Biplane Rigs

Discussion in 'Multihulls' started by spidennis, Feb 14, 2012.

  1. spidennis
    Joined: Feb 2007
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    spidennis Chief Sawdust Sweeper

    I got a design for a beach cat that uses a biplane rig and want to know more about this way of sailing. So this thread will be for anything and everything about the biplane rig, types, materials, techniques, pros vs cons, etc, etc.
     
  2. Stumble
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    Stumble Senior Member

  3. spidennis
    Joined: Feb 2007
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    spidennis Chief Sawdust Sweeper

    That is a very cool link, thanks!

    as the author writes:
    "Even the guy who built the boat, Ian Morse, is still unraveling its mysteries."

    I'll be digesting this read for quite a while, and especially when I finally start sailing mine!
     
  4. yipster
    Joined: Oct 2002
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    yipster designer

    Great, still very interested, also check the search button above as I and others started similar treads that showed various biplane boats. Even drew one up, check ladybird in my gallery. Various aspects were discussed but general conclusion undicided, more like: "it al depends"
     
  5. spidennis
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    spidennis Chief Sawdust Sweeper

  6. hausmuzik

    hausmuzik Previous Member

  7. P Flados
    Joined: Oct 2010
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    P Flados Senior Member

    Greg Ketterman really liked the biplane config. Given that he got a world record with Trifoiler, the format can do quite well.

    For a cat, a biplane can really help achieve structural requirements with lighter cross beams. However, this need to be built in when the boat is designed.

    The extra cost/complexity of two complete rigs is the biggest downside.
     
  8. tugboat

    tugboat Previous Member

    Berhnd Kohler- either invented the biplane rig or innovated it..they are fast -faster than a single master...they need to be spaced quite far apart for it to work- yves parlier was the first to really bring it into modern technology..although one of his masts is offset and not on one of the ama's.

    expect to see this possibly used on trimarans...

    also this coupled with anti-vortex panels makes for a very fast boat--try looking up Bernd Kohlers site...i bought a set of plans from him--not a parallel rig but he has a write up on them on his site--lately i haven't been able to access it. wonder if hes gone bust?
    but try http://www.ikarus342000.com/CATpage.htm

    not sure why it wasnt working...

    i bought the p95 31 ft cat. plans
     
  9. spidennis
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    spidennis Chief Sawdust Sweeper

    here's some biplane examples:
    (and I know I missed a bunch of them)

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  10. spidennis
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    spidennis Chief Sawdust Sweeper

    tug,
    There is a yahoo forum that is quite active where Bernd is quite helpful. I've been both on his forum and emailing him directly this past week. You'll see some of his examples in the photos I've posted.
     
  11. tugboat

    tugboat Previous Member

    yea- i got a set of plans from him--great design..simple and effective... i am on there too-from time to time-but involved in a tugboat build--there might be issues regarding the land im building on which puts my project in jeapardy and if that goes south--ill build the p95...
    who is the designer of your beach cat? ill read some of the posts on here..good thread...
     
  12. spidennis
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    spidennis Chief Sawdust Sweeper

    Who's the designer? ME! eek!!! So it's gonna be trial and error but up to this point mostly research, tons of it. The requirements finally molded my design. I still got lots to work out, and more as I build my first 1:1 working scale model using an old beat up Prindle16. The last pic is mine btw. I am now working with a designer that is doing the hull shaping. It seems I can't find just the right thing and any designs that I use, such as the F16 Blade I'm gonna have to modify anyway so it's time to get what I want. I'll do the build in my garage.
     
  13. rattus
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    rattus Señor Member

    The biplane rig should be quite effective on very fast multis, where the AWA is always well forward of the beam. Yes, there are two of everything, but now the masts are (usually) in the hulls, smaller with inversely proportional loads, beam engineering requirements are much simpler with lower loads, and the CoE and capsize moments will be a fair bit lower.

    It's just gotta be fast. What's not to like? ;-)

    I also suspect it would be darn near impossible to build folding beams (like those on Cat2Fold) if you had to engineer in loads for a single mast.

    Mike
     
  14. spidennis
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    spidennis Chief Sawdust Sweeper

    Mike,
    Initially the cat2fold boat was a single stick but I gather they found out just what those loads were in real life?

    So far I like everything the biplane rig is on my design except I need two masts and sails, and somehow to control the lines.
     

  15. rattus
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    rattus Señor Member

    Dennis, you are right, that seemed to have been the original plan.

    I think the only way they could have made a single mast work would be if it had been unstayed and supported by some sort of bracing, as it is open-decked. If it had been stayed, a lot of downforce on the folding bearing probably would have required massive (and heavy) reinforcement on the beam and bearing.

    Are you considering a wishbone boom? That would take care of vanging, and drop the mainsheet loads down possibly to a point where you wouldn't even need winches, just tackle.

    Mike
     
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