the storage situation a bit, but at this point replacing wood with wood seems like pissing into to the wind.

 

[Traveler]

I’ve had good results using a cedar “uniwale” as stripperguy described, but with 8 oz carbon fiber sleeve. Probably not as light as a foam core, but still came out to around 3 pounds all-in for 3/4 x 7/8 gunwales on a 14 foot pack canoe. And the wood is totally encased in carbon and epoxy so no worry about mushrooms, and no need for vacuum bagging.

Make the wood gunwale and dry fit until you are happy with it. Then round the corners etc. so you don’t snag the carbon, run it through the sleeve and liberally brush on epoxy. A gloved hand works great to squeegee it nice and tight, and get rid of excess.

Once it is dry to the touch, cut out the carbon that covers the slot in the gunwale with a box knife, and you will find that it is still flexible enough to follow the sheer line and attach with thickened epoxy. Finish up with additional epoxy to fill the weave, along with varnish for uv protection.

 

[bark-eater]

Cedar seems like it would have some stiffness to help keep the hull fair. I assume that I would have to be more careful with the hull shape using foam. At this point I have 3 composite hulls and one Royalex hull that need gunnels.
At least one of the composite hulls is earmarked to be a partially decked sailing canoe so the gunnels would be wider and have various attachment points and patrubences. Unfortunately all that will have to be engineered by trial and error.

Just to add to the mess is a fiberglass Maine Pea Pod, which is basically a really wide canoe, with rotten gunnels.

But narrowing back, the first hull that needs attention is a beat up kevlar Mad River Malachite...

 

[Traveler]

I should also mention that once on the boat, I put a layer of fibreglass cloth over the top of the gunnels before filling the weave, in order to provide better protection of the carbon from bumps and roof racks, etc..

 

[bark-eater]

I should also mention that once on the boat, I put a layer of fibreglass cloth over the top of the gunnels before filling the weave, in order to provide better protection of the carbon from bumps and roof racks, etc..

My first thought when I checked out Swift's composite gunnels was how are they going to hold up to abrasion. I didn't think to ask about it though.

 

[MrPoling]

Thanks for the replies. I would prefer wood, but since moving south, every boat with exposed wood started growing mushrooms. I've improved the storage situation a bit, but at this point replacing wood with wood seems like pissing into to the wind.

I'm probably going to get flamed for this, but...

If it's an old boat, and you'd like wood that doesn't grow mushrooms or need lots of maintenance, use treated lumber.

Go down to the lumber store and find yourselves some decking boards that don't have knots on the outsides. Rip the outer edges off, they'll be rounded and ready to go.

It is a good idea to wear a mask while you rip and sand treated lumber.

I've done it before, it works fine.

 

[bark-eater]

The PT wood I see is Yellow Pine. They use a low grade of Yellow Pine with wide rings so that the chemicals will penetrate better. Pre covid there was a local lumber that specialized in Yellow Pine, and you could get clear tight grained dimensional lumber that is naturally durable with out treatment. Thanks stuff is heavy and doesn't glue as well as other soft woods. Thanks for the idea, YP might be appropriate for the Pea Pod...

 

[bark-eater]

I’ve had good results using a cedar “uniwale” as stripperguy described, but with 8 oz carbon fiber sleeve. Probably not as light as a foam core, but still came out to around 3 pounds all-in for 3/4 x 7/8 gunwales on a 14 foot pack canoe. And the wood is totally encased in carbon and epoxy so no worry about mushrooms, and no need for vacuum bagging.

Make the wood gunwale and dry fit until you are happy with it. Then round the corners etc. so you don’t snag the carbon, run it through the sleeve and liberally brush on epoxy. A gloved hand works great to squeegee it nice and tight, and get rid of excess.

Once it is dry to the touch, cut out the carbon that covers the slot in the gunwale with a box knife, and you will find that it is still flexible enough to follow the sheer line and attach with thickened epoxy. Finish up with additional epoxy to fill the weave, along with varnish for uv protection.

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How would you go about attaching thwarts, handles and seats? Would adding pads to the inner edge of the gunnel work? I can visualize how to make it strong, but not how to make it look good.

 

[Jim Dodd]

Thanks for the replies. I would prefer wood, but since moving south, every boat with exposed wood started growing mushrooms. I've improved the storage situation a bit, but at this point replacing wood with wood seems like pissing into to the wind.

How you store your canoe is 90% of the problem ! I have found, after having replaced several gunnels for others. For those that don't care for their canoes ? Aluminum is my best advise !

 

[bark-eater]

The initial disaster was the first year or so with the canoes on low saw horses out side. The boat that really went from useable to unusable was a Mad River, and the wood work immediately grew mushrooms. The Pea Pod had some decay from sitting out side in a cooler state, but again the wood just melted off when it got south.

My storage situation is slowly improving. I've got a rack up that gets above the ground moisture, and eventually will get some sort of tarp roof structure to keep the UV damage under control.

I've also got a hoop garage in the works that should fit 2 or 3 boats in the rafters, but moisture will still be an issue.

This Summer we have been paddling plastic and aluminum and I need to figure a good storage system for the "Plastic Kruger" that I spent a lot of time pushing the dents out of this spring.

So all that brings a hesitation towards adding more wood to my maintenance back log....

And I have a bunch of nice hulls staring at me.

 

[stripperguy]

Thwarts, both short and long were also full composite. I attached them with Cabosil thickened epoxy, and reinforced the joints with some carbon sleeving slipped into place before epoxying the thwarts into place. The carbon sleeving was easy to blend into the gunnels, and has an intriguing look.

As for seats, they’re either attached to fiber reinforced cleats, or bottom mounted pedestals. Pedestals are full composite as well.
In any case, I have no exposed wood on any of my composite hulls.
Alan’s method of carbon wrapped cedar is an elegant and cost effective solution, IMHO.

 

[bark-eater]

I was thinking about using dowels drilled through from the outside and then composite over the joint. I haven't worked with sleaving before. I figure that If I sleaved a thwart I could make the ends long and cut them open to wrap over the joint. I have a bit of boat yard epoxy experience and was a hanger arounder at one long standing "skunkworks" Wing Systems, so I've seen some nice work done.

https://www.practical-sailor.com/wp-content/uploads/2020/02/PS1009_wingdinghy.pdf

I got to carry that canoes plug around a couple times but never got to see the finish product.

 

[Traveler]

How would you go about attaching thwarts, handles and seats? Would adding pads to the inner edge of the gunnel work? I can visualize how to make it strong, but not how to make it look good.

Some have epoxied small blocks to this type of gunnel to give extra width at the thwart and seat points - I’ve done this for bare wood gunnels, but if you shape them with a nice long and smooth bevel into the gunwale I am pretty sure they would integrate nicely with carbon sleeve as well. Although you do need to know before hand where the attachment points are needed along the sheer.

In my case, I bent some 1/8 aluminum flat bar to make resting points for thwarts, encased those in carbon sleeve, and used thickened epoxy to attach to the hull and underside of the gunwales.

I did think about adding a rivet or two through the hull for extra security, but given that it is a cedar canoe I decided not to for now - probably not an issue for the composite and royalex boats you have though, and could let you use just bare aluminum since you wouldn’t need to worry about the strength of a metal to composite hull epoxy bond.

I didn’t have handles and used a short bowline hole in the bow and stern instead - but the same thing with bent aluminum stock would also work here if you want handles.

As this was a pack canoe, the seat on this boat is simply stuck to the floor using 3M dual lock. To raise it to proper canoe height my go-to would be to use cleats. I’ve done them with wood in the past, but pretty sure you could form aluminum flat bar along the same lines as for the thwarts to get a good result.

 

[Jim Dodd]

The initial disaster was the first year or so with the canoes on low saw horses out side. The boat that really went from useable to unusable was a Mad River, and the wood work immediately grew mushrooms.

Just for the record. Mad river does a terrible job sealing their wood work.
I've replaced three sets of Mad River gunnels. They rot from the inside out.

 

[bark-eater]

Some have epoxied small blocks to this type of gunnel to give extra width at the thwart and seat points - I’ve done this for bare wood gunnels, but if you shape them with a nice long and smooth bevel into the gunwale I am pretty sure they would integrate nicely with carbon sleeve as well. Although you do need to know before hand where the attachment points are needed along the sheer.

I was thinking about this, and it seems like it would be possible to leave sections of the gunwale sleeve when first attached to the boat. That way a sleeved thwart could be butted up to the gunwale and the sleeve braid could be opened up to a fan and slid under the gunwale sleeve. If the top of the cedar was relived slightly the "bump" might be avoided.