Ferro Cement

Discussion in 'Materials' started by Mark O Hara, Jul 19, 2020.

  1. Mark O Hara
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    Mark O Hara Junior Member

    Any NA's here that can do design calcs in Ferro Cement?
     
  2. TANSL
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    TANSL Senior Member

    I suppose that anyone who is used to designing ship structures could calculate a ferro-cement one, but for this you should provide the mechanical characteristics of the material you are going to use. In addition to this, the appropriate structural solutions for ferrocement will have to be taken into account, but that should not represent a major problem. I think that, above all, the ball is on your roof.
     
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  3. Pericles
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    Pericles Senior Member

  4. Alik
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    Alik Senior Member

    With ferro cement, calcs are not the issue. The details are important, and construction process. Many ferro cement boats fall apart from vibration, other serve for decades.
     
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  5. Yobarnacle
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    Yobarnacle Senior Member holding true course

    I once ran a re-powered diesel tug built in the 1930s as steam,, with a riveted iron hull, but wooden deck and house. Engine and hull were good. The wood was badly deteriorated and needed replacement. The new owner replaced deck and curved front whelhouse with ferro-cement. Roughly finished, but it was a workboat, not a yacht. The straight sided after part of cabin was sheathed in new steel plate.He painted the deck and cabin with white road marking paint. Lasted well!
     
    Last edited: Jul 19, 2020
  6. Alik
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    Alik Senior Member

  7. Yobarnacle
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    Yobarnacle Senior Member holding true course

    There is a ferrocement hull in Green Cove Springs Marina, Fla.
    Never fitted out, only the hull built.
    I expect could be cheaply purchased.
    Looks like about forty feet LOA.
    On the hard. (stored on land)
     
  8. bajansailor
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    bajansailor Marine Surveyor

    Mark, what exactly do you want to build in ferro-cement?
    (I presume that you do intend to build something, re your question about NA's?)
     
  9. kapnD
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    kapnD Senior Member

    Many marinas and boatyards sport one or more like that, waiting to be crushed and dumped.
    Ferrocement seems to be attractive mainly to persons who are not Boatbuilders, maybe because they perceive it as an easy and cheap method. Hull builds that cannot proceed quickly suffer from cold joints and metal corrosion, and are doomed to never float.
    With modern materials, I’d say that ferro could be a very viable medium for hull building, but there’d be a great deal of epoxy, and no metal involved.
     
  10. Pericles
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    Pericles Senior Member

  11. Yobarnacle
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    Yobarnacle Senior Member holding true course

    10. RULES FOR THE CONSTRUCTION AND CLASSIFICATION OF FERROCEMENT VESSELS http://www.fao.org/3/v9468e0d.htm
    Maybe this will help

    "For reviewing the structural details of fishing vessels we would obtain required steel scantlings from our Rule for Steel Vessels Under 61 m in Length and convert these to ferrocement scantlings using the following relations:

    [​IMG]

    [​IMG]

    [​IMG]

    Where
    ffc = Allowable tensile stress in ferrocement

    SMfc = Section modulus of ferrocement

    SMms = Section modulus of ABS mild steel

    tfc = Thickness of ferrocement

    tms = Thickness of ABS mild steel

    M.R. = Modulus of Rupture of test sample (stress psi at which cracks of 1.100" in width appear during the flexural test)

    "The value of 15,690 pounds per inches squared in the above formula is the presumed allowable tensile stress for ABS quality mild steel. Depending on the location and orientation of the particular member it may go up to 20,160 pounds per inches squared.
     
    Last edited: Jul 19, 2020
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  12. Mark O Hara
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    Mark O Hara Junior Member

    My apologies, there has been numerous replies and I didn't get any notifications via e-mail. I am doing a feasibility study on building a ferro-cement version of the Pasig Casco about 21.3 m (70ft) x 3.65m (12ft) Traditionally they were built out of wood, but wood doesn't last long in fresh water here in the tropics. So I'm thinking either steel or ferro-cement. Steel is straight forward but with ferro I'd prefer someone with a lot more knowledge in it than me come up with the framework and the hull thickness. A_casco_(barge)_in_Manila_Bay_(1906).jpg
     
  13. Pericles
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    Pericles Senior Member

  14. Mark O Hara
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    Mark O Hara Junior Member

    I have to admit the Russians are pretty bloody good when it comes to detailing engineering. I have a friend from Sochi, living here, great engineer, bike and boat builder, I have another that designs ekranoplans and flying boats, I may build one of his some day! Thank God for Google Translate! :D
     

  15. Mark O Hara
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    Mark O Hara Junior Member

    Thanks, had I been closer to home I'd take a boat down the Thames and model it off the many lighters at Rainham Marsh, but I now live 11,000 nm away. The fact that they were built during WWII and are still around today says a lot!
     
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