Carbon Copy Kite

[stripperguy]

Added foam rails to the bottom of the Alan Gage carbon seat.
Added Cabosil thickened epoxy fillets on the foam/seat interfaces.
Used 6 oz glass to wrap and reinforce the foam seat rails.
Thwarts are done. Center thwart has 2 layers of carbon/kevlar sleeve over 5 lb/cu inch Divinycell.
Short thwarts have 1 layer of carbon/kevlar and 1 layer of borrowed from my S-I-L carbon over the same foam.
Epoxied and filleted in placed, but not before sliding a pair of short sleeves over the thwarts.
Wet out the short sleeves to reinforce the thwart/gunnel interface.

Still need to fabricate the seat pedestals.
I won't locate the pedestals until I test paddle the hull and find the right spot for the seat.
That might be Sunday or Monday.

Until then, here is a photo history of all that I've described above.

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View attachment J6mFVBUNmlc3Ntgjym3Oop6_itn7A4KOBXUVVJZ2cbn6NkXXUnsmHE28RLse1vY5HVRok08KVLq58aN0fA36fC0CIQOequsRFN83


View attachment aJpfZWYAWv5r8SClmpLQx7Y9dP4JiGd2vDhJhkTkK_5Zkk-r6nC3OSR_LyGN2aKkKrHz0kc4ix5S-juP5C3LCHwp1OrG2ns84Nd-


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[stripperguy]

Oh, almost forgot...
I weighed the boat just as you see it above (minus the tub of Cabosil)
Still need to add the weight of the carbon/foam seat pedestals, but so far it's 27.5 lbs.

 

[Canotrouge]

With the seat pedestal, and the foot brace(I assume you will have one) you won't be much over 30#....

 

[stripperguy]

With the seat pedestal, and the foot brace(I assume you will have one) you won't be much over 30#....

The 3 thwarts and the 3 oz of resin I mixed to wet out the short sleeves added 0.5 lbs. The 2 carbon fiber over foam seat pedestals might weigh 1 lb, we'll see.
I guess I'm more surprised than disappointed with the final weight, I will have missed my goal by 12%...
On the plus side, I've enjoyed this method, and learned a lot, and this boat will be roughly 2/3 of the weight of it's big brother, and that's not all bad.
I better understand the challenges of an all composite build, and the advantages/disadvantages of carbon cloth.
I'm a firm believer in Divinycell now, as if I wasn't before!

Overall, I'd rate this build as an 8.5 out of 10, not bad for a practice build, but I'll need to rate it again after I've had the boat on my shoulders for a few miles.

 

[Jim Dodd]

On the plus side, I've enjoyed this method, and learned a lot, and this boat will be roughly 2/3 of the weight of it's big brother, and that's not all bad.
I better understand the challenges of an all composite build, and the advantages/disadvantages of carbon cloth.
I'm a firm believer in Divinycell now, as if I wasn't before!

Overall, I'd rate this build as an 8.5 out of 10, not bad for a practice build, but I'll need to rate it again after I've had the boat on my shoulders for a few miles.

This has been an AWESOME thread.
This composite thing has been a new light in my life !
Thanks for sharing !

Jim

 

[latremorej]

Nice! So 30lbs is obtainable!

In the meantime. Tare out the scale with that tub of cabosil and then check the weight, lol, it's carbon fiber... nobody will question it! Hahahahaha. Thanks for sharing all of this!

Jason

 

[deerfly]

another excellent build thread, you and Jim D are killing it.

I'd say you did pretty dang good on the weight too, esp since you're not vacuum bagging or using peel ply.

 

[stripperguy]

Today is the day! I Took the carbon copy Kite to the Mohawk River and gave it a test paddle to see where I should put the seat pedestals.
As it happens, we had a delivery this morning of a custom glass shower door. It was crated with some 2 by's and closed cell foam glued to the inside.
So I used the parts of the shipping crate to make a temporary seat pedestal. The foam sits against the hull, protecting it from the 2 by's and prevents the whole mess from sliding around.

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And I was concerned that I might have put the center (almost center? central?) thwart in the wrong end. It's really hard to keep track of bow and stern, so I dragged out the red Kite for a side by side.

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It was still hard to tell, so I grabbed a couple forms, and phew, I had it correct!
A while later, after MDB baked me some birthday peanut butter cookies, I loaded the carbon copy on the racks and drove 8 minutes to the Mohawk River, at Lock 7.

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Fiddled around with the seat location while MDB watched to see if I was trimmed out or not.

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I suppose I should be excited, but the carbon copy handles like, uhmmm, a carbon copy of the original! I guess it's doing what it should.
Satisfied that the seat placement will be OK, I brought the boat back home. Time to build up the seat pedestals and finish the portage thwart that I started last year.


Oh, and I finished the first foam/E-glass test patch. 2 full layers of 6 oz on each side of 1/8" H80 Divinycell foam. It weighs 1-1/2 times more than the carbon/E-glass test patch, but is incredibly stiff. Looking back on this thread, I see the shell gained 6 lbs when I added the foam stiffening and carbon overlay.
Almost the same, advantage still for the carbon. I plan to make a few more test panels with varying weights of glass and different number of layers.
I'll also model the various laminates in Inventor, using real engineering properties, so I can close the loop on these test panels.
I'm fairly sure that I can produce a better hull using foam and glass exclusively. We'll see...

 

[wingnut]

Curious to see what you come up with on your foam and glass test panels. Do you think the foam will be quite a bit lighter than a cedar core of 3/16". I think the foam by itself would be somewhat lighter but if it soaks up resin it's hard for me to guess what it would end up weighing.

 

[Jim Dodd]

Yup That's a carbon Copy !

It doesn't surprise me, that they handle the same. The big difference comes at the portage.

I weighed the trim and seats for Vader at very close to 10# before glue and screws. But I did some additional sanding once everything was in.

I'm soaking up all your testing ! Thanks for sharing !
I love your test seat !

Jim

 

[latremorej]

That's awesome SG! I'm excited for you! Can't wait to see the final numbers

Jason

 

[latremorej]

This thread has me thinking about weight and portages a lot lately. The following chart represents an additional 5lbs (6 pack) in relation to distance portages.

100m. - what beer, I should've packed more

500m. - hardly noticeable, I'm glad I have 6 beers for tonight

1 mile- dang! I could really feel the extra 5lbs, but the extra effort equals extra tasty and more rewarding at the end of the day

3+ miles- WTF was I thinking! This is heavy. My shoulders are fricking killing me! I wonder if I leave them by this stump if the next guy would enjoy them?

So, even if you don't come in at 30lbs, it will still be an easier carry while bushwhacking into your favorite places. Well done SG.

 

[stripperguy]

Curious to see what you come up with on your foam and glass test panels. Do you think the foam will be quite a bit lighter than a cedar core of 3/16". I think the foam by itself would be somewhat lighter but if it soaks up resin it's hard for me to guess what it would end up weighing.

The Divinycell is a closed cel PVC, I dont think it soaks much resin at all.
Most cedar is 22 lbs/cu ft, the H80 stuff is 5 lbs/cu ft...somewhat lighter??

 

[stripperguy]

Yup That's a carbon Copy !

It doesn't surprise me, that they handle the same. The big difference comes at the portage.

I weighed the trim and seats for Vader at very close to 10# before glue and screws. But I did some additional sanding once everything was in.

I'm soaking up all your testing ! Thanks for sharing !
I love your test seat !

Jim

Jim,
I was initially shocked when I saw how much the foam/carbon gunnels added in weight. If I had a thinner carbon, gunnels could have been 1/2 the weight!!
Gonna start some more test panels tonight, the d ouble sided 2 layer 6 oz has mostly cured now, it's like a brick. Way stiffer than necessary.

 

[stripperguy]

That's awesome SG! I'm excited for you! Can't wait to see the final numbers

Jason

I'll call it now, 28 lbs complete. Pretty sure I can do better.
Oh, and I don't drink beer! But I do carry long distances!!

 

[wingnut]

Thanks for pointing out the weight differences between the foam and cedar. That's a huge difference. Would the foam be rigid enough to span the form stations on a typical build with additional stations installed to cut the span down to about 6".

 

[stripperguy]

Thanks for pointing out the weight differences between the foam and cedar. That's a huge difference. Would the foam be rigid enough to span the form stations on a typical build with additional stations installed to cut the span down to about 6".

Haha...I know what you're thinking!! I am planning something similar. The 1/8" H80 foam is surprisingly rigid, it will take a 2D curve readily. But any compound curves would need heat forming, which is commonly done. Whether it would bridge between 6" forms without excessive distortions, I dunno. The foam could be cut to strips and run lengthwise, just like any stripper. If so, a bead and cove could really help retain a fair hull.

I've watched youtube videos about boat builds in female patterns using battens (or temporary stringers) along the length of the boat. But those guys were building with thicker foam, and used some screws from the backside (outside of boat) to hold the foam until the inside could be glassed.
How to hold 1/8" foam in place is my question? Maybe some weak hot glue? Whether building inside female patterns, or building on the outside of male patterns, or even a plug, the issue of holding the foam will still be the major challenge.

If you happen to have a female mold that is vacuum capable, all problems would disappear...Or if you could heat mold the foam for a half hull at a time.
I do think this sort of lamination schedule holds great promise, just need to sort out the details.

But, back to this build for a few minutes. I noticed when I went out for the test paddle that the seat rails that I added to the renowned Gage seat were too short. The seat could rock back, tilting the front of the seat up. So I added some foam to extend those rails and prevent that tilting. And I also cut up the last of my 2" foam to make up the future seat pedestals.
Here's a look at seats rail extensions and seat pedestals. All the foam will be radiused and wrapped with some 6 oz glass. I'll probably cheat and paint the glassed sections black, to look like carbon fiber. No one will ever know. Oops!

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[wingnut]

Here's a video of a foam core boat build using male forms instead of female forms like the one Muskrat posted.
https://www.youtube.com/watch?v=Nlg8AbWRV_c&t=27s

 

[Sven]

does double sided tape stick to the foam? If so, maybe you could run a strip over each station for your temporary hold. This would be assuming you can flip the boat with stations in place. Maybe test some window shrink double sided tape for compatibility.

If you built a "foam stripper" would you glue the strips together with epoxy?

Or maybe it's compatible with some flavor of plumbing cement?

 

[stripperguy]

wingnut and Sven,
Thanks for the youtube link and the thoughtful insights.

That sailboat build is just how I built mine, but I used 1/2" cedar and Okoume plywood.
I would much prefer to build on male forms. I have almost 40 years of experience with that technique...
Double sided tape? Maybe, as long as it's not too strong. In a former life as a toolmaker, I would often machine and grind parts held in place using double faced tape only. Usually needed a solvent to get the parts free.

I would use a thickened epoxy to join strips, I would be afraid that a solvent weld could quickly get out of control.

I gotta say, I'm getting pretty excited abut a foam cored composite build. MDB has been bugging me for years to try something like that.
Timing will be the issue...we are planning to sell our home shortly and will likely be homeless for up to two years while we build the new house. I joke about "homeless", we will probably occupy one of our rental properties. We have a 3 bedroom cape that we can occupy for a while, but virtually no room for a boat shop!!