35ft Catamaran Hull: Filament Winding Possible?

Discussion in 'Materials' started by babu, Aug 28, 2012.

  1. rxcomposite
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    rxcomposite Senior Member

    Issue number 20 "Secondary Bonding Solutions" has the commercial version.
  2. Sail Nut
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    Sail Nut Junior Member

    Fiber Orientation is critical

    The problem with filament winding a large hull is that the main stresses are the stay and mast loads, so you want most of the fibers running longitudinally. A simple, 2-axis filament winder will easily wind around the hull, beamwise, but as the angle to the longitudinal axis gets shallow, there is difficulty keeping the fibers in place.

    It would seem that a more sophisticated 4 or 6-axis winder could do the job, provided it could rotate the hull in the pitch direction, so the fibers could be wound approximately over the keel, then bow, mast, stern etc. There are at least 2 difficulties with that: finding a machine big enough (I've never seen one, they probably exist, but aren't cheap) and making a mandrel strong enough to hold its shape while being rotated through crazy angles.

    There is also the need for interrupting the winding long enough to put in a core (eg. balsa), an oven large enough to put the whole shmear into, and to remove or abandon the mandrel. The outer surface will need some kind of coating to fill the grooves between filaments.

    I can't see any insurmountable barriers, but a major engineering effort and no signs of anyone with the M$ to find out if there's something not-so-obvious.
  3. tunnels

    tunnels Previous Member

    what a waste of time !!

    From a personal point I cant see any advantage what so ever in even attempting to winding a boat .
    Like has already been said orientation of fibres is critical specially for a light weight construction !!
    Its easier to just hand lay the uni glass where its required and in the direction that's needed most
    You can get rolls of uni glass up to a metre wide with a light 225 csm attached to one side or even lighter !!
    If you are thinking of using single strand or even anything less than 300 mm wide you gotta be nuts !!
    If your not nuts then you sure as hell need your bumps feeling :confused:!!
  4. Tanton
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    Tanton Senior Member

    We used the method of Filament winding to build carbon fiber free standing spars in the 70's. Epoxy resin and cured in an oil bath. The capability was up to 140' (a very tall tower). we never did. No demand.
  5. tunnels

    tunnels Previous Member

    Spiral winding there nothing wrong with the principle but its not for building boats !!
    The orientation of glass needed to build boats Is quite complicated , hull need to be constructed quite differently to decks and so the joint up of each is a place lots people get worried about !
    Unidirectional glass is something not many people really understand its enormous potential and what can be done with it .
    But remember all the glass cloths and materials out there in the market place are all using uniglass to make them !!,be it a single strand or hundreds of strands laid at many different angles ,its all uni glass to begin with !
    Glass manufactures are very clever people and are always coming up with new ideas and new materials for us to use , Its builders and composite engineering were the problems begin by trying to analyse the stresses and strains and loads of things we are making . There is so much we still really don't understand about a boat traveling over or through the water and add speed and everything you thought you knew goes out the window .
    There a great interest taking place now of making flexible boats !!
    Yip that's right hulls that flex and twist and panels that move !! Frames that bend and flex and everything stays together!!
    Its almost like reverse thinking and the ordinary person will never cope with it !!
    Vikings in ancient times made the fastest most sea worthy boats ever made and they principles of building are only recently being rediscovered .
    More than 22 years ago I made 2 boats for surf life saving .
    Breaking completely away and going completely against every ones know how of building surf boats they were flexible and twisted and softer to ride in and had a soft trampoline type glass floor inside .
    Immediately the benefits were apparent and the young surf life savers came back shaking there heads in disbelief at how much better they were to drive ,handle and added they could go faster and handle rougher conditions without having to back off the throttle .
    Sore backs , sprained ankles, broken legs all disappeared .
    New ideas and different ways of building are never accepted very easily and
    the older die hards of the surf life saving organisation poo poo-ed the boats as being to light weight ,flighty and would never last and would break up to easy .
    So we asked them to use the boats continuously for a month and spare then no mercy what so ever and even try to break them . The boats came back after a month and they gone over with a magnifying glass every where !! there was not one sign what so ever of stress marks and cracks or anything breaking !so back for another month ,again nothing . they got used and abused for the whole of the 4 months season and not one sign of damage !!
    Using only a sprinkling of csm between each of the 4 layers of the light weight uni glass was all that the hull had been made from including the transom with a 18mm thick h 80 core . The trampoline deck was one single layer of 600gram + gel goat of double bias glass . Out and off the mould the deck was flimsy and floppy until it was attached to the hull properly .

    Now there are movers towards flexible boats and soft decks there's are lots of experimenting and research taking place on these very subjects .
    Its all about flex and twist and panels that move !! all these things can be achieved by using uni glass .
    Panels that move absorb shock and don't break with the spin off of making a boat softer riding !!
    If you read back on some of my older posts I have mentioned these things frequently and not one person has picked up on it, not one !!

    Spiral winding and using uni glass is a very interesting subject !:D:p:p
  6. rxcomposite
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    rxcomposite Senior Member

    I think the original poster Babu has left. He won't be hearing us anymore.:D
  7. Herman
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    Herman Senior Member

    too bad, I know of a Belgian boat that was filament wound. I believe it was a Mini Transat. (6.5 meter)
  8. tunnels

    tunnels Previous Member

    Theconcept of filament winding could be achieved but the method used is the problem !!
    Also the glass strands orientation of the glass not only on the hull but what about the deck . or are we talking about a deck-less boat ??
    Its possible rather than spiral winding to simply use unidirectional glass and lay it into a mould and do it that way you would have much better control of the materials and you could incorporate a core into the making so even better !!, racing boats have just a thin-skin plus uni-matts placed where its needed under and over the core and then another thin skin on the inside of the hull so cant understand any advantages of spiral winding a boat at all !! as for having continuous strands running over the whole boat every where there got to be weakness some where specially in the widest mid sections and the ends must be over build where all the layers converge into a smaller area . . Sorry it would never be a winner method and become popular that's for sure !! . :(:p
  9. Sail Nut
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    Sail Nut Junior Member

    You may be thinking of crude filament winding

    The state-of-the-art in filament winding is 6 axes numerically controlled, with the winding path designed in detail by computer. Your comment refers to spiral winding, which is the filament equivalent of the rotary phone. With 6 axes of control, the angle to the winding axis can be very small, producing nearly the same effect as unidirectional mat laid along the axis.

    Filament winding allows for much more detailed control over the orientation of the fiber and thickness than unidirectional mat, higher fiber density, and more even distribution of resin. The fibers are somewhat longer than is feasible with mat, but that isn't the main advantage. The process lends itself to much more automation than laid mat. Since the fibers used are processed in the same way as those for unidirectional mat, I don't see any reason for the selection of fibers to be any less than for mat and they should be somewhat cheaper.

    You've got a good point about sandwich construction, which I've never seen used in a filament-wound structure. I don't see any fundamental barrier to winding the inner skin, then attaching the core, then winding the outer skin. Hecka engineering challenge though, to work out all the details, including curing and finishing the surface.

    I think the usual practice is to wind the "deck" in the same pass as the rest of the hull, although the sharpish edges considered normal in a hull-to-deck joint are tricky to wind over.
  10. rxcomposite
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    rxcomposite Senior Member

    There are hundreds of thousand of aluminum honeycomb cored, double walled fuel oil tanks made. A sensor is placed in the core so that any fuel oil breach in the inner wall is detected. The outer wall is a secondary defense against the fuel oil leeching out.

    Filament winding process is great for uniformly loaded pressure vessels with "soft" radius because the filaments are;

    1. In Tension
    2. Continous and unbroken
    3. The process lends to near minimum resin loading on fibers

    It works on driveshaft too because the load is in torsion. The optimum helix angle of wound is calculated to arrive at the designed tensile load.

    How woul you treat the sharp corners on transom, deck to hull corners, and keel joints in boats? Add to that the fact that the outer shell of the boat is almost always in Compression?
  11. tunnels

    tunnels Previous Member

    rxcomposite I totally agree !!
    I don't care if the machine has 5 computer and a dozen axes to wind with the ends are much smaller that the middle and some where all this filaments have to overlap and go and cover that wide and narrow part of the hull and if you cock up and missed how yachts should be built and where all the stress loads are and that weight is critical and to much glass continuous of in short lengths means weigh that's not needed !!
    Show me on paper !! prove it beyond the shadow if a jumbo jet that it can work then I will be a believer !!BUTT until then !! sorry !!
  12. pipe dream
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    pipe dream New Member

    I have a similar idea but i think most of the arguments against this type of boat building are not valid.

    use a pipe factory for a one off power multihull
    vaka keel is cylinder cut in half
    freeboard of vaka and akas is a much larger cylinders with filament wound frames ,,cut in half and flipped over glassed to vaka. ama could be another small pipe.
    not saying the whole boat can be done but 70% of the structure could be done in 3 pieces..

    please let me know anyones thoughts???
  13. srimes
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    srimes Senior Member

    Oh, I don't know about that. This model looks affordable ;)

    Just kidding of course. Great idea for simple shapes like pipe. I used to work for a company that made fiberglass pipe and fitting. It can be good for scuba tanks and rocket nose cones, which is why we couldn't take our fitting winding machines to China. Not that they don't have the tech, but that's the law.

    It'd work for pontoons, or a sub, or an airplane fuselage. Best fit on a boat is mast and spars. It's possible to get very high glass/resin ratios. 75% glass was normal for us, so the strength properties were high as well.

  14. pipe dream
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    pipe dream New Member

    we would just buy the egg not the goose.......get the pipework done in an existing 4 axis mandrel factory and cut in half for large multihull keels, and lager pipes cut in half and turned over for the freeboard off keel and wing deck
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