favorite epoxy with divinycell H80

Discussion in 'Fiberglass and Composite Boat Building' started by rturbett, Aug 31, 2010.

  1. rturbett
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    rturbett Senior Member

    their website does not seem to be working. Do you know if they offer it in 6mm thickness?
     
  2. sabahcat
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    sabahcat Senior Member

    Found some info here

    The bolded bit does not sound light
    I would have thought for a cat being built from divy and epoxy (so seem to be looking for light construction), kevlar would have been more the call.

    From experience on foam, using glass defeats the purpose somewhat. (more glass more resin needed to get same stiffness of say cedar and lighter glass less resin)

    What size hull rturbett ?
     
  3. tinhorn
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    tinhorn Senior Member

    Take another look at the picture. It's hollow on the inside--it's only the connecting glass threads that are impregnated (unless you use too much resin). A cured layup is unbelievably light and rigid.

    I can't get anywhere on their site, either. Here's some info from 2001:
    http://composite.about.com/library/PR/2001/blparabeam1.htm
     
  4. sabahcat
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    sabahcat Senior Member

    Yeah, I did see that it appeared to be a hollow core.

    I would be interested to see what the sheer and compression strength is compared to various foams and nida core or polycore which have a similar sort of look.

    http://www.nida-core.com/english/index.htm
    http://www.polycore.com.au/index.php

    These have been known to occasionally fill some of the hollow cells with resin, especially if vac bagged.
     
  5. rturbett
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    rturbett Senior Member

    These are Shark Catamaran hulls, 20 ft long, built on a male mold.
    The capillary action makes sens, but how consistent is the rebound? not as critical on a female mold, but if its not perfect on a male mold, lots of fairing work to be done.
    Just read your note again- my mold is for 1/4" (6mm) skins- that thickness seems to be missing...
    Would like to know if this product would support the focused weight of a boat when on the trailer arms.
    Only other concern would be repairing- how much water would the skin hold if there was a puncture. probably drill a hole to drain it.
    Rob
     
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  6. waikikin
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    waikikin Senior Member

    Rob, those Shark catamarans look like great fun, I like the way they fold for transport & storage & they have a nice retro cool vibe about them. All the best in your endeavours from Jeff.
     
  7. rturbett
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    rturbett Senior Member

    They are a blast!
    We have rebuilt a number of them, and they come out a bit heavy compared to a fresh build.
    John Rogers builds a cedar hulled shark- definitely the gold standard.
    I have made one with balsa core, but others are a bit skeptical of the durability of balsa. I love it.
    I disagree with them, but I spend a bit more time taking care of my boat then they do. Anything bringing a boat closer to maintenance free is a good thing these days.


    We spent a lot of time trailering our Shark this summer, Went to NJ to do the 40 mile Statue of Liberty Race, Down to the Outer Banks of north Carolina, And up to Michigan for the Nationals. With it folded in half, you can forget its there because it doesn't even show in the side view mirrors. Much easier to drive with than our Hobie 16.

    I cant say enough good things about how much I love the way it sails.
    The Nationals we had were the 48th Annual. Thats just a bit longer than I have been alive. they must have lasted this long for a reason...
    Rob
     
  8. tinhorn
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    tinhorn Senior Member

    That would be an interesting study. I don't know, having never played with honeycombs. Bagging Parabeam is out of the question.

    My experience with it was that rebound was very consistent. Again, a resin-rich area would be more troublesome--then it's time to grab the soppin' roller.

    Speculating here: Compared to honeycomb core, probably equal or better. The connecting fibers are 'glass, not paper or polypropylene. Compared to foam, I think performance would be superior since an impact wouldn't tend to tear the Parabeam apart in the same way foam delaminates from 'glass at impact.

    I think you'd be more likely to see printthrough with honeycomb.

    Probably LOTS. When I was using this stuff in the 90s, one of their pitches was that it would be excellent for double-wall tanks.

    I'm certainly not an expert on Parabeam but I was fortunate enough to have played with a few rolls of it, and I think it's pretty impressive.
     
  9. rturbett
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    rturbett Senior Member

    one of the Sharks has a honeycomb deck-
    I would never use it for our applications after seeing how it has performed. It has held up, but not as stiff as people were hoping.

    I would like to play with the Parabeam. Know if there are any us distributors?
     
  10. tinhorn
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    tinhorn Senior Member

    I found an email address not long ago, but got no response. Maybe if you make them think you order supplies by the railcar load, they'll talk to you. I hope you'll share your experiments with us.
     
  11. Herman
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    Herman Senior Member

    Forget Parabeam for hulls. Not even dry sailed hulls. (been there, done that). Parabeam has its merits, but not in general boat construction.

    Double walled tanks are OK, you can trace leaks, and it acts as a security measure, and there are more applications, but shear strength and impact resistance leave a lot to be desired.

    About Nidacore: basicly same problem. Low shear modulus, but quite impact resistant. However, quite heavy for the desired stiffness. The only thing I liked after all was the ability to bend it into 3D shapes, which made me do a hull in 6 panels instead of 20 or so with PVC foam. The cells will attract water after some time. Yesterday I talked to a guy owning one of my old boats, which was 85 kgs at the time, but 99 kgs now.

    If I were building a hull now, I would either use balsa, PVC foam or SAN foam.
     
  12. rturbett
    Joined: Aug 2005
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    rturbett Senior Member

    Thanks for the info- looks like divinycell will be the winner for this next set.
    One thing I did like about it was how easily it sanded. Pretty simple to work with-not a whole lot different than balsa sheet
    Rob
     
  13. tunnels

    tunnels Previous Member

    Tell every one why hand laid glass is surpoedly stronger than a gun laid hull , 10 -20 % is a bit of over the tip !! If you love dino tin boats why are you on a composite site for ?? :confused:
     
  14. apex1

    apex1 Guest

    Tunnels you should learn about GRP composites before you open your mouth!

    And read before you contradict!

    Adding 10 to 20% resin weight in a calculation of layups is the proven method to estimate the final weight, given the laminate is not vac. bagged or infused (nobody uses chopper guns and nobody did mention that), and given that the handlayup is not executed by a trained crew which can achieve a 50/50 laminate.

    So, one calculates the resin weight being equal to glass weight in a professional handlayup, adding 10 to 20% resin weight in a homebuild. (depending on skills)

    All clear amateur?:D
     

  15. waikikin
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    waikikin Senior Member

    We should know more about the laminate schedule for the Shark catamaran to make an informative comment on this, I could "guess" at one or two layers of light cloth either side of the core. Regards from Jeff.
     
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