a boat from foam-fiberglass laminate panels

Discussion in 'Boat Design' started by TacoFace, May 29, 2021.

  1. TacoFace
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    TacoFace Junior Member

    Don't know if these pictures reveal much. ...and someone might want to delete my duplicates... I broke a piece of the laminate and some of the separated foam, if that shows you anything about the material.
     
  2. Mr Efficiency
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    Mr Efficiency Senior Member

    Hard to say, but probably standard density foam and chopped strand lay-up. No great value as a boat build prospect, good for ice boxes.
     
  3. sharpii2
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    sharpii2 Senior Member

    I think it is possible to make a useful boat out of facets, which are flat panels that don't bend.

    I once had a thread on this subject which dealt with 1 ft models which had to conform to a sum rule (trading Beam for Draft) and other design limitations.

    These boats were to be handicapped based on the number of facets that make up the hull. The fewer facets a hull was made up of, the greater the handicap.

    I drew up two that only had 4 facets each. These would probably never win, even with the handicap.

    I have found that with as few as 8 facets, I could come up with a pretty convincing boat. 12 is probably a better number, but boats with that many facets might start losing due to the handicap.

    There are several ways to find the miter angles that don't require a lot of math. Simply dividing the inside angle between two facets by 2.0 will probably get you close enough.

    There will almost certainly be a performance penalty for using facets rather than curved surfaces, but if done right, it may be less than one might think.

    I will post a few examples when I get access to my PC.
     
  4. TacoFace
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    TacoFace Junior Member

    Facets. That's the ticket. Yes, please post.

    ....as far as the angle cutting, you're missing the difficult part. I can bisect an angle to get two cuts, but we're talking the angle of the glue-edge, if that makes sense.

    The exterior of the hull will be a 3d tesselated facet surface, the inside of the hull will also, but each piece itself will be a prism.

    Break down a socker ball into the hexagons and pentagons, that's just surface geometry, then give the ball 2-inch wall-thickness...

    ...ok, that is a bad example because those cuts would all be the same because it's a sphere, but a canoe shape is going to be

    Ok, I'm going back to sleep now. Will respond when awake. Ty
     
  5. Mr Efficiency
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    Mr Efficiency Senior Member

    Panels are too small to be much use for anything, admittedly they are an advance on polystyrene, but I would say making some iceboxes out of them seems the best use.
     
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  6. clmanges
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    clmanges Senior Member

    Maybe you could stack them up and make pontoons out of them.
     
  7. TacoFace
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    TacoFace Junior Member

    Point taken. I have other uses for them, was just playing around with the idea of small boats. My questions were really more about geometry than the materials. I'll definitely play around with those drafting programs.

    The fellow that mentioned his faceted designs for that contest I'd love to look at.

    You probably all saved me a bunch of time with the boat idea. I'll stick to non-marine construction.

    ...I am going to glue up a few pieces and sink them in the river for a week or so as an experiment though.

    Thanks again for yall's help.
     
  8. Squidly-Diddly
    Joined: Sep 2007
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    Squidly-Diddly Senior Member

    That looks like Clean Room building material....and I think I know why it became available.

    They ordered it but by the time it showed up some crazy spec or new certification was required and its not returnable so there you are. Many such cases.
     
  9. TacoFace
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    TacoFace Junior Member

    Nope, it is industrial door material. It wasnt a change order or anything like that. it's just the normal cutoffs from the normal manufacturing process.

    My questions really are about geometry and possibly hydrodynamics of an approximated curve made of rigid facets.
     
  10. fallguy
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    fallguy Senior Member

    These are probably pu door foam which is porous.

    I'd be curious to try to make them into strips.

    Rip a section off, 1/4" wide, the long way.
    Weigh it in grams.
    Soak it in a bathtub for 24 hours submerged.
    Towel dry it and weigh it again in grams.

    The weight delta will tell you whether it is porous and to what degree.

    Then take another rip and/or get the shear rating of the foam and glass it with the skins removed.

    It might be worthy of strip material with the csm a shear web. And then you could make most any boat from it. But you want to see if it delams super easily or if the shear rating of the foam is poor...
     
  11. TacoFace
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    TacoFace Junior Member

     
  12. TacoFace
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    TacoFace Junior Member

    Good idea. I'm going to soak a couple pieces and see what happens. I read the thread on here about the guy with the crappy double-skin boat with injected foam that absorbed water. I'm definitely not using it if the foam absorbs water.

    If it works for small day craft itd be fun, but I have plenty of other uses for it.
     
  13. Mr Efficiency
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    Mr Efficiency Senior Member

    A "faceted" boat would likely be more trouble to build than a non-faceted one, even if the end result was tolerably effective in use. That is a lot of awkward joining, and potential lacking in structural integrity, unless meticulously attended to. You don't see it, because largely it is not gaining you much, even if a bunch of free panels land in your lap.
     
  14. Mr Efficiency
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    Mr Efficiency Senior Member

    PU at that density is subject to *some* water absorption, but you don't leave the foam exposed to water unless you want to prove to the world it will absorb water. The idea is to keep it out of direct contact. PU foam has a lot of knockers because of the horrors of water absorption, which does happen and get worse with time, but there are thousands of people alive today because it was installed in the boat, and an awful lot who perished for want of it.
     

  15. Rumars
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    Rumars Senior Member

    Soaking the panels is useless, you don't gain any insight from it. You are interested if they can absorb water trough the installed fiberglass skins, not if the foam itself is porous. A better test would be to make a box and fill it with water, then weigh it every year.
    Best thing you can do is build boxes and sell them, then use the money to buy the boatbuilding materials of your choice.
     
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