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  • Carbon Copy

    Some of you here may remember the thread I ran when I built my "Kite". That was a 14' 6" J Winters designed solo open canoe, for combined whitewater and flatwater use. It was cedar strip built, with glass inside and out.
    While I was (and still am) very satisfied with the performance of the hull, at 39 lbs, it's just too heavy for me.



    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.

  • #2
    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.



    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!!

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    • #3
      Time to get real!
      Here's most of the supplies required, the PVA, the carbon fiber cloth, fiberglass cloth.



      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.



      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?

      Last edited by stripperguy; 01-14-2017, 11:09 PM.

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      • #4
        Originally posted by stripperguy View Post
        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?
        Nice touch (on suspense), that was the first question I had when opening this thread...

        Are you planning to air dry it or vacuum bag the composite mold? (assuming you plan to layup all four layers at once vs one at a time to minimize / avoid potential air bubbles / delamination problems in the future)

        You certainly have (at least) one interested follower for this thread, having never attempted anything of this scale before - very interested in your technique and results.

        Thanks for taking the time to share!
        Feverishly avoiding "a steady stream of humanity, with a view that offers little more than butts, boots, elbows and backsides". (description quote from Joe Hackett)

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        • #5
          Originally posted by timberghost View Post
          Nice touch (on suspense), that was the first question I had when opening this thread...

          Are you planning to air dry it or vacuum bag the composite mold? (assuming you plan to layup all four layers at once vs one at a time to minimize / avoid potential air bubbles / delamination problems in the future)

          You certainly have (at least) one interested follower for this thread, having never attempted anything of this scale before - very interested in your technique and results.

          Thanks for taking the time to share!
          My initial thought was to wet out all 4 layers at once, but after doing the little test patch, I think I will wet out the carbon first, then do the glass.

          I must confess, I am controlling history here, much more has been done than I have exposed so far. So return to yours seats and buckle up, there's a bumpy ride ahead!!


          As far as air bubbles and future delamination, I'm not concerned in the least.
          After wetting out with a roller, I squeegee all of the cloth to remove excess resin and eliminate any entrained air. The epoxy I'm using is reputed to cross link between successive layers as long as the time between layers is not more than 3 days. In my experience with this particular resin (over 15 years now) I have never had a delamination issue. Even when repairing damaged sections after years of abuse and subsequent abuse, nothing has ever refused to stay bonded.

          Now a quick (or maybe not) word about the potential removal of the shell from the Kite, henceforth called the plug.
          This particular hull has a pronounced "crease" where the hull flare transitions to an abrupt tumblehome. This crease allows easier paddling, and also add considerable stiffness to the hull. So much so, that it barely needs any thwarts. While I love the performance and aesthetic aspects of this crease, I can see where it will cause quite a challenge in making the carbon copy. The gunnel width is roughly 8 inches less than the maximum beam...the carbon copy will need to be stretched considerably to free it from the plug.
          To help, or actually to enable, this stretch, I'll leave the stems open, only sealing them up after removing the copy from the plug.

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          • #6
            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!



            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.



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

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            • #7
              I'll be very interested to see how the process works. I think it's a little more technical complexity than I would dare to undertake, but it seems like a really good idea for someone brave enough to try it. I have a few questions whose answers probably should be obvious but I haven't been able to figure them out. Will both fiberglass layers be on the outside or will there be one in and one out like on a strip canoe, and how will you keep the shell from sagging once you get it off the mold and before it gets fully cured and hardens?
              Zach

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              • #8
                Zach,
                I've been expecting you!!
                Yes, both layers of the 6 oz fiberglass will be on the outside, mainly for 2 reasons.
                The glass is much more abrasion resistant than the carbon...think of the carbon as pencil lead, it is almost that easily abraded.
                Secondly, most of the loads the hull will see will come from the outside. This puts the outer skin in compression, and the inner skin into tension. Carbon fiber has excellent strength in tension. This 3K carbon fiber cloth is rated at a tensile yield strength of 640 Kpsi, compare that to mild steel at about 30 Kpsi. Some high strength steel alloys reach 200 Kpsi. Also, the carbon fiber has a modulus in excess of 30 million psi, roughly the same as any steel or steel alloy. The modulus is the relation of stress to strain, most folks interpret it as "stiffness".

                As far as preventing sagging, I plan to place the nubile shell on a handful of the original forms, once I remove it from the plug. How many forms will I need? Dunno yet, but I have a full complement if need be. That little test patch was pretty springy, but it did maintain its shape, even when flexed nearly into a U shape, it still sprung back flat!
                So I'm not too concerned about maintaining the below the waterline profiles, but I do have concerns about replicating the profiles in the crease and sheer line.

                Lastly, I don't know if I would consider myself "brave". Blissfully ignorant, I would say. I don't know enough to be frightened!
                But then, I have always been a "go big or go home!" kind of guy.

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                • #9
                  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.




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


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                  • #10
                    That tumblehome looks like tough sledding but I'm glad it worked out in the end. I've experienced the problem of the roller bringing the cloth up with it as it rolls away, but that was with fiberglass on wood so it was just due to my bad technique and it didn't happen too much. It must be scary when it happens frequently and you're doing the whole hull at once. Will you have to wet out the two layers of fiberglass separately or can you do them both at once? Is that the basement of the new house you were going to build? I'll be interested to see what happens next.
                    Zach

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                    • #11
                      Originally posted by Zach View Post
                      That tumblehome looks like tough sledding but I'm glad it worked out in the end. I've experienced the problem of the roller bringing the cloth up with it as it rolls away, but that was with fiberglass on wood so it was just due to my bad technique and it didn't happen too much. It must be scary when it happens frequently and you're doing the whole hull at once. Will you have to wet out the two layers of fiberglass separately or can you do them both at once? Is that the basement of the new house you were going to build? I'll be interested to see what happens next.
                      Zach
                      Zach,
                      No, that's the basement beneath the addition for my dearly departed FIL. We're still here, prepping our house for sale in between apartment rehabs and side projects. We need to sell this house before we build the new one.
                      There are drawbacks to showing little income on a tax return...

                      So you ask about the next 2 layers of fiberglass cloth.
                      Here goes.
                      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.



                      And here it is part way through the wet out.



                      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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                      • #12
                        Neat!
                        Any chance of some video?

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                        • #13
                          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.



                          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.

                          Click here for video

                          My buddy hickoryskier 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.

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                          • #14
                            Cool video!

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                            • #15
                              Thanks for the updates. The video was very suspenseful with all of the scary noises as the hulls separated, I'm glad it all came off in one piece and I hope that all that work didn't set back your surgery recovery. It's amazing how fast it took shape, I've been used to strip canoe builds where the process is so much slower.
                              Zach

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