solid glass hull/floor

Discussion in 'Fiberglass and Composite Boat Building' started by Tungsten, Oct 29, 2013.

  1. Tungsten
    Joined: Nov 2011
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    Tungsten Senior Member

    I've been searching the site for single skin epoxy and not coming up with much.Any advise on key words I should be searching?I'm sure the info I seek is here somewhere.
     
  2. Mr Efficiency
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    Mr Efficiency Senior Member

    What exactly are you seeking ?
     
  3. Tungsten
    Joined: Nov 2011
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    Tungsten Senior Member

    I'm looking for ideas to make a hull/floor in a small drift boat.The ideal floor would flex when running over shallow areas but be stiff enough to not oil can when standing on.I've built one already with a foam cored floor,I'm finding it too stiff for what I need.I've thought of a thinner core but I think this will be too stiff also considering it needs a lot of glass to protect the core.This lead me to thinking of solid glass with epoxy.The floor on these types of boats are flat and rise at each end to create rocker, my thoughts were to make a simple mould from sheet stock to do the lay up.Then stich and glue together.
     
  4. groper
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    groper Senior Member

    Stiffness is proportional to thickness cubed... so make it thicker, and it gets stiffer very quickly, the foam core sandwich applies the same principal.

    The reason you wont find much info with solid glass and epoxy is because most use cheap old polyester to do solid layups - reason being you dont need the higher mechanical properties of the matrix like you may do when doing sandwich type panels. - This doesnt mean you cant do it, its just that its more expensive. That said, if you prefer using epoxy - as i do - then the same laminate thicknesses and types can be substituted either way for your purpose...

    As a wild guess, you might need something like a 3mm solid glass thickness for your floor in a small drift boat... hard to say without suck it and see for your desired stiffness... you can either do it from solid glass and resin at approx 30oz fibre per mm thickness or use a fibre skin with a coremat type bulker in the center to build thickness more quickly and save a bit of weight... so many choices with composites...
     
  5. Mr Efficiency
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    Mr Efficiency Senior Member

    I have seen powerboats laid up with single skin epoxy glass, the excuse for it was probably to eliminate the danger of osmosis as the boats were moored all the time, also it was for a govt department, so the taxpayers were paying !
     
  6. Tungsten
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    Tungsten Senior Member

    Thanks groper,just what I was looking for.
    Am I correct when saying even a thin core (6mm) won't give me the flex I'm after?
     
  7. ondarvr
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    ondarvr Senior Member

    Drift boat hulls that flex use no core, add a core and the flex will be reduced, you are the only one that knows exactly how much flex you want, so 6mm may be just right..or not.

    It also depends on your laminate schedule (type of glass and orientation).
     
  8. groper
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    groper Senior Member

    Ondarvr is correct, the fibre orientation and fabric type also plays a part in how it will flex.

    If you use a 6mm core, you can expect it to be about 4 times stiffer than a 3mm laminate of similar fibre type. remember stiffness is proportional to thickness^3.

    Iirc, you damaged the floor of your boat on some rocks? So you have a toughness problem with foam core panels in this type of usage, foam core panels are poor in this respect. So is this really about flex or toughness? standing on a very flexible floor won't be comfortable... My personal opinion is you want a solid glass floor for toughness that's also stiff to stand on...
     
  9. Tungsten
    Joined: Nov 2011
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    Tungsten Senior Member

    Great stuff,
    The damage I have is minor small dent/grove left from sliding over a round rock,you can just feel it.Simple fix ,more glass.The floor may have flexed more had my outer skin bin thicker.

    The 1/2"(12mm) foam floor flexs a little now when 2 guys are standing but not much,you get a little reverb when you stomp on it from the seat.So I think I'm close to what I need.

    From my searches I'm reading to make a solid floor, Ve resin would be a good choice?Better flex?This allows me to use matt to build thickness.Uni between matt.

    If I use epoxy and using gropers guess at about 3mm this is about 90 oz of cloth?I'm vacuum bagging by the way.12 oz glass is what I have,0 90 and 45 45 .Combinations are endless.

    I'm able to get 3mm foam,I think this maybe the solution,a thick outer skin and it should flex enough over shallow rocks.

    Thanks for your help.

    Go Red Sox
     

  10. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Epoxy would have better elongation properties for this application. Ultimately you'll probably need to make some test panels, to see how much flex you need, want and how to arrange the laminate.
     
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