Honeycomb fiberglass hull...

Discussion in 'Projects & Proposals' started by Externet, Jun 23, 2009.

  1. Externet
    Joined: May 2009
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    Externet Junior Member

    Good day to all.
    I know nothing about, that is why am here, to listen and learn.

    Not about engineered commercial composite panels, but a third-world approach to make a hull of this type. Please let me know your comments for an unusual approach.
    There is no calculations on thickness nor on strength. Just looking for qualitative opinions on this description:

    An existing hull, to be used as a mold; upside down covered with plastic film. Let's say 60 feet long, 15 feet wide.
    A ~half inch layer of fiberglass cloth, o mat, or chop or a combination of them properly applied with resin on top of the film.
    As this final resin is wetting the outer layer, placing bamboo slices one next to the other as to form a honeycomb layer, lightly pressed-in.
    They are 4-to-5 inch diameter bamboo slices, say 1 inch tall, half inch wall, all in contact with their 'neighbor' slices.
    After set, a second ~half inch layer of properly laid fiberglass and resin.
    With the proper reinforcing attention and considerations to any edges or areas that deserve it.
    After removed from the 'mold' and righted up, to add internal strengthening members.
    I do not know how to obtain figures for bamboo strength calculations when used that way. By 'smell', I would say brutally strong. The sawed edges of the slices are very resin wicking-adherent.

    Thanks. :rolleyes:
    Miguel
     
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  2. Ad Hoc
    Joined: Oct 2008
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    Ad Hoc Naval Architect

    have to be very careful with bamboo...it seems to contain loads of weird bacteria once cut (not present when growing), which slowly eats away the bamboo. has been a problem with bamboo furniture and all sorts for many years..despite lots of research to stop it.
     
  3. alan white
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    alan white Senior Member

    Try PVC pipe instead. You will have to pre-fill pipe with foam before cutting, then it might support the glass/resin applied over it. I wouldn't want to be the poor fool running the cross-cut saw.
     
  4. Externet
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    Externet Junior Member

    PVC... would the resin aggresively stick to it ? Seen ~1/16" thin wall fiberglass pipe, could be used for the slices too... or treating the bamboo as it is practically a $0 material.

    Would such contraption hull work ?

    Miguel
     
  5. alan white
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    alan white Senior Member

    I'd experiment. Make up a few test panels. PVC seems to marry to polyester resin in my experience, but someone else here may actually know how well they bond.
    As far as saving money on the hull, bamboo may be cheap, but I'd do a solid layup for the same money and stiffen with stringers. I personally don't like overly stiff structures because they are like eggshells. The do not yield a lot.
    Stringers aren't stiff (like a modern fiberglass-framed camping tent. Bash one with a baseball bat. Does it break?)
    Racing is another matter. Racing boats count on stiffness to carry huge loads without a lot of weight. But they don't suffer damage well, like punctures from underwater objects. In other words, I am wondering if you are attempting to get a very stiff hull, and if so, if it is intended for a specific purpose.
     
  6. Jimbo1490
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    Jimbo1490 Senior Member

    RE: PVC and poly resin: They don't bond well, not permanently anyway. But your idea is interesting, and there is a plethora of tube-shaped goods out there to choose from, many of which will be compatible with all the materials at hand.

    But you need to consider is how the combination of drape and vacuum (you are pretty much committed to vacuum bagging to join the second skin to the core) is going to affect the practicality of this concept. Think of the cell size used with typical honeycomb. It's usually no bigger than 10 mm, maybe 13 mm max. Wet cloth will not sink very far into the open span of such a small cell, though it sinks in some. If you use a really big cell size as you are proposing, the wet cloth is going to sink WAY deep into the cells once put under vacuum, which will not be acceptable for a number of reasons. Going to a more conventional cell size will mean many hours fiddling with tiny tube cut-offs, gluing them in place one by one. Sounds like a job for the new guy :D

    Anyway, it's a dilemma you need to face.

    Jimbo
     
  7. duktig102
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    duktig102 New Member

    hmm

    resin does not stick to the bamboo. Get a better effect by using epoxy resin. Personally, I do not support combining resin with wood. These two materials work differently, there is a separation. Try an alternative to bamboo, to do just fine pleated laminat.Po Strengthen shape. In such a laminate is difficult to make a hole in the outlet and is very strong. And when it comes to repair it recommend.
    http://www.laminat-repair.co.uk/

    Mvh.Sylvester
     
  8. apex1

    apex1 Guest

    Do you refer to Polyester when saying "resin" ?

    Both are resins, Epoxy too!
    And the combination of wood and Epoxy resin is a perfect boatbuilding material.
     
  9. sabahcat
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    sabahcat Senior Member

  10. duktig102
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    duktig102 New Member

    hej

    said resin I mean resins, polyester or the cheapest. I agree that the epoxy resins and wood are an excellent example of hockey sticks (low temperatures, powerful forces strokes). Most polyester resins are used for economic reasons and no fire resistance. In addition, epoxy resins cure to a long (at 18-22 ° C 99% strength for 30 days at 80C is a time of around 4-5 hours but note too quickly achieve a sea temperature of 80C to cause boiling of the resin and foaming and even a large number of explosions . As for the merger of the two resins with wood proposes to perform the test: stick a piece of bamboo mat stick to the outer part and then hit him, deflect, destroy. I know the result. in the next week I will try to post on my site http://www.laminat-repair.co.uk/ a few photos, and ways of combining polyester resins with wood.
     
  11. apex1

    apex1 Guest

    You should give up drinking!

    And remove the "quote" above, I do´nt post in such languages.:(
     
  12. CDK
    Joined: Aug 2007
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    CDK retired engineer

    I'm mesmerized by the word "honeycomb".
    Bees make those without any core material or measuring devices yet can maintain uniformity and even build them over curved objects.

    Genetic manipulation to make bees with epoxy glands instead of bee wax would be a major breakthrough in boat building. The little insects are hard workers with little needs.

    Alternatively, a study might reveal the bee's secret so we can build machines that produce honeycomb in the desired hull shape.
     
  13. gonzo
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    gonzo Senior Member

    I'll sign up to be a drone :)
    I don't see any advantage over a foam core. The fiberglass would be all lumpy even if it adheres. Also, the voids have to be filled with something other than resin or is will be very heavy and expensive.
     
  14. Herman
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    Herman Senior Member

    One small addition, ISO-NPG polyester adheres to PVC.
     

  15. Jimbo1490
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    Jimbo1490 Senior Member


    I thought of this decades ago, but with wasps or hornets. They make honeycomb nests too, but from a much more useful material: paper (cellulose fiber). Without any genetic manipulations they can be persuaded to make their paper honeycomb in a way that's useful, such as covering a complex shape. Then the paper can be impregnated with a thin resin to add strength, then covered in skins.

    I'm not sure any of this has a shred of practicality, but it was an interesting thought experiment, anyway:cool:

    Jimbo
     
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