Building racing canoe: WRC or Composite?

Francis · Mar 13, 2019

I'm Francis from Belgium and a ultra-marathon canoe racer (5 x Yukon River Quest). Next year, I want to participate in a race in the UK with 78 portages, so I want to build a C1 canoe (see picture) as light as possible. I built already 2 strippers, but the question is now, again in WRC or in composite.

Let me first explain how I built my 2 previous strippers:
C1 - stock racing canoe simular model as the Blackwater of Savage River
17' long
cedarstrips aournd 5 mm thick
Outside: 1 layer 6oz E-glass - 3 coats epoxy - 2 layers Varnish Epifanes
Inside: 1 layer 2,8oz E-glass - 2 layers epoxy - 2 layers Varnish Epifanes
Seat + pedestral: carbon
Thwarts: alu-tube
Gunwale: only innerside - Ayous/abachi
Total Weight: 15 kg

My C2 - 18'6" long
Cedarstrips: 4,7 mm = 3/16"
Outside: 1 layer 4 oz S-glass - 2 coats epoxy - not yet varnished
Inside: 1 layer 4 oz S-glass - 1 coat epoxy - not yet varnished
Seats: Carbon
Bulkheads: Corecell laminated with carbon
Seatrails: Alu
Thwarts: Abachi/Ayous
Gunwale: only innerside - Ayous/abachi
Total weight: 19 kg

So the goal for my next build is a light and stiff C1 racer
I have different ideas and building techniques but have a lot of questions to help me in the decission:
Option 1:
Strip build in WRC thickness 1/8"
Outside: wet hand-lay-up of Carbon fibre, but with the odd shape of the boat I think I need Twill Weave Carbon, but I can find that only in 6 oz
How many coats of epoxy do I need?
Can I use vacuum-bagging and/or infusion
Some say, that vacuum-bagging don't help because it's only 1 thin layer of fabric..

Inside: 4 oz S-glass
Thwarts: Foam covered with a carbon sleeve. Corecell or an other foam?
Gunwale: Same technique as thwart
Seat: Carbon

Option 2:
Replace the cedar strips with foam strips PVC, divinycell or Corecell
What is the advantage vs cedar strips? I think the foam absorbs more epoxy resin
Laying the strips on an female or male mold?
When working in a female mold, just make 2 halfs of the hull and then join it together?
200 or 300 gr. Carbon fiber - Twill Weave for in- and outside
Is 1 coat of epoxy enough?
Is it necessary to lay a light layer of fiberglass on the outside to protect the carbon skin?

Option 3
Making a mold and do a full composite layup
Disadvantage: because it's only to make 1 boas, maybe this option takes to much work and is to expensive?

I know a guy who has experience with vacuum bagging and infusion,.so he can help me with that process.

Thanks
Francis

Alan Gage · Mar 13, 2019

This will be a fun thread!

I built an 18' 6" cedar strip semi-racing canoe with strips a little over 1/8" thick and 4 ounce cloth (e-glass) that came in right at 30 pounds. It doesn't meet USCA specs however (or perhaps you don't have to worry about specs?).

When I first started reading your thread I was going to say cedar strip would be the way to go because you're not likely to lose much weight with composite and I don't think it's worth it for on the water performance but when I saw the number of portages you'll be doing all of a sudden 5 pounds less weight makes a big difference.

A 3rd option for a composite build is to make a sacrificial wood strip mold (can be short pieces of whatever cheap wood). Put epoxy over the wood but no fiberglass. Wax the mold, coat with PVA, do your composite layup, and then once the boat is off the forms you can rip out the wood mold. I did this once and it worked pretty well.

You'll probably need a foam core bottom to get the lowest weight and that would complicate that process a little. Core would probably have to be installed after the wood mold was removed.

I'm short on time now but will check in later.

Alan

stripperguy · Mar 13, 2019

Hello Francis,
Welcome to the forum...It sounds like you've already got quite a lot of boat building experience.
I used to paddle C1's as well, that's a challenging hull shape for home building.

If your laminate schedules for WRC cores has provided adequate stiffness, then similar thickness H80 Divinycell will provide similar stiffness hulls as well.

WRC being around 22 lbs/ft^3, the real advantage of H80 foam is the density (or lack thereof). H80 closed cell foam is 5lbs/ft^3. Quite a weight savings.
It's also closed cell, so very little resin will be absorbed, likely less than with a WRC core.

If you're fully committed to using carbon fiber cloth, be sure to use it on the INSIDE, as it's biggest advantage is in its tensile strength.

Beyond that, if you come up with an ingenious method for one off composite construction, please share it. A bunch of us here are similarly wondering what would be the best technique.
I would prefer larger H80 sheets, heat formed over a male plug. Any challenging sections (like the creases in a C1) can be dealt with smaller panels and/or strips I suppose.
The problem I see is how to keep the formed foam (or strips of foam) in place until it can be sanded smooth and glassed.
Working in a female mold, with vacuum, would solve that issue, but there are many reasons to not commit to a female for only one or two hulls.

Francis · Mar 13, 2019

Thanks 'Alan' and 'stripperguy' for the input! Never heard before of the 'sacrificial wood strip mold', but that's also the reason why I do a post on this forum :-; It would be nice to see some pics of that project. I have very limited experience with Corecell (just made some bulkheads, covered with carbon), but it looks easy to fair the hull, maybe to easy. If I can use larger sheets, vs strips, then I need also less glue. What do you recommend to heat the sheets so I can make some curves and when the sheets cool down, do they keep the form? Maybe it's easier if I can install the sheets from keelline to gunwale, but is it necessary that I have more moulds on the strongback. If I go for the carbon fibre, what type do you recommend to cover the odd shape of the canoe. I guess, because of the width of the canoe, I can't cover the hull in 1 piece, so I have to join the fabric at the keelline with an overlap. So what do you think about following technique: Male mold stripped with H80 (10 mm thick), Wet-out the carbon fabric on a plastic sheet (a kind of home-made prepreg) and lay over the hull (in 2 pieces). On top of that a layer of peelply, so I have only 1 coat of epoxy. For the inside, a hand wet-layup of the carbon fabric, layer breeder, layer peelply and then vacuum bagging. Question for the inside: working with the fabric in the length or from gunwale to gunwale? Do you think that 5 oz Carbon fibre is enough? If I can use this technique, then I have 1 coat of epoxy less and the core is lighter then the WRC. Then only problem is, I need a heavier carbon fibre then then the 4 oz S-glass of my previous build. Makes that sense?

Jim Dodd · Mar 13, 2019

Hi Francis !

Any chance you might know Erik Van Woerkens, From Belgium ? He's racer, and strip builder.

If I was planning to build a serious racer, I'd start my research into Innegra !

It is the newest most advanced material out there ! Taking the place of Kevlar, in my research.

A stripper for a male mold Would be the most economical, in my opinion ! I Foam core is certainly an option. Manufacturers are going Foamless. They must have good reason !

As a release between the hull, and the mold, at least a partial layer of Plastic heat shrink film, and maybe a Partal coating PVA (liquid release agent) in the Tumblehome area.

Your option #3 sounds the best to me, if you plan to make several, and have the money for a mold, and bagging !

Welcome !!!

Jim

Jim Dodd · Mar 13, 2019

Francis · Mar 13, 2019

Thanks for the links, a lot to read and then choose the right method,... difficult.

Alan Gage · Mar 13, 2019

Francis said:
Never heard before of the 'sacrificial wood strip mold', but that's also the reason why I do a post on this forum :-; It would be nice to see some pics of that project.

It's included in Jim's list above but here it is again: http://www.canoetripping.net/forums...scussions/diy/38693-composite-bloodvein-build

In that thread you'll also find a failed attempt at infused carbon gunwales.

Ultimate light weight wasn't the main goal of that build. It was to add strength while keeping weight to a modest level.

Carbon and kevlar seem to be very resin thirsty materials in hand layup, presumably due to their greater thickness and coarser texture (also requiring more fill coats). I sometimes wonder how much benefit there is to using them if not bagging or infusing when you look at the extra cost vs. weight savings.

Alan

stripperguy · Mar 14, 2019

As Alan said, some of the kevlar and carbon materials require massive quantities of resin...If you're planning on carbon over foam gunnels, you may want to reconsider and use glass over foam. Same strengths can be achieved, but with considerable weight savings.

Better to gain strength through added section thickness, rather than high modulus cloth

Jim Dodd · Mar 14, 2019

I hope to try some Innegra, in combination with some S-glass this Summer ! Maybe try some thin colored E-glass also.

Jim

Mp214parks · Mar 16, 2019

Thanks for all those links Jim. I’ve got some reading to do.

Mp214parks · Mar 16, 2019

Hi Francis.

Im a couple steps ahead of you with a similar goal. I chose to build a cedar mold. It took forever to get it perfect. But I wanted to have the option to build more boats from it. And since we are both racing, you want a perfect hull. I tried using foam strips first for the mold. They weren’t nearly rigid enough. I also just finished a prospector style canoe with a buddy. We put foam strips into our layup. We were working inside to out on a male mold. So one layer fabric, then foam strips, then more fabric. The idea was to fair the strips before proceeding. But for various reasons it didnt get faired perfectly. He is happy with it since it’s just a moose hunting rig., but I certainly wouldn’t recommend that particular process for a racing canoe. I chose (unless I’m convinced otherwise) to do my fabric layup then flip the canoe over and install foam ribs/floor as needed.

Guest · Mar 16, 2019

Francis said:
I'm Francis from Belgium and a ultra-marathon canoe racer (5 x Yukon River Quest). Next year, I want to participate in a race in the UK with 78 portages, so I want to build a C1 canoe (see picture) as light as possible. I built already 2 strippers, but the question is now, again in WRC or in composite.

Francis, this is some interesting and impressive stuff, and I am eager to follow your newest UL build.

I have not done 78 portages in the last 10 years combined. How many inviting pubs does one pass by during 78 portages in the UK? “McCrea, M. DNF”

Do you have a link to information on the UK race?

recped · Mar 16, 2019

I think it's this one......the portages are short and mostly paved I would imagine. There is likely a pub at every one of them!

https://en.wikipedia.org/wiki/Devizes_to_Westminster_International_Canoe_Marathon

Francis · Jul 15, 2019

2 week ago I've started to build my racing C1. I have chosen to make the core with 7 mm M80 Corecell, stripped on a male mold. The Corecell is easy to cut and you make the strips as wide as the shape of the canoe allows it. Glueing the strips together with PU glue (not so nice at the fingers as wood glue), but very fast curing (10 min.) The advantage of the PU is, it has the same hardness as the foam, so sanding was a pleasure.
For the in and the outside I go for 200 gr. Plain Weave Carbon. After a long search I found the fabric in 152 cm wide, so I can cover in 1 time the outside. For the inside, I think it's easier to work with pieces of 1 meter wide, laying from gunnel to gunnel.
It's the first time I'm gonna work with carbon so a little bit nervous. They recommend to work from the bottom to the top, so first wet-out a part of the Corecell with epoxy and then lay the fabric and apply extra epoxy to saturate the fabric. We will see... but still some questions:
Is it a good idea to cover the fabric with peel ply, so I can see ifthe fabric is complete saturate and maybe also easier to work with the squeezee?
For the gunwales I thought to glue 2 strips of 7 mm together and then cover it with carbon, but I read here on the forum that fiberglass is maybe a better option. Any idea how heavy I must go in the fabric and can I get the same stiffness as carbon? To make the thwarts, I had the same idea.

stripperguy · Jul 15, 2019

Francis,
I'm a bit jealous...Looks like you're well on your way to a light, strong hull.
Did you also glue the Corecell to the molds? Or only to the other Corecell parts?

As for the carbon, remember that carbon fiber is extremely poor in abrasion resistance. Think No. 2 pencil (do you have those?). The carbon will very quickly abrade if scrubbed against ANY material harder than it. Repeated beach landings will wear through the carbon fiber instantly...OK, not instantly, but it will seem that way.
And again, the best attribute of carbon fiber is the tensile strength. Cloth on the outside of a hull most often is in compression. Putting the carbon on the inside of the hull allows the carbon to perform at it's best, presenting its superior strength while avoiding its major weakness, abrasion.
Fiberglass on the outside will provide better abrasion resistance and adequate strength. After all, it worked for your other builds, right?

Jim Dodd · Jul 15, 2019

I'm confused by your method ! ( That doesn't take much !)

Are you planning on making a Male mold, or are going to epoxy the cloth to the Core mat ?

Carbon is difficult to tell if it is wetted. The peel ply might help, but I would try a large test sample first, using the peel ply !

I'm in the process of building a White Water composite. What I'm hearing is two layers Kevlar (5 oz) Kevlar inside. Outside two S-glass layers (6 oz) each.. Pull off the mold, and add partials to obtain desired stiffness.

My process is quite different than yours.

Jim

Francis · Jul 16, 2019

The Corecel is the 'core' of the canoe, sandwiched between 2 layers carbon. I've stapled the foam to the molds to hold it on place. An advantage of the Corecell is, with thermoforming you can shape the strips., I did it with a heatgun, but for wider pieces is it not ideal. If you have to deform bigger pieces, then you can put the Corecell in a big plastic bag and you can hold it in a DIY warm water bath. Maybe for a next build I'm gonna try this method.
Before I laminate the outside of the canoe, I'm gonna reinforce the bow, stern and the 'wings' with bias carbon cloth to have some extra protection in these places. I didn't decide yet to add an extra layer of fiberglass on the bottom, because I want to keep the canoe as light as possible. What is the weight and type of glass do you recommend to do that? My last stripper was made with 4 oz S-glass and it was nice to work with.
About the gunwales: is it a good idea if I first glue the thwarts to the boat and then between these glue the gunwale pieces, or first the gunwales over the total length of the boat and then the thwarts? Can I first laminate the gunwale when it's separate and then epoxy to the boat, but how can I then make the curve at the bow?
I hesitate if I will try the vacuum technique for the inside...

Francis · Jul 16, 2019

What's the best way to wet-out the carbon: brush, roller, sqeegee,...?
Is the use of peel ply waste of money if you don't apply an extra layer of fabric? For the moment, I don't know if it's also necessary to give a fill coat after the wet-out or can I directly go for a 2K clear coat? It's difficult to find reviews where they recommend a good product to do this job.

Alan Gage · Jul 16, 2019

For how you intend to use this boat I think you'd probably be fine without adding a full layer of fiberglass to the outside, although if it was me I'd at least add it to the stems and wings tips.

For me I've found the best way to apply carbon (and any other cloth) is to drape it over the hull and wet it out heavily with a roller and squeegee. I use a squeegee for the bottom of the boat because it's fastest and switch to the roller for the sides. After applying the epoxy heavy I come back with the squeegee and take off the excess.

Like others here I've starved carbon cloth before. To save time I've tried to wet out multiple layers of carbon and kevlar with poor success. Not that it can't be done but it gets tricky and it's time consuming so you have to worry about the epoxy starting to set before you're ready.

For adding a second layer I think it's best to wait 12 hours or so until the first layer isn't sticky anymore but it won't be fully cured so you'll get a good chemical bond with no sanding required. But if your second layer is just small fiberglass reinforcements I'd probably do them at the same time as the main layer. The four ounce s-glass you used previously would work fine for this.

It's very difficult to peel ply an entire hull, especially one shaped like yours. It won't be perfect and will probably need to be multiple pieces with relief cuts made where there are compound curves or sharp corners. Most of the hull should come away with a smooth finish but patches will still need fill coats.

The benefit of peel ply is that it essentially fills the weave. Rather than having to come back for 3 more coats of epoxy to do so, which you'll certainly need, you can usually get by with just one. For me personally I decided it's simpler to omit the peel ply on the main layer and just do the fill coats. If you're adding extra reinforcements (on top of the main layer) at the stems and wings then I'd definitely peel ply those areas to blend the edges in for less sanding/scraping later.

I think gunwales should be installed full length and then the thwarts added after.

Looks great so far!

Alan

Building racing canoe: WRC or Composite?

Francis

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