Carbon Copy Kite

[stripperguy]

Disclaimer: This build is Alan and Jim's fault!
If not for their pioneering composite builds, I would never have had the intestinal fortitude to attempt such an effort. I'm proud to sit on the shoulders of these giants...


Some of you here may know that I built a "Kite". That was a 14' 10" J Winters designed solo open canoe, for combined whitewater and flatwater use. It was cedar strip built, with glass inside and out. It's a little slow on the flatwaters, but very comfortable in heavier waters. Generally speaking, it's an excellent compromise.
While I was (and still am) mostly satisfied with the performance of the hull, at 39 lbs, it's just too heavy for me. I paddle the ADK's almost exclusively, and have carried as much as 5 miles at a time, with a full pack. My favorite paddling involves multiple carries between waters seldom visited, usually a bushwhack with boat overhead. Here's a look at it.
View attachment SyEhXyTm_gcn481VrPMyrLfqYv-byFT-V_dUY94OclvKE_NTV_QAWtcCCaM29CrmuGiT6yJvvY8UK4139X7ugwZE5VwqZZqyN-gs



So why not use my Kite as a plug, and make a lighter weight version?

Back in October of 2015, Soller Composites put their 5.9 oz 50" carbon fiber cloth on sale, for a little less than $20/yd. That's actually less than I would spend on cedar, so I bought a bunch. Well, that stuff hung around the shop, until I had some time to put it to use recently.

The plan:
Use my Kite as a plug to build a lighter weight version
Coat the Kite with mold release
Cover the Kite with 2 full layers of carbon and 2 full layers of 6 oz fiberglass, all saturated in epoxy resin.
Add gunnels, thwarts, and a seat to the carbon copy.
Carry, paddle, repeat as necessary.

 

[Muskrat]

Can't wait. I'm always ready for more one off composite builds. For mold release I'm still a fan of the window shrink film, and leave those stems open until after you pull it off the plug. What are you thinking for a core/ribs?

 

[wingnut]

Great idea for a lightweight boat. Interested to see how it turns out but my first thought is how would you get the composite shell off the mould. Great looking boat by the way.

 

[Muskrat]

Another question. What's your plan for the gunwales on the existing kite? Won't they get in the way when molding a new shell? If I remember from the original build they are not removable.

 

[stripperguy]

Mr Muskrat,

Yes, my carbon fiber over foam gunnels on the existing Kite will definitely get in the way, so I'll need to improvise to work around that issue. At the moment, all I want is a similar performing hull at a much lower weight. If I can't exactly replicate the original Kite, that's OK.
I expect I'll need some stiffening of the hull below the waterline, but this will not be an expedition capable boat, just something to make long carries easier for my 60 year old bones!! I can always add any necessary stiffening to the inside after the shell is off of the plug.

I did a small test patch using the same lamination schedule that I plan fot the hull, extrapolating that test patches density, I might end up with an initially wetted out shell weight of 14.5 lbs!! Of course, fill coats, and trim will surely add more weight, but if I could manage to keep the weight under 25 lbs, I'd be thrilled.

 

[Jim Dodd]

Lean more towards Alan than I ! He put us on to Soller, and their great price for carbon fiber !

I finished glassing my insert, just haven't taken pics yet. The hull is plenty stiff, as I added a full layer of 6 oz E-glass with no seal coat, and just one fill coat, on the insert part. I I'll weigh it soon. Alan and I weighed it on an old fish scale, before this last layer, and it was 26#. You have me beat already !!

My thoughts now, are to make another Carbon fiber, off of my First Carbon Fiber Nokomis. I'll be doing this Before adding my Outwhales to CF Nokomis.

I've been hesitant about using a release agent, but thanks to you, I'll give it a try !
Did you use Part-all ? Curious if it comes off your Kite OK ?

Nice Work !

For my ends, I just put three layers of Electricians tape, on the leading edge of the stems of my plug. Glassed over it like a regular hull. A day, after I glassed it, I cut through to the tape, and it released, with no problems. Once off the plug, I just epoxied the ends close again. I believe it was much easier. And will do it again.
Again Nice !

Jim

 

[stripperguy]

The first step would be to buy some mold release, a gallon of PVA from Fiberglast Industries. Oh, and make sure the mold release will actually work the way I expect it to.

So I dug around in the boat shop and found a left over bulkhead, that had been previously stripped, sanded and glassed on both sides.
I applied 2 coats of PVA to the panel, using a brush.
A day after the PVA was dry, I prepared to make a test patch, using the same lamination schedule that I plan for the carbon copy.

Here is the test patch on the leftover bulkhead.


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It had the 2 full layers of 5.9 oz carbon, and 2 full layers of 6 oz E-glass, wet out with RAKA epoxy resin. I think it measured around 3.5 inch x 6 inch.

I haven't worked with carbon much, so I was surprised that it was so difficult to see when the carbon was completely wetted out. Even so, the little test patch was done in a few minutes.

The next day, I peeled the test patch off of the leftover bulkhead, so far, so good. The test patch was tack free, but clearly the resin was not fully cured. That little test patch was very flexible, like a bendy tiger. But at least the PVA mold release did its job. Can you imagine if I got a carbon copy permanently stuck to the outside of my canoe!?

After a few more days, I noticed that the test patch really stiffened up.
So then my head starts racing...this can really work! I weighed the little test patch, determined its weight/sq in, and got even more excited! Granted, I did not fill the weave of the cloth, but if I applied a similar amount of cloth and resin to the entire carbon copy, the bare hull might weigh as little as 14.5 lbs!!

 

[stripperguy]

Time to get real!
Here's most of the supplies required, the PVA, the carbon fiber cloth, fiberglass cloth.


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I put 3 coats of PVA mold release on the kite, not wanting to take any chances of wrecking 2 boats at once.
At this point, the kite is just resting on a couple of sawhorses.
Next I draped 2 full layers of the carbon fiber cloth over the hull.

View attachment mOe_0-_J2dKB2jM5hO5_fbEUyVek0I6Cga03QL5Qq8p-2qOoRN2ROHMbqKLIkqb-0zYcP0ovdTAw5ZQLbPxj6CeZZlGrB489bPMu


You can probably see the potential problem already.
I'm already going to have an issue with the gunnels getting in the way.
And with the Kite on sawhorses, there's no way possible to get the carbon to stay close to the gunnels.

So I decided to make a quick and dirty strongback out of some leftover 2 x 10, and use a couple of temporarily clamped forms to hold the Kite.
Other than being a little too tall, holding the Kite on forms on a strongback works much better than having the boat dance around on sawhorses.

Later, I hope, I can use those same forms to hold the carbon copy shell.

Did I mention that I plan to leave the stems open, so I can stretch the carbon copy enough over the "crease" to get it free from its parent?


https://lh3.googleusercontent.com/0...B0mYSfL7uz-tfx-ZxrWh3XbbTlNK2Ug=w1410-h944-no

 

[stripperguy]

So here's the plug mounted on the forms on the quick and dirty strongback.
You can see I've draped the 2 layers of carbon cloth, but not trimmed the excess yet. Under that cloth, and on top of the plug, is 3 coats of PVA. I hope it's enough!


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Next, here's a view of the open stem. I've cut back the carbon to where it starts to deviate from the keel line, and slid a couple layers of wax paper in there to keep the sides separated.


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The carbon cloth is quite stiff, and I'm really concerned if it will conform to the entire profile of the plug.

 

[stripperguy]

Let's see, where was I? Oh yeah, time to wet out the carbon fiber.
I initially mixed 12 oz of RAKA epoxy, using their 127 thin resin and the 608 medium hardener. I'm using a 4 inch foam roller and a fresh plastic roller tray liner.
I'm working alone in my basement, which is fairly cool. So, hopefully, I'll have plenty of time to work without needing to rush.

Well, It's a good thing the epoxy is slow, as I needed about 1 1/2 hours to wet out the hull. Remember, this is just the 2 layers of carbon fiber cloth. It's darn near impossible to see when the carbon is fully wetted, and it doesn't like to be rushed. Once I had most of the shell wetted out (I think), I wrapped around underneath to do the crease, and sheer line. The plug (my Kite canoe) has the carbon fiber over foam gunnels, so these are in the way as it is.
Yup, it was just the nightmare I was fearing that it would be!!The carbon really didn't like that sharp crease, and it refused to adhere to the hull until it was thoroughly wetted for a long distance along the sheer line. My roller had trouble to tuck the cloth into the crease/sheer joint. Also, the roller constantly peeled the cloth up as I tried to stick the carbon along the crease and sheer. Eventually, I realized that I needed to roll up and down, very gently, rather than along the length of the hull.
Giving up hope of using the roller, I switched to a squeegee. I needed to squeegee the entire hull anyway, to remove any entrained air from the epoxy and to get the cloth to better conform to the plug. When I got around to the crease while using the squeegee, it actually worked much better than the roller.
Phew, it was a long 1 1/2 hours, and I likely stained my basement floor with all the palm sweat! I used a total of 40 ounces of epoxy when all was said and done.

Hopefully, I'll end up with a very lightweight, durable hull...hopefully.

Here's a look at the fully wetted out hull.


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And here's a look at that troublesome crease/sheer line.


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[stripperguy]

Here goes the next step in the lamination schedule.
As I had mentioned upthread, the RAKA epoxy is able to crosslink successive layers as long as the time between them is not excessive. Also, the clock is ticking on the carbon wet out, I don't want a full cure before I attempt to pry the shell off of the plug.

I draped both layers of 6 oz cloth, and wetted out both at once. I was expecting a cake walk, after all, I've been working glass and epoxy for a long time. Well, I still need to learn to manage my expectations!! Once again, I was surprised at how long it took to wet through both layers of cloth. But at least the glass conforms more readily to the carbon. This took another 40 or so ounces of epoxy and 2 hours to finish.

Here is the draped and partially trimmed glass.

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And here it is part way through the wet out.


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Lastly, here's a look at that pesky crease/sheer line. You can see that most of the crease has been replicated, but the sheer line (and site of the future gunnels) doesn't look so nice. I'll need to figure a way to make lemonade from the sheer line. Also, the crease is more fully replicated near the center of the hull, and less so as you approach the stems. My hope is that when I trim it all out, it will look as if that's part of the design.
Sooner than later, I need to pry the shell off of the plug. I hope!


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[Jim Dodd]

Glassing over the gunnels of my strippers has prevented me from making copies. I also glue mine gunnels on. A drawback for sure.

Yeah I didn't like wetting out the carbon fiber either, If it would change color like fiberglass cloth, that would solve the issue !

Were you happy with the texture of the E-glass ? Enough fill coats?

I did go with Raka's UV inhibited epoxy, hoping to protect the the hull. Time will tell !

Thanks for posting. Great pics !

Jim

 

[stripperguy]

Jim,
These gunnels are carbon and glass over foam, epoxied in place...they're not coming off any time soon!!
I have yet to add my fill coats, only one stem partially closed for now, but I'm jumping out of sequence.
More to come until I catch this thread up to real life. By that time, I'll be on a family trip to Florida for two weeks, so not much more will happen until mid February.

 

[Alan Gage]

Good stuff. I wondered how you were going to deal with those gunwales on the mold. I'm very interested to see how it looks once removed from the mold. I don't envy you having to work around that.

Working with carbon and kevlar certainly is different than fiberglass. I feel pretty comfortable with it now but it sure would be nice to have a better visual when wetting it out.

When I made my composite canoes from a male mold I put a line of tape along the shear so that just in case the hull wanted to stick to the mold I'd at least have easy separation at the shear so that I could slide tools up there to aid in breaking it loose. Thankfully that didn't turn out to be an issue.

I found a rubber mallet came in handy for breaking the bond between mold and canoe. You could hear it SNAP as you whopped the hull and the bond was broken. Did this multiple times over the whole hull, sometimes hitting pretty hard. The woodstrip mold was still on forms so I removed most of them so that the hull would have more flex and separate better when hit.

I like Jim's idea of fully wrapping the stems at the time of layup and then cutting them open while the fabric is still green. Sounds clean and easy.

Alan

 

[Alan Gage]

BTW, I'm pretty sure you must have done something wrong with your layup. There aren't near enough epoxy drips and puddles on the floor.

Alan

 

[stripperguy]

OK, time to pop the shell off of the plug...drum roll please!
I expected that the poorly replicated sheer line and crease would peel away from the plug effortlessly. Ha! It barely moved when I tugged on it. Alright, I'll admit that my grip strength hasn't fully rebounded since the carpal tunnel surgeries a month ago, but c'mon. I eventually discovered that the areas nearest the open stems were easiest to begin with. I accidentally peeled too far and started to delaminate some of the glass. Duly noted, I proceeded with more caution. I gradually managed to get most of the sheer line free, but the thought of the entire shell getting stuck was moving from nightmare to reality.

Uhmmm, I then decided to use something soft, that I could wedge in between the shell and the plug. So I went out to the boat shop, and retrieved an ever present left over cedar strip. A quick minute on the belt sander gave me a suitable soft chisel.


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I spent the next 40 minutes alternately hammering in the soft chisel and prying it free. I now had the shell loose up to the bilge. Next, I very carefully used my gloved, aching hand and a wonder bar to loosen the shell all the way to the waterline. By now, I could creep both gloved hands up into the space between.

I do have a short video, let's see if I can link it.

Link to video of release

My buddy hickoryskier (from another forum and a life long friend) dropped by, and helped me to lift the shell off of the plug, lift the plug off of the forms, then place the shell on the forms to keep it from sagging.

Oh, I also weighed the shell. Remember way back in the beginning of this thread, I had hopes of the shell weighing 14.5 lbs at this point? Well, it doesn't. It weighs 16.6 lbs. At least I don't have to throw it away. And even though it was pretty tough to get it to pop free, it did come off without any damage to the shell or plug.

Phew!

The rest will be relatively easy...trim back the stems, add carbon and glass to close up the stems. Add some epoxy fill coats to the outside, flip it over and add gunnels, thwarts and a seat. Maybe, maybe add some sort of bulkheads, but no decks. The shell right now is still a little flexible, but the crease is the crease, there's no altering it now. It's that stiff. If the shell proves too flexible once I can test paddle it, it will be a simple matter to add some reinforcement to the inside.

I have about 6 hours invested so far. All of the hard stuff is out of the way. Once I seal up the stems, I'll drag the carbon copy out to the boat shop to trim the sheer line. I don't want to make too much of a mess in the basement.

Alan,
MDB warned me about making a mess in the basement, we're preparing to sell the house soonly and want top dollar, so I was very, very careful with the resin. I usually have a ghostly outline on the floor that remains for years and years!

And yeah, the carbon is quite different. For me, the biggest challenge is the lack of any clear visual indication of when the cloth is actually wet out. Really hard to tell.

Oh, it's now been 10 days since I popped it free and there is no sagging, the shell looks amazingly uniform. All of the challenging stuff is behind me, I think. I have one stem partially closed and the other remains open for the moment. We have a family trip to FL coming up, so not much more will get done for a while...

 

[stripperguy]

OK,
I made a little progress on the carbon copy.
Just before I left for Va, I had trimmed the stems back, and closed the one stem using some carbon scraps cut on a 45 degree bias.

Here's a look at that stem

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I wasn't at all pleased with the results...the stem on this hull is designed to be rather blunt, but this was looking like an anvil!!
So I decided to epoxy on some foam to provide some material to form a better profile. Had to shave and hollow some parts of a foam filler piece to fit the changing (erratic is more like it) cross sectional profile.

I toyed with the idea of treating the other stem the same, carbon fiber closure first, then foam, but thought better of it. I added some foam to the other stem too.
After the epoxy (with added Cabosil) cures, I'll shape both ends to a pleasing profile and add more carbon fiber, and glass. The one stem will have a carbon sandwich, the other end I'll need to add a layer of carbon on the inside, to also have a carbon sandwich.

Here's how the stems look now, ugly for the moment, but easily shaped later.

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And here's the other end

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Lastly, here's a overall view

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[Alan Gage]

That looked pretty intense getting the hull to release. Even though I knew it released cleanly I was cringing as I watched it flex, flex, flex, and finally POP! It was those areas where I found the rubber mallet came in handy. And, like you, I remember using a scrap strip of cedar as a wedge. Thankfully for me I didn't have a tumblehomed hull so I could shove that strip up there a long ways to break the bond. Connecting the air blower to the compressor was a help too. I don't remember that it actually helped the hull release but when blowing compressed air up the crack at the shear I could see the shell lift and flex where it was released from the hull. This helped me pin down the sticky spots.

I'm a little uneasy about those foam stems but I tend to accidentally run into a lot of rocks. How many layers of cloth will you put over them? Finding a tidy way to close the stems is tough.

Will you be doing carbon over foam gunwales again? Carbon thwarts? Carbon seat?

Maybe I missed it but do you have a target weight for the finished product? So far it's looking like sub-30 pounds should be doable. I'm really curious to see what you think of the stiffness of your hull at this point. I needed a lot more layers of cloth (9-10) until I was satisfied with the bottom stiffness but you're working with a more rounded hull and aren't designing it to take as much abuse.

Alan

 

[Jim Dodd]

The video was eye opening ! I think I will address my male plug with plastic, up to about the 1" waterline on my next build ! And then Partal for everything else.

I didn't have trouble with my hull releasing from the mold, with the plastic film, just had a hard time getting the cloth to follow the tumblehome.

I'm with Alan on the foam. I tried making a foam form for the inside of my first Kevlar. I shaped it, which was easy, then wrapped it with wetted cloth. Pushed It from the inside of the hull, out ! It extended about an inch beyond the hull. When the resin set, I pulled the foam form back out.

It was ugly, and made a good excuse to use Kevlar felt, on the outside.

Enjoying this build immensely !

Thanks !

Jim

 

[stripperguy]

Jim,
I just looked back and realized that I never answered your question about Part-All...I used PVA from Fiberglast Industries, no wax, no plastic.
Oh that release video was dramatic, wasn't it??!! It wouldn't have been so bad, but I had carpal tunnel surgery on both hands about a month before, so I don't have the grip strength or flexibility that could've made for an easier time of it.

Now, on to the foam.
On the plug, the cedar stripped Kite, I made carbon fiber over foam gunnels. I initially had just a single layer of bias woven carbon, but that wasn't strong enough to survive cartopping without permanent deformations. So I added a layer of glass tape, was it 6 oz? I'll have to go back and check. Anyway, that added layer of glass has so far proven to be adequate. When I tie my Kite down to the roof racks, I don't have anything between the gunnels and the Thule load bars. I use 1" nylon straps with Ancra buckles and put about 100 lb preload on the looped straps. Looking at the gunnel profile and the actual contact patch with the load bar, I'd say there is over 1,000 psi contact stress.

By the time I shape the foam at the stems, I'll have a similar cross section as the Kite's gunnels. But, but, I'll eventually have 2 layers of carbon with 2 layers of glass on the outside, and 2 layers of carbon on the inside. Probably gonna have some Dynel too, just because I'm too lazy when I launch and land.
I'm fairly confident that the stems will be adequate.

Now on to Alan's questions...
Some of the hull is already incredibly stiff, that crease in particular, and the bilge as well. Center of the hull currently can flex readily, I haven't yet decided how I'll stiffen that area. No offense to you Jim, but I don't want to use strips as a core. I do still have some Divinyl foam from DIAB, I think it was their 4 lb/ft^3 stuff.
Or maybe just a few more layers of carbon in selected areas.
And I do plan for carbon wrapped gunnels, undecided on the substrate. I did like your cedar substrate carbon wrapped gunnels. Thwarts and seat supports will definitely be carbon over foam, and I have a carbon fiber tractor seat from some guy in Iowa or Illinois or some other I state!
Target weight? Yeah, I'd be thrilled if it comes in under 25 lbs. Again, it's not planned to be an expedition worthy build, just something to ease the burden of a 3 mile carry with a full pack.