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PostPosted: September 10th, 2019, 5:40 pm 
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Looking at lightweight gunnel options for my first stripper build. Like the idea of a one-piece cedar gunnel (uniwale) as has been done successfully by a few people, and also thinking about thin laminated cedar strips to form separate inner and outer pieces. The addition of a layer of fibreglass and epoxy to either of these (and as part of the lamination schedule for the latter) seems to make sense to offset the softness of cedar, but have read several posts elsewhere from seemingly knowledgeable builders that discourage fibreglass coatings in favour of varnished or oiled gunnels, but don't really explain why. Is this just people who are used to and like the traditional approach, or is there something I am missing about using fibreglass to strengthen gunnels?

Thanks for any thoughts on this.


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PostPosted: September 11th, 2019, 6:56 am 
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Glassing the gunwales will make them more difficult to remove if damage occurs... I suppose you could epoxy them in and then glass for something really light. I went with thin ash outwales held in with easily removeable screws, the ash rabbetted out to form an L shape and that caps the top and side of the sheerline. To save some weight, I used white pine for the inwales and starting to have some regrets now since the pine is so soft it chips out easily, in spite of the outwale taking most of the abuse.

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PostPosted: September 11th, 2019, 12:25 pm 
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I epoxied the inside of the outwales, thinking it might reduce the rate of decay. It didn't, or at least not much. I also made laminated gunwales. If possible it is best to laminate them in place, as laminated spars do not bend very easily and may break first.

Can't really see how you would glass the gunwales. Aren't the angles too acute to take glass well? And you would be left with a large seam to be sanded down. Maybe wrap them? Sounds too fiddly to me.

Kinguq.


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PostPosted: September 11th, 2019, 12:48 pm 
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Gunwales are meant to be banged and rubbed, not the right place for unprotected cedar.

If you were to fibreglass them, you would really need to wrap them to seal them and from my experience, that would be a painful exercise.

Personally I would recommend sticking with a hardwood. Thin them down if you want, but hardwoods are better for the purpose.

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PostPosted: September 11th, 2019, 5:07 pm 
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Has anyone considered/executed a relatively thick (1/8") veneer of hardwood over a softwood core?


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PostPosted: September 11th, 2019, 6:21 pm 
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I did the hardwood over softwood.
As in cherry laminated to spruce.
Worked for me.


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PostPosted: September 12th, 2019, 5:12 am 
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There are many ways of making light weight gunwales, similar to the process you describe. Check out the builders forum on this site. www.canoetripping.net There are a few builders there that specialize in light weight builds, and have built gunwales using nothing but foam and carbon fiber tape.


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PostPosted: September 12th, 2019, 10:29 am 
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Thanks for this. No arguments about hardwoods standing up better, but I think I am willing to make that trade off, including epoxying them on, for a lighter weight (plus I have a bunch of 16 foot cedar boards already, although I could just save them all for my next build :D ). The idea of a laminated hardwood exterior piece over cedar is also interesting - will see what the financial and weight damage is for a thin, 16 foot cherry board around Ottawa

Thanks RHaslam - I have started to check out options from the lightweight gurus on canoetripping.net. A lot of what they are doing seems to be too sophisticated for my skill-set, but there are also a lot of more manageable approaches that people seem to have had success with.

So I haven't totally ruled out hardwood gunnels, especially thinned down ones, but do people use fibreglass or even just epoxy to provide some extra protection, even if they are screwed on? Even without the cloth a coat or two of just epoxy would seem to be stronger than varnish alone, and no more brittle, without requiring any more than the regular annual upkeep to touch up nicks and scratches. As I noted, this doesn't seem to be discussed as an option but I don't understand why not.

Thanks a lot for your responses so far - all good points that I will have to think about.


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PostPosted: September 12th, 2019, 10:32 am 
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The epoxy alone without fibreglass doesn't hold up the same way.

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PostPosted: September 12th, 2019, 11:17 am 
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I've used thin strips of purpleheart laminated to softer wood for the outwales. These have performed very well for the last 18 years.

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I've also experminted with making a one piece gunwale out of softwood, and covered it with a carbon fiber sock. Works quite well, but became so stiff it was difficult to bend so didn't use it. May work better with a much smaller cross section gunwale. The ID of the sock is increased by pushing the ends together, then when the wood core is slipped inside pulling the 2 ends apart reduces the ID nicely wrapping the core.


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PostPosted: September 12th, 2019, 3:59 pm 
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Traveler wrote:

So I haven't totally ruled out hardwood gunnels, especially thinned down ones, but do people use fibreglass or even just epoxy to provide some extra protection, even if they are screwed on? Even without the cloth a coat or two of just epoxy would seem to be stronger than varnish alone, and no more brittle, without requiring any more than the regular annual upkeep to touch up nicks and scratches. As I noted, this doesn't seem to be discussed as an option but I don't understand why not.


As I mentioned, I have done this, and it was not a great benefit. The outwales still rotted away fairly quickly. Maple seems to be particularly rot-prone. Some people think that epoxy encapsulation actually promotes rot in some situations, but I don't know if that is true. For a canoe stored outside, varnish and periodic replacement of the outwales seems to be as good as anything.

Kinguq.


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PostPosted: September 13th, 2019, 6:31 am 
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I coat all of my new gunwales with epoxy before I install them. That means all four sides. Then they receive varnish on top of that. Rot will only occur if you neglect your canoe, and leave it lying on the ground or in some other compromised situation.


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PostPosted: September 13th, 2019, 8:16 am 
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Lightjay (Jay Morrison) IIRC built a very light 35-pound canoe with cedar gunwales for a cross Canada trip. I don't think he glassed them but fuzzy memory, that was a long time ago. The build description should be in old posts with some searching. Not sure how the cedar stood up over the two years (?) that it took to do that trip.

https://www.theglobeandmail.com/news/na ... cle729325/

Yep, he used western red cedar for the gunwales, see the description for the Bob's and Osprey. No mention of glassing in the gunwales description.

https://www.paddlinglight.com/articles/ ... -tripping/

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PostPosted: September 13th, 2019, 9:00 am 
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sbaillie wrote:
...
I've also experminted with making a one piece gunwale out of softwood, and covered it with a carbon fiber sock. Works quite well, but became so stiff it was difficult to bend so didn't use it. May work better with a much smaller cross section gunwale. The ID of the sock is increased by pushing the ends together, then when the wood core is slipped inside pulling the 2 ends apart reduces the ID nicely wrapping the core.


The sock approach sounds like it could work, but you definitely need to have the gunwales shaped to the hull and sheer line before encapsulating them.

Hmmm, that could work well on some paddle shafts too, especially as part of a repair.

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