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Carbon composite canoe build help and advice please

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On283

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Hi Folks.

This post is a basically a 'carbon' copy of a post a post from another site, but after posting and running through this site...looks like there might be a lot of expertise here! Please do chime in:

After recently fixing up a few canoes, I became interested in building a composite canoe. The goal is to use an existing ~16’ tandem canoe as a male plug (not to be destroyed), layer s-glass, carbon fiber, s-glass, then either carbon over foam for trim out or wood (tbd).

Here are some basic points:

Goals:

  • Generally match the profile of the existing hull with minor tweaks such as lowing the sheer line and tightening up the beam.
  • Achieve an ultralight canoe with more emphasis on weight reduction than longevity or durability (…or comfort and stability). Flat water only. Aiming for 30-40lbs finished weight.
  • Determine if this is a project style I want to repeat with further improvements/adjustments in the future.
Notes:

  • I am aiming for a release agent, either chemical/liquid/wax, film, or peel ply over the existing boat; hand layup of all layers, squeegee, then filling and finish.
  • I recognize that I may have to split the ends to remove the new hull from the existing.
  • The existing hull has a built in wide keel that I hoping with add some rigidity to make up for a foam football floor or ribs.
  • This is not a ‘forever’ canoe…this is a can it float, is it rigid enough for flat water, how light did I get it, is it worth the time to repeat with bagging or bagging and infusion, and did I enjoy the process.
  • I don’t mind being a bit reckless with design and build, if it doesn’t pan out, I will consider the few hundred bucks the cost of exploring the process.
  • I’ve contacted the original manufacturer and they couldn’t give a hot dang about what I am planning on trying out.
More on the plug:

  • Sub 16’ prospector (ish), glass, molded keel, very old. 42 lb hull, total 53lb with new pine and ash trim out.
  • It was (probably) 35”ish max width and 34 at the yoke. I slimmed her up a bit when I replaced gunnels/seats/yoke. I have enjoy the change, makes it more fun for leaning over for tooling around on glassy water.
  • Approximately 60 square feet of hull surface area, but the new hull will be lose between 1 and 1.5” at sheer line, I have not calculated new projected sqft.
  • I will likely pop off the gunnels and fatted her out to 36 at the yoke to assist in performing as a plug and give me a chance to achieve a bit of pre-tension in the new hull (maybe a really bad idea…let me know).
Layup/construction:

  • Peel ply
  • 4oz S-glass
  • 5.8oz 3k carbon twill
  • 4oz S-glass
  • Kevlar stern and bow protection
  • Either glassed wood or just wood, or carbon over closed cell foam gunnels (only inners, no outers).
  • Seats may be webbed wood frame, or carbon of similar design, or just angled kneeling thwarts fore and aft like I have used in asymmetrical tandem canoes for solo. Similar construction for the yoke, deep dish yokes have never felt that great to me and I am not a fan of pads.
I have a few questions and would love some advice on the following:

  • Would the above result in anything close to a useable boat? Or just an expensive version of a paper boat…
  • Will the built in keel/molded keel help enough to prevent oil-canning?
  • Should I build according to the above, then test float and address issues with either another layer or two of carbon, or give in and add the foam core or other supports before the interior glass?
  • I have found some folks on this forum and others that have undertaken similar projects but not too many that have done it exactly this way, and if anyone did…I guess they didn’t post about it.
  • My very optimistic math on fabrics and resin says that with the layup described above, it I might be able to get close to a 25lb hull if I know what I’m doing (which I do not, but I am handy) and I think I can figure out a 6-10lb trim out which would get me into my desired weight class. Please let me know if think this is fantasy!
I am new to the forum, but am keen to hear from anyone with experience, especially if you’ve done this and want to ‘try’ to set me straight before I order the materials.



Thanks!
 
  • This is not a ‘forever’ canoe…this is a can it float, is it rigid enough for flat water, how light did I get it, is it worth the time to repeat with bagging or bagging and infusion, and did I enjoy the process.
  • I don’t mind being a bit reckless with design and build, if it doesn’t pan out, I will consider the few hundred bucks the cost of exploring the process.
  • I’ve contacted the original manufacturer and they couldn’t give a hot dang about what I am planning on trying out.
Click to expand...
Welcome. You're outside my wheelhouse but I like the attitude and I'll look forward to following along if you post a build thread.
 
I think you’ll have a challenge to replicate that external molded keel. That section will surely add some stiffness to the hull, but you may be surprised at how local that stiffening might be.
Keep your carbon on the inside, where its tensile strength is best suited. Definitely keep the stems open until you pop the hull off of your plug.
It seems you want to avoid foam for stiffening the bottom, but there is no better bargain strength to weight wise. As long as the foam is well adhered to the hull, you’ll gain impressive hull rigidity. Maybe you’ve seen the pic of me standing in my simply supported carbon copy Kite…
Anyway, sounds like you have reasonable expectations and like to experiment, have fun and keep us posted.
 
Thanks for the reply stripperguy, you're one of the folks here I was really hoping would chime in. I had "heard" of your carbon copy kite but the photos in the 2017 are now dead (so I thought). I had enjoyed going through the thread even without the photos but it only just occurred to me to look at some of your other posts to find some photos--nice job! And only just now I see you had a link to all of your photos buried in the post--and footage! fantastic! as well as a lot of photos on deeper pages in the threat....Evidently I didn't review the post thoroughly.
Now that I'm looking more closely at your build, I see that it is a gold mine and answers most of my questions, probably all of them once I actually review it thoroughly.
My spitball plan now is to lay one layer of carbon, one layer of glass, then add as necessary from there under the assumption that foam or something similar will be required as a stiffener. So much for a quicky 3 layer shell-in-an-evening job--I am also seeing that my initial material list was pretty...conservative. With the thought of doubling carbon and having some spare s-glass, I'm looking at considerable quote, so this project may actually have to float!
Do you mind if I shoot you a PM once I've done a bit more research?
Thanks!
 
I've built several canoes, using a similar method as you describe .
I just finished up a 38 Spl. ( Bruce Kunz design.)16'3" about 29" wide.
So I use a Stripper as a Male mold.
Using a stripper, has the advantage, of also using the forms, to build a 1/8" thick, Cedar insert, instead of foam. My insert is stripped on the same forms as the stripper. This enabled me to duplicate the insert shape and the hull shape.

If you can vacuum the insert to the inside of the hull, you will do yourself a big favor!
I opted to strap the forms on top of the insert to force it, to compress the insert to the hull, with resin and filler mix, between the hull. I had mixed results. One ? I could have used more epoxy/filler mix.

So for a release ? I cut and taped, window heat shrink film, over the foot ball of the mold. Then coated the sides of the mold, with Partal. Three brushed on coats.
Using just Partal for the whole hull ? I was afraid I would have trouble getting the hull to release easily. The film works good.
The hull has quite a bit of Tumblehome. The Partal held the wetted fabric good to the hull, on the sides. Plastic wouldn't.

So for my Lay up, I went with one layer 6 oz Kevlar.
Now here is where you can save some weight, and resin. Peel Ply doesn't conform well over the multi curves of a canoe , without wrinkles. I'm advocating using plastic film, in place of Peel ply, to reduce the amount of fill coats.. Here in lies the problem ! Getting the plastic on the wetted cloth, by yourself !
This is what I will try on my next build.
So my layup.
On top of my prepped hull. I wet out the Kevlar. I let it cure just past the tacky stage. Then apply 4 oz S-glass. Plastic film over the wetted S-glass, will reduce at least one fill coat.
Yes, Leave the ends open.

One note. The outwhales must be removed if you are starting with a finished canoe. In my case I'm using an unfinished hull, for my mold. No trim.
After the lay ups have cured, I wait several days. The hull removes easily.

I set the hull in some saddle stands, with support between the saddles. I had a hull collapse on me once. A hard lesson to learn. At this stage the hull is still flimsy.
Now is when I add the insert. Again save yourself some headache, and vacuum bag your insert, whether you use foam, or make a wood insert !

Once the insert is glued in ? Feather the edges of the insert.

I used 6 oz E-glass on mine, and glass the inside, on top of the insert, up to about the 4" water line. In the area of the seat ? Ill add another layer of cloth. I used 4 oz S-glass, as I had some scrap.

That is my hull.

I used Bell Aluminum gunnels, and Plastic end caps. I also build large flotation chambers on the ends.

I'll try and answer questions. To date I've built 7 composites. I make my seats, and they are heavy at 2.5#

Of course I varnish the hull.
This one came in at 37#. I'm very happy with it, except some of my glassing could have been better !

No Oil canning with this method. the 1/8" cedar insert adds plenty of stiffness.
Sorry for so much information, and long post !
https://hosting.photobucket.com/2d1...dbe90ede9.jpg?width=320&height=320&fit=bounds

https://hosting.photobucket.com/2d1...de65b384a.jpg?width=320&height=320&fit=bounds

My previous composite.
https://hosting.photobucket.com/2d1...6450d1ed8.jpg?width=320&height=320&fit=bounds
 
Last edited:
I've never been a fan of keels.
I would look for a different hull. You will spend a lot of money on this build. You want to be happy with it.
A keel will present more problems, than any benefit perceived to be gained. Glassing over it is the one, I would be concerned about.

I would also lean to Kevlar as opposed to Carbon fiber. Carbon really only adds stiffness, that can be made up for, in your insert.
Kevlar adds more strength, and durability.
My thoughts.

Glad to see others interested in a composite build. A Great way to reduce weight, and still have a hull ready to take on the Wilderness.
 
Another thought on your layup.
A single layer of Carbon alone, won't add as much stiffness as you think.

An insert over the football, will serve you better, unless you plan to add more layers, in place of an insert.
Certainly doable !

Good Luck !

Jim
 
On283 said:
Hi Folks.

This post is a basically a 'carbon' copy of a post a post from another site, but after posting and running through this site...looks like there might be a lot of expertise here! Please do chime in:

After recently fixing up a few canoes, I became interested in building a composite canoe. The goal is to use an existing ~16’ tandem canoe as a male plug (not to be destroyed), layer s-glass, carbon fiber, s-glass, then either carbon over foam for trim out or wood (tbd).

Here are some basic points:

Goals:

  • Generally match the profile of the existing hull with minor tweaks such as lowing the sheer line and tightening up the beam.
  • Achieve an ultralight canoe with more emphasis on weight reduction than longevity or durability (…or comfort and stability). Flat water only. Aiming for 30-40lbs finished weight.
  • Determine if this is a project style I want to repeat with further improvements/adjustments in the future.
Notes:

  • I am aiming for a release agent, either chemical/liquid/wax, film, or peel ply over the existing boat; hand layup of all layers, squeegee, then filling and finish.
  • I recognize that I may have to split the ends to remove the new hull from the existing.
  • The existing hull has a built in wide keel that I hoping with add some rigidity to make up for a foam football floor or ribs.
  • This is not a ‘forever’ canoe…this is a can it float, is it rigid enough for flat water, how light did I get it, is it worth the time to repeat with bagging or bagging and infusion, and did I enjoy the process.
  • I don’t mind being a bit reckless with design and build, if it doesn’t pan out, I will consider the few hundred bucks the cost of exploring the process.
  • I’ve contacted the original manufacturer and they couldn’t give a hot dang about what I am planning on trying out.
More on the plug:

  • Sub 16’ prospector (ish), glass, molded keel, very old. 42 lb hull, total 53lb with new pine and ash trim out.
  • It was (probably) 35”ish max width and 34 at the yoke. I slimmed her up a bit when I replaced gunnels/seats/yoke. I have enjoy the change, makes it more fun for leaning over for tooling around on glassy water.
  • Approximately 60 square feet of hull surface area, but the new hull will be lose between 1 and 1.5” at sheer line, I have not calculated new projected sqft.
  • I will likely pop off the gunnels and fatted her out to 36 at the yoke to assist in performing as a plug and give me a chance to achieve a bit of pre-tension in the new hull (maybe a really bad idea…let me know).
Layup/construction:

  • Peel ply
  • 4oz S-glass
  • 5.8oz 3k carbon twill
  • 4oz S-glass
  • Kevlar stern and bow protection
  • Either glassed wood or just wood, or carbon over closed cell foam gunnels (only inners, no outers).
  • Seats may be webbed wood frame, or carbon of similar design, or just angled kneeling thwarts fore and aft like I have used in asymmetrical tandem canoes for solo. Similar construction for the yoke, deep dish yokes have never felt that great to me and I am not a fan of pads.
I have a few questions and would love some advice on the following:

  • Would the above result in anything close to a useable boat? Or just an expensive version of a paper boat…
  • Will the built in keel/molded keel help enough to prevent oil-canning?
  • Should I build according to the above, then test float and address issues with either another layer or two of carbon, or give in and add the foam core or other supports before the interior glass?
  • I have found some folks on this forum and others that have undertaken similar projects but not too many that have done it exactly this way, and if anyone did…I guess they didn’t post about it.
  • My very optimistic math on fabrics and resin says that with the layup described above, it I might be able to get close to a 25lb hull if I know what I’m doing (which I do not, but I am handy) and I think I can figure out a 6-10lb trim out which would get me into my desired weight class. Please let me know if think this is fantasy!
I am new to the forum, but am keen to hear from anyone with experience, especially if you’ve done this and want to ‘try’ to set me straight before I order the materials.



Thanks!
Click to expand...
Hey on283, welcome to the forum.

I've not seen many factory boats that were fiberglass and carbon. My impression is both are very stiff.

I have a fiberglass.Mad River Explore. It is wonderfully stiff, and doesn't even need foam reinforcement.

Kevlar, on the other hand, is normally reinforced with foam, carbon fiber or fiberglass. I guess it is strong, but not necessarily stiff.

I'm wondering if adding carbon fiber to a fiberglass layup really does much. I'm sure it will look cool. But in the end it will be a fiberglass hull.

For a first build I'd use a layup that others had used successfully. I recommend carbon kevlar, just because it's my favorite of the canoes i've paddled.

Good luck, and keep us poste
d on your build.
 
Sorry I'm a bit late to the party. I've been busy this week.

Sounds like a fun project. It looks like you've already begun modifying your plans, which I think is good. I was concerned the original plan would be too weak. And with the cost and time involved in building a DIY composite hull it's not something you want to get wrong.

I would be tempted to approach it the opposite way than you're looking at it. Knowing you already plan to build a 2nd hull based on this experience, rather than trying to build it as light as possible and possibly ending up with a throwaway hull it might be better to ensure that your first hull is solid and useable. Then you would be in a better position to determine where you think you can cut material while maintaining enough strength.

One thing to keep in mind is that hull shape will make a big difference in terms of stiffness. The narrower and rounder the hull is the more stiff it will naturally be. Pretty much any canoe I've seen with a keel has also had a flat bottom. The flat bottom will make the boat more prone to oil canning. I built a full composite tandem canoe and, if I remember correctly, it had 9 layers of cloth (kevlar, carbon, and 'glass) in the bottom center of the hull and it still tended to oil can. It was a fairly flat bottom. Other hulls with more rounded profiles use much less cloth yet have more stiffness.

I think a core (foam if you're looking for lightest weight) will likely be a necessity based on your hull type.

I'd also be worried about following the contour of the keel when laying up the hull. I'm not sure how sharp the inside and outside corners are of the canoe you're using for a mold but if they're too sharp you might have a hard time keeping the cloth tight to the mold.

The more I work with carbon and kevlar cloth on large layups like canoes it seems the less I like it. It sucks up a ton of resin and can be difficult to work with. Without infusion or vacuum bagging to compress it I wonder how efficient it really is at saving weight for us DIYers. While I usually don't think twice about wetting out double layers of fiberglass I've always regretted doing simultaneous layers when one (or both) of them are carbon or kevlar.

I built a canoe with inwales only. It's a lightweight canoe and was built for easy day paddles so it works out fine. But one thing I did not consider until the canoe was built and I actually started using it was that the outwale gives you a place to hook your fingers or thumb when lifting the canoe. It feels noticeably more precarious lifting the boat without the outwales.

I hope I'm not sounding like too much of a naysayer. It's fun to experiment and try things and I think you'll do fine. Those are just some things that came to mind that you might give some thought to along the way.

Can't wait to see how it goes!

Alan
 
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