NZ options in strip-foam resources?

Discussion in 'Boat Design' started by cutawaycafe, May 15, 2013.

  1. cutawaycafe
    Joined: May 2013
    Posts: 22
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Wellington New Zealand

    cutawaycafe CutawayCafe

    Hi,

    Thinking locally to NZ for now, what types of foam are available here? Specifically for strip-foam build-up of cores for two 44' cat hulls, to be covered in CF/epoxy inside and out. No radical radiuses, but a decent compound curve along the hull length. Is it a good idea to buy as strips? Or, to cove-cut your own strips as required, using fuller sheets where possible? It looks like 15mm to 20mm is about the right thickness.

    If advice can be given from overseas on what foam to seek in NZ, that is also appreciated. Regards, Dan (Wellington)
     
  2. garydierking
    Joined: Sep 2004
    Posts: 136
    Likes: 17, Points: 18, Legacy Rep: 174
    Location: New Zealand

    garydierking Senior Member

    Contact Gurit in Auckland. They used to be High Modulus and have all the good cores.
    info-nz@gurit.com
     
  3. groper
    Joined: Jun 2011
    Posts: 2,467
    Likes: 121, Points: 73, Legacy Rep: 693
    Location: australia

    groper Senior Member

    As above ^^^

    You dont buy the foam in strips, you cut it yourself, a circular saw or table saw goes thru it like a hot knife thru butter, so easy.

    Have you done your preliminary cost estimates for these materials? Foam cores in australia, will cost you around $150-$180aud ( 15mm and 20mm respectfully ) per 2400x1200mm sheet, assuming you get good supply prices - not retail.

    Carbon fibre is best imported from the USA, suppliers here are rip off merchants on this stuff. typical price i was quoted here is around $50 per m^2 for a 600gsm dbias stitched. Compare this to e-glass and your down to around $5 per m^2... "high modulus" use heaps of carbon so maybe you could get better prices, i dunno...

    Not trying to rain on your parade, but i hope you have deep pockets if you plan to build a large carbon multihull...
     
  4. cutawaycafe
    Joined: May 2013
    Posts: 22
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Wellington New Zealand

    cutawaycafe CutawayCafe

    Thanks Groper,

    Surface area of each hull is 90m2. CF cloth (200g twill) can be had for NZ$30/m2 for small quantities. I'm trying to find out how an order of 400m2 (two hulls, one layer inside and one layer outside) will drive price down. USA sounds like a option. Right now I believe I'm looking at around NZ$12k at $30/m2 (allowing 10% wastage). I have still to find out what weight/type of cloth to use, how many layers etc.

    The foam core prices here are comparable to your's. The cove cut was what made me think it came pre-strip-cut. I would prefer to cut my own sheets.

    My budget for finished but unpainted CF'd cored hulls and beams (CF, core and epoxy, plus shed rental and some hired hands on the critical days) is NZ$50k.

    Regards,

    Dan
     

  5. groper
    Joined: Jun 2011
    Posts: 2,467
    Likes: 121, Points: 73, Legacy Rep: 693
    Location: australia

    groper Senior Member

    Dan,

    200gr twill has no place on a boat... any boat, ever...

    If you want to build a racing boat, the majority of the hulls will use 600gr double bias stitched reinforcement, both sides of the sandwich. Woven cloths are not used in structural applications because the woven physical nature means that the fibres are not straight. If you put something thats not straight, in tension or compression, it will fail much sooner because it will buckle - think about it.

    From the questions your asking on this forum, i think you have alot more homework to do or risk blowing a huge chunk of change. Im really trying not to be patronizing, but designing and building a large carbon multihull is well beyond the scope of non-professional engineering.

    If you want to build more of a fast cruising boat, then 600gsm of carbon on your hulls whilst being strong enough, wont give you much in the way of impact protection. Even a small knock will punch a hole in your hull. Carbon whilst very strong, is also very brittle with very little stretch. So it wouldnt be a very safe option to go cruising with. At the very least, you would add extra e-glass or aramid (expensive option) to the entire below waterline area...

    How will you design the carbon beams?

    How will you build all this, wet layup, vac bagged or infusion?

    Have you had any experience with composites before?
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.