Carbon Copy Kite

[stripperguy]

A little more progress...
I clamped a left over cedar strip to the carbon copy sheer line and scribed a trim line. Then I used my Roto-Zip to make lots of dust and trim the excess sheer. The sheer is maybe 70% OK, but definitely has its problems. In a few spots, it's pretty darn wavy and I've been struggling with ideas to salvage the mess.

Here's a look at the trimmed shell

I know, it looks bad, doesn't it?
But wait, it gets worse, here is a look at the waviest portion of the sheer

All of the shell has really firmed up, I can tweak the overall shape slightly (must be careful to not screw up the rocker) but that sheer line may as well be cut from stone.
All is not lost, though. I think I can cut some slightly oversized foam for the gunnels. Then sand the gunnels to a smooth profile, essentially ignoring the wavy sheer partially encased in them.

Here's a look at some left over foam sections stuck on the sheer for illustrative purposes.

Sure, it's got some wiggles (foam is only resting there unsecured except for gravity and friction) but even at that width, I would have plenty of stock to work with to straighten things out. The worst portion of the sheer would be forever encased inside the gunnels, although there would still some waviness left exposed. For a first effort, and maybe a sub 25 lb build, I can live with that!

So that's the plan:
Carbon over foam bottom stiffening
A little oversized gunnels section to mask to lousy sheer
All carbon over foam gunnels, thwarts and seat frame

Oh, and for those of you keeping track, or at least wondering, I have 13 hours invested so far.

 

[Cruiser]

This is an inspiring thread, I have been following along ... between Jim, Alan and you, I am planning on expanding my next solo build to include a "copy".

I have a lot of daydreaming yet to get to the build start ( as well a few projects), but I am thinking early spring. I have also been planning on ways to lighten the wood build part.

I wanted to run some tests before I actually use this idea, but you are on the gunnel part and it may or may not seem useful to you, so I will share and get comments now.

On my Freedom solo build I used 3/4" cherry uniwales which worked out really well and saved a lot of build weight. They looked like this:



My thought was to use 3/4" cedar gunnels (rounded over with 1/4" radius), cover them with carbon fiber sleeve, use the shrink sleeving to get rid of excess epoxy and get a good finish. Let cure and cut a channel down the center for installation. Installation is just taping off the sheer (just down from were the gunnel will sit, just to save some mess) wetting both sides, wet the channel then pack the channel with thickened epoxy. Wipe off excess to make a nice fillet.

In your case, you could size the channel to fit and straighten those waves some ... I am hoping this would be a straight forward and easy method ... I won't know until spring when I do some strength/weight/flex/stiffness testing this spring.

Your build is inspiring ... Alan and Jim I am learning from all of you

Brian

 

[wingnut]

Cruiser, How did you mount grab handles and thwart with so little to work with on the gunnel. I like the idea of a uniwale but have yet to figure out the mounting problem.

 

[stripperguy]

Brian,
in this thread, http://www.canoetripping.net/forums...scussions/diy/848-j-winters-kite-build/page11
and page 12 I did some comparative strength tests of carbon fiber gunnels.
The best way to reduce the weight penalty of wood trim, is to eliminate it! Just my humble opinion...
It's tough to get lighter than foam under carbon.
I ruminated for almost 2 years before I had the time to do this build.

 

[Jim Dodd]

Stripperguy

I too have the shearline waves. They seem to be just above where the tumblehome runs out.

I'm using Ash(I know heavy) but I'm going to install the inwhale, before I make another copy. Hopefully this will straighten out my shear !!!

I believe Brian may have a good solution. Wrapping the foam gunnel with carbon fiber sleeves, or as Alan did on his "Barrens Build" do a search. I believe page 7 . Alan wrapped his gunnels with bias woven 4"carbon fiber. From Soller. He just wet it out with a brush, and the bias weave, conformed to the gunnel quite nicely.

In Stripperguys case, maybe wrap your foam gunnel first. Off the hull, I'd try and bend the foam pretty close to the Kite shear shape. After the epoxy cured, I'd cut an 1/8" channel for the hull shear to fit in. This should force those wrinkles out, in my thinking anyway. No Guarantees.
I do see merit in Brian's idea !

Jim

 

[Cruiser]

My thought process for cedar is this:

- cedar is less than 1/2 the weight of cherry ( even less for most other hardwoods)
- cutting the channel reduces the cedar further (there is a lot of the wood removed)
- in my tests I plan to use the cherry strength as the "goal" ... it works for me so far, so it can be considered the minimum. I will make several layups with carbon, I am hoping it is stronger so I can reduce the size and save even more weight. I agree foam is lighter, but when I modeled this, there wasn't much wood left so those weight differences tend to get minimized. Being honest, I don't have foam, have no experience with it, I tend to think of it as a bit flimsy, hard to "recarve" to a new shape and have it look uniform and good ... sooo ... i tend to stick with what I know, I can shape and form cedar easily and the like I said, I don't think there is enough weight savings to warrant the new skill set. If you want, I can sub the numbers for foam and compare the weight saving of foam over cedar .... just post the density of the foam and I can do it up easily.
- the wood base gives a solid base to apply the carbon fiber tube, easing resin removal, tube stretching and shrink wrap application, to give a lighter layup
- I have lots of white cedar (akin to Jim having lots of ash ... what you have influences what you use, lol)
- I hope the solid wood base/shrink wrap will give a uniform finish that is almost ready for varnish, so a lot less sanding to make it look good
- with a wood base, I suspect the look will be a lot more even, less wiggles/curves etc
- for these gunnels, I intended to lay them up using the canoe mold to pickup the shape of the gunnels, I think it would be best to have the carbon versions close to the right shape to start with

Mounting is a bit more to personal tastes, my last build I decided to address an issue that sometimes plaques me on trips. . that is trying to slide my gear under the yoke and thwart only to find I am short an inch or so in depth and then have to "finigle" things to fit. So on this build I mounted to the top and not the bottom, like this:



It made more sense for the yoke to be done this way, considering that now the load is transferred from the yoke directly to the gunnel, taking the stress off the fasteners. Using this ideal, it should be simple to just angle the fasteners to run through the gunnels at an angle, instead of the traditional vertical. For transport, it is pretty easy to move the canoe back or forward to avoid the racks ... I will know how well this works this coming tripping season.

I am enjoying the discussion, different perspectives lets me leverage all the experience here.

Brian

 

[Cruiser]

I also looked at your previous work and that was very enlightening ... you refer to foam, but I didn't see any "branding" on what type you used. You have me thinking to also model a foam piece in my trials ...

So, what type of foam are you using?

Brian

 

[stripperguy]

I also looked at your previous work and that was very enlightening ... you refer to foam, but I didn't see any "branding" on what type you used. You have me thinking to also model a foam piece in my trials ...

So, what type of foam are you using?

Brian

Brian,

I have some left over Divinylcell from DIAB, I think it was their 4 lb/ft^3 stuff. I'll be buying some 1/8 sheet from them for the bottom stiffening.
My preferred paddling spots differ from most folks...think more like bushwhacking with a canoe overhead, kind of like what Conk does. I don't do long expedition type trips, and some carries are in excess of 2 miles, sometimes with no trail, not even a game trail to follow. All of this influences my design and lamination schedules, and even the sort of trim I choose.
I've been very happy with the foam substrates, very easy to work with.

 

[Cruiser]

I haven't used foam before and started looking up suppliers in Canada ... am I just looking at the wrong suppliers or is this stuff just plain expensive.

I am assuming you use solid sheet and cut it up ....


Brian

 

[stripperguy]

I haven't used foam before and started looking up suppliers in Canada ... am I just looking at the wrong suppliers or is this stuff just plain expensive.

I am assuming you use solid sheet and cut it up ....


Brian

Brian,
The 1/8" sheet I'll need for bottom stiffening is $50, probably enough for 2 hulls.
I also have the remnants of a 2" thick x 4' x 8' sheet that I received as a sample direct from DIAB. Shamefully, I pulled rank to sample the material while I was still working in my R & D company. It didn't work out for the application I needed it for, but I used the left overs for several years on other projects, including stuff at home.

 

[stripperguy]

I think I have a way to make lemonade out of those wavy sheer lines.
I cut the worst of the wavy sections 3/8 inch lower, that eliminated about 75% of the waviness. The balance of the wiggles will now easily sand out when I profile the foam. No time tonight to epoxy the foam in place...I'll be gone for nearly 2 weeks starting tomorrow.

Here's a look at the Divinylcell foam in place. I tried to show the sheer line at its worst.

The overhanging gunnels at the stems will probably be trimmed back after they're epoxied in place, and another block epoxied at the ends to fill in the underside of the gunnel overhang. As much as I would like to profile the gunnels and wrap them in carbon sleeving before I install them, those wavy sections of the sheer would transmit right through. The only way I can see to have a uniform gunnel profile is to sand the foam once it's in place.

So now, a question for Alan, Jim, Muskrat, et al;

Well, first a statement. I previously used some bias woven 4" wide carbon fiber tape to laminate the foam gunnels on the cedar stripped Kite. That laid in place nicely, and no stray fiber at the edges. Nice, but pretty pricey. I would prefer to spend less and try using some straight woven carbon tape.

Have any of you used straight woven carbon tape for the gunnels? I think the curves are mild enough to allow a wrinkle free laminate, but I'm not sure.

 

[Jim Dodd]

To my knowledge, Alan has much more experience than I, on this. I believe he is off hiking in a warmer climate right now. I did see his latest build in person. He really liked the 4" Bias ply carbon, it conformed nicely. That tells me, that the regular woven wasn't a winner, or he would have used it.

I would try a piece of regular woven on some scrap, with a similar shape to the foam gunnel. That should answer your question.

Your gunnels do look better, and I'd think you could shape them to eliminate the kinks.

Lookin good !

Jim

 

[stripperguy]

Thanks, Jim. Trimming down the wiggly sheer really paid off! The waviness that remains can be readily sanded to a smooth profile.
I actually forgot that I partially wrapped the stripped Kite gunnels with fiberglass tape, over the bias woven carbon. I don't recall any catastrophes when I did that, so at least a partial length wrap would be OK. As I type, I'm also thinking (I do that sometimes) that I don't necessarily need a continuous carbon wrap on the gunnels. I could do a 3 piece wrap, kind of like the way you and Alan glass your insides. Or was that Mem? Too many guys to keep straight.

I think you're right about a test piece though, that's the best way to determine if somethings is a go or not.
I need to look through my stockpiles, I thought I bought 50 yards of 4" fiberglass tape...maybe 9 oz or so?

 

[Muskrat]

I can't help you except that I'd think the gunwale to hull should be rounded over as much as possible. That's where I'd think the most problem would come from. I've got some heavy carbon tape (12k?) and some 6 oz glass tape somewhere, both 6" or 8" wide. I can send you some scrap in the mail for testing if you want to try it before buying.

 

[stripperguy]

Mr. Muskrat,
Thanks for the offer...somewhere in my stashes I have some 4" wide 9 oz glass tape, just need to find it!

 

[Jim Dodd]

Here's a couple of pics

Jim of a test scrap, I did last week.
Not a good one but ? The wood is 3/8" thick. I wet out a small piece of regular woven CF. It wouldn't follow the sharp edge of the wood, but it should give you an idea of the kind of radius it will follow.

Jim

 

[Alan Gage]

Have any of you used straight woven carbon tape for the gunnels? I think the curves are mild enough to allow a wrinkle free laminate, but I'm not sure.

My advice is stick with bias woven tape. Plain woven fiberglass is probably pliable enough to do the job but carbon is too thick and stiff. Same goes for kevlar tape. I've used plain woven carbon tape twice for gunwales: once when I vacuum bagged and once on my failed infusion. Without the pressure from the bag the plain woven tape did not want to conform properly and kept wanting to peel from the hull and bridge the transition. It was better when wet out together with a top layer of fiberglass tape but still not perfect. The bias woven stuff conformed no problem. The only tricky part, as you know, is trying to keep a straight edge. I fixed that problem by deciding I didn't care.

Alan

 

[stripperguy]

Alan,
Thanks for the input...I looked at the final cost differential between straight woven and bias woven carbon tape. In the overall scheme of things, it's really only a few dollars. I guess I shouldn't be such a cheapskate!
So the next steps will be ordering the 1/8" Divinycell for the bottom stiffening and the bias woven tape for the gunnels.

 

[stripperguy]

so...it's been a while.
Since my last post I've:

1. Added to that pile of window air conditioners that sneak into the photos
2. Ordered and received 4 inch wide bias woven carbon fiber tape for the gunnels
3. Found my roll of 9 oz, 4 inch wide fiberglass tape for the gunnels
4. Ordered a 4 ft x 8 ft sheet of 1/8 inch thick Divinycell for bottom stiffening
5. Spent a week and a half in Florida while missing the best powder skiing in two years.
6. Washed away all traces of the PVA release film from the inside of the shell
7. Even had time to take the Bonnie for a spin, first motorcycle ride since last year!

Today's record warmth was just the ticket to drag the shell outside and scrub away the stuck on PVA release film. I was trying to use a rag and bucket, and that just wasn't doing the job. So I dug out a garden hose, turned on my outside water line, and scrubbed and rinsed until the inside was ready for some stiffening foam, resin and a little more cloth.

While I had the shell outside, I took the opportunity to snap a few photos, in the basement (or boat shop ) I can't get far enough away to gain the proper perspective.

Here's the shell, with sporadic patches of PVA still stuck inside, and the ready for epoxying foam gunnels sitting on the wavy sheer line.

But here is another view, better showing the warts and all...I should be able to smoothly profile the foam gunnels before applying the carbon and glass tapes.

Here's the business side, which is all that I care about. In fact, other than a Dynel wear patch and some paint, the outside is as done as it's gonna get!!
I'll worry about aesthetics on the next boat.

 

[Sven]

The wiggly sheer is caused by the gunwales on the plug? Doesn't matter in terms of how it will handle? Function before form right? I personally think carbon looks sexy. As long as you can stay close to your goal on weight, not a big deal...