Ferrocement questions

Discussion in 'Boatbuilding' started by baboonslayer, Oct 8, 2011.

  1. baboonslayer
    Joined: May 2010
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    Location: Colorado

    baboonslayer Junior Member

    I know the traditional ferrocement boat building method is to build a re-bar frame and put a chicken wire mesh over it, then coat it with concrete (I know it's not really that easy and simple, but that pretty much sums it up). The question I have is about the re-bar frame. Why do you have to use re-bar when you could just build a wooden frame? A wooden frame would be so much easier to construct, and not to mention lighter. Some other questions I had were about the hull. Do you (or should you) coat it with anything like marine paint, and also, what is the best mix ratio for the concrete?
     
  2. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    A wooden frame will swell with moisture and crack the cement
     
  3. baboonslayer
    Joined: May 2010
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    baboonslayer Junior Member

    I see. So no wood on a cement boat then. Thanks for the input. Another question I had was about the mix ratio of cement/sand/water. Isn't it 15% cement, 65% sand, 20% water for the best strength?
     
  4. viking north
    Joined: Dec 2010
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    viking north VINLAND

    The other factors are strength and adhesion. The mixture for boatbuilding has other additives and depending on which stage of the build you are into(hull layers) some builders vary those additives and add other ingredients. The final hull should be coated with a good barrier coat--many use epoxy paints. If you are serious about building such a hull you need to dig into the literature on such and track down an experienced ferro builder to work on the actual building of the hull with yourself and all the friends that owe you favours on the big lay up day. If you need 10 people ask 50 -- 40 will have excuses they can't make it--I call them TAKERS not GIVERS in life. Good idea to cull these out every 5 years--:)---Geo.
     
  5. jimcro55
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    jimcro55 Junior Member

    What size is this "wire mesh" that is typically used with the rebar to build a boat? I would think that the "openings" in the mesh had a lot to do with the strength and foundation of the boar frame? Obviously wood will not work due to cracking, but I would think the finer the wire cloth mesh used ( say maybe a 10 x 10 wire mesh - http://www.bwire.com/index.html ) the easier and stronger that the cement will hold. any trut to this thought process or am I completely off base with my thinking here.
     

  6. jimcro55
    Joined: May 2010
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    Location: Jersey

    jimcro55 Junior Member

    my apologies - just realized this was from October 2011 and not October 2012.
     
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