Anyone ever use Formply ?

Discussion in 'Materials' started by boat fan, Sep 28, 2011.

  1. boat fan
    Joined: Sep 2008
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    boat fan Senior Member

    Hello

    Has anyone here ever used Formply ( concrete formwork plywood ) for Hulls?

    Would it be suitable to build a river scow (maybe 30-40 ft) , ( no real curves , just raked transoms ).

    Would it need surface treatment , ( is it epoxy coated? ) .
     
  2. Landlubber
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    Landlubber Senior Member

    boat fan, horses for courses mate, you could use it if you have a limited life expectancy and it was sheathed with epoxy for waterproofness, BUT it must be thoroughly treated, no missing areas and expecting it to hold up.

    As it is 16mm(?), it will not bend really at all, so flat sheet design will be the limitations of the product, it certainly stands the use of time as a concrete former doesn't it.

    I would only use it on a low cost, limited life time application. Make pontoons for a houseboat that is expected to last 10 years and scrap it after would sound about the limit.
     
  3. boat fan
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    boat fan Senior Member

    Yeah ...I think yourè right ......its actually not that cheap , as you probably know.

    I thought it would last longer than that.
    It`s 17 mm I think ....

    Thanks .
     
  4. PAR
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    PAR Yacht Designer/Builder

    Form ply is HDO and it's not a good idea to use in a boat. This is because the resin paper applied, is designed to shed whatever is stuck to it. Not much will stick to this stuff, such as paint, glues, adhesives, epoxy, sheathing, etc. MDO would be a better choice, though sometimes this also has a "form" coating, so make sure it doesn't or you'll never be able to paint it, glue it, us a sealant on it, etc.
     
  5. rberrey
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    rberrey Senior Member

    I have glassed over form ply years back, also read about a keel made of form ply that has held up for years. Form ply is a big word, included as form ply is BB pine, BB fir, MDO, HDO, Baltic birch in various forms. The skin if any would have to be removed and any precoated form releace would have to be removed , as PAR said it is designed to keep concrete from sticking to it. That said Finform or Russian baltic birch form ply is hard to beat when it comes to strength and durability, I have some Russian ply strips that have been in the yard for 10 or more years with no delamanation. I will use it under my mast in my build. If it has been poured on then the form releace is less of an issue, if you use any there will be prep work, but if its free it may be worth it. Check for voids they run from none to some depending on the brand and run. Finform or Russian birch will be less of a gamble, bullet proof but heavy. Rick
     
  6. boat fan
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    boat fan Senior Member

    I had some sheets of it years ago , I built some outside play equipment with it for my children.There was a slippery dip and a climbing frame and "cubby "house.It was outside in all weather for years.It`s been handed on to another group of happy little souls dishing out all manner of punishment...


    My children are young adults now , so it certainly lasted.Its still in good shape today.I think its on its fourth or fifth color now.Paint was applied after i sanded with 40 grit ,that may sound like that is far too aggressive to use ,but it actually just dulled" the coating"...I painted it with "bond - crete "which is a cement bonding agent....then paint.

    I don`t know if the stuff made today is actually the same.It appears so...

    Anyway ...thanks for all the advice I think I may pass on the idea.
     
  7. rberrey
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    rberrey Senior Member

    A boat built of birch form ply will last for years , there will just be a few hurdles to over come. It will be hard to bend and you must sand the paper off, and any form releace. BB fir that has not been pre coated with form releace will also last and not have the problems of a skin that you will have with MDO, HDO , Birch form plys. If you can get the ply cheep then there is no reason not to use it. As someone who has used truck loads of it I would be very comfortable with most of it as an epoxy coated glassed core. Rick
     
  8. boat fan
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    boat fan Senior Member

    Thanks rberrey.

    This was only going to be a scow...no real curves to speak of.
    I thought I could kerf cut the stuff if needed , but quite honestly ,
    I could not ever be certain this stuff here is actually birch plywood , or the stuff I used years ago.

    I could be lucky , and it may prove durable , but I think for something like in this size its a little risky.


    I did not realize there were so many different kinds of Formply , but in hindsight , it should not be surprising.
     
  9. masalai
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    masalai masalai

    I used form-ply to slide my boat out of the shed, with a little liquid laundry detergent drizzled about to make it slippery...
     
  10. PAR
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    PAR Yacht Designer/Builder

    Boat fan, kerfing the plywood will destroy what plywood has going for it.
     
  11. Squidly-Diddly
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    Squidly-Diddly Senior Member

    use the formply for inner form of ferro-cement barge, then for

    super-structure with walkable roof.

    Yeah, several diff things called "formply". Some has hard smooth surface on one or both sides, some is just oil impreged plywood.

    While we are talking concrete forms, allow me to turn you on to this stuff.....

    http://www.amico-stayform.com/

    The pics don't really do it justice or show it really excellent uses. It is best for quick and dirty sealing of the bottoms of normal ply or plank forms. You just bend about 8" of it so the concrete pins it to the ground and overlap it about 4" on the verticle braces and its steel mesh interlocks to both the wood and other StayForm as soon as concrete hits and it takes care of its self from there.

    To add rebar just after a pour you just spear the bar through the mesh and wiggle it into place.

    For bulkheads no need to strip for next pour.

    Their pics are all of this stuff all nice pretty and straight, but its beauty is how it can bend and bulge all over and still hang on. I've never lost a pour and I've been very bold with this stuff.

    The panels can be ripped length-wise in a jiffy by yanking/zipping then over a 16d deplex nailhead(nail is driven into secure wood). Takes a little technique and 'Oomf' but it rips the sheets in about a second without tools. Key is don't let the mesh bendover and 'clump'. You are tearing the mesh one strand at a time, like ripping a phone book in half.

    The stuff weights about 1/8th as equal amount of formply.

    Tie-wires can be easily run through mesh and tie "vee" channels together.

    You can roll it up lengthwise into a pole and shove that through 5x14" vent to make forms under a house. Try that with plywood.

    Best for foundations on irregular or hilly ground, or anytime you aren't going to be saving lots of nice full sheets of form or plank material.

    Can be cut with carbide sawblade, but SPRAYS jagged steel shards. Most people wear goggles AND turn their head and cut 'blind' and still end up with little cuts.

    Expect fair amount of blood on the mesh from handling sharp metal, bring bandages.


    I wonder how this stuff would do as frame for ferro cement shot cret boat. It has a lot more structure to it than chicken-wire.
     
  12. SamSam
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    SamSam Senior Member

    The formply we used to get was real good plywood with no voids and lots of plys. The problem was, new, it came oil coated and any used formply of any sort is bound to be oil coated.
     

  13. rberrey
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    rberrey Senior Member

    Most of the new form releace agents are water base, form oil is just a heavy diesel fuel. Used from ply that has not been recoated with the form releace has very little water base form releace agent left on it. And depending on how much oil was applied, if not heavy, that ply will be fairly free of oil due to the heat of the cured concrete and absorbson. Rick
     
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