Pour foam

Discussion in 'Fiberglass and Composite Boat Building' started by groper, Sep 13, 2014.

  1. groper
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    groper Senior Member

    Yeah mate, the bulkhead has been glassed inside and out and all around... it's difficult to see because I've used up some left over bog by wiping it on the front of the bulkhead....

    I was looking for some better foam, higher density and finer cell structure than the usual buoyancy foam... These guys seem to have it erapol.com.au
     
  2. waikikin
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    waikikin Senior Member

    Great research Groper.... looks like Era does casting/molding rubber, I've got a couple of large plaques to reproduce soon, also they're inside a km from Nuplex plant.

    REgards from Jeff.
     
  3. rxcomposite
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    rxcomposite Senior Member

    Groper- I have used pourable foam to shape complex hull shape. It is not that good as it has very low density and has a tendency to shrink after shaping. I have to glass it over with a thin layer of FRP then lots of fairing compund.

    I have more success gluing (epoxy with micobaloons or corebond), off cuts of higher density core materials, then carving it to desired shape. If I wanted it to be removed afterwards, I apply mylar packing tape over the shape, otherwise, I just layup glass over it and let it form as part of the structure.
     
  4. rwatson
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    rwatson Senior Member

    Tried to tell him.

    Until you have done it both ways, it isnt that obvious.
     
  5. groper
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    groper Senior Member

    I case you can't read or comprehend in great detail, I'm not using buoyancy foam rwatson... I'm going to use a high density PU pour foam of ~70kg/m3 , about double the density of standard FG pour foam, and which has a fine cell structure and improved structural properties. It will shape like a surfboard blank, as many have done for decades...

    And for your information, whilst I have never used pour foam before, I have extensive experience in gluing foam together and trying to shape it afterwards. Quite frankly, it's a pain in the ***!

    And whilst I didn't care about the cost too much, the price of doing it all in divinycell would be pretty astronomical, it's $3300 per cubic meter in case you didn't realise. Compare that with pour foam @ $700 per cubic meter. Then there is a huge amount of time figuring out all the lofting and nesting of the 20mm thick section profiles, glueing them together, then you still have to shape it after anyway!

    So forgive my tone, but I think your advise is a bad way to go considering the other options available...
     
  6. rob denney
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    rob denney Senior Member

    We use ultra high density polystyrene. It is available in anything up to 2.4 x 2.4 x2.4 cubes. Pretty cheap, very easy to sand, does not absorb water (unlike many of the pourables) and good in impact. Needs 1 x 600 glass over it (with epoxy, not ester resins). Much easier than any of the other options, in my experience.

    A more expensive option is foaming epoxy. Sikomin have the best range afaik.

    rob
     
  7. rwatson
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    rwatson Senior Member

    Hi Rob

    Wheres the best place to get it in Hobart ?
     
  8. groper
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    groper Senior Member

    Cheers rob, but I already got some 71kg/m3 polyurethane pour foam en route. .. I'll let ya know how it goes, via a pour in place open top mold...
     
  9. rob denney
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    rob denney Senior Member

    No idea. Try Polyfoam

    Tasmania Office
    113 Cove Hill Road
    Bridgewater TAS 7030
    Telephone:
    (03) 6263 6900
    Facsimile:
    (03) 6263 6966
    Email:
    salestas@polyfoam.com

    Groper,
    Be a bit careful with the pour. Large volumes are best done in smaller shots or the consistency is all over the place, including big air bubbles. Mix it well (drill mixer) and quickly. I would do a small quantity, weigh it, then immerse it in water for a few days to be sure it won't soak any up. Some of the A+B foams are sponges and take a long time to dry out if they get wet.

    rob
     
  10. PAR
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    PAR Yacht Designer/Builder

    If I'm pouring foam and am concerned about moisture gain, I'll line the area with visqueen (plastic), spray mounted lightly into position, then do the pour. When the foam cures, I'll pop out the hunk, peel the plastic off then coat with epoxy, sealing it up, before dropping it make into position, possibly also gluing it in place.
     
  11. groper
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    groper Senior Member

    Ok so the product arrived and I finally got around to doing a small test batch of 40grams. This was the resultant block, mixed with a stick, in an icecream container lined with plastic.

    [​IMG]

    I cut the end of the block to expose the inner cell structure to see how well the surface will end up after hand shaping the bows of the boat in preparation for glassing over. I think it should come up great, a very fine structure with no large voids. The free rise density of this foam is 70kg per cu meter, or around 4.5 lb per foot for our imperial inclined friends across the pond :)

    I'll get around to forming up a rough mold for this soon, and hopefully get it poured on Sunday, but work is crazy at the moment I dunno if I'll get around to it for sure...
     
  12. PAR
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    PAR Yacht Designer/Builder

    Immerse it in a bucket of water for a few days, after carefully weighing it, then check the weight again, after it's pulled and dried with a towel.
     
  13. groper
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    groper Senior Member

    I'm not all that concerned with water absorption as the whole shebang will be encapsulated and glassed over with eglass epoxy. The data sheet says closed cell content > 92% if that's anything to go by? This stuff was sourced directly from a polymer manufacturer. They got so many different flavors of polyurethane found it difficult to select from the menu :)
     
  14. groper
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    groper Senior Member

    Heres the result of making the solid foam bows using the 70kg/m3 polyurthane pour foam... overall im pretty pleased with how it went. It was pretty easy to do, only took a few hours to do both bows including making the "molds" if you could even call it that :p A hour or so with planers, sanders and long board etc, and the surface finish is pretty neat, save a couple of pot holes :D

    Thanks to Jeff, for the idea :idea:

    [​IMG]

    [​IMG]
     

  15. Jim Caldwell
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    Jim Caldwell Senior Member

    Looks good and easy!
     
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