Small trimarans under 20'

Discussion in 'Multihulls' started by Doug Lord, Jun 24, 2012.

  1. Cholsson
    Joined: Aug 2015
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    Cholsson Junior Member

    Perfect trimaran building weather

    Swedish summer is perfect for building your trimaran. Rain Rain Rain :)
    Starting to put things together now. A small around an island race in two weeks I will try to be ready for.[​IMG]

    Maybe I have built it too big for the garage?

    www.chryz10.com

    Chris
     
  2. upchurchmr
    Joined: Feb 2011
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    upchurchmr Senior Member

    Chris,

    That is a great looking Tri so far.
    Do you have plans?
    I've been looking for something similar to build.
    18' is about the limit for my garage, similar to yours.

    More pictures?
     
  3. patzefran
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    Location: france

    patzefran patzefran

    Nice looking, but do you really think the beams will resist any wind ?
     
  4. Cholsson
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    Cholsson Junior Member

    Some more pictures and info at my blog, www.chryz10.com
    You will see how it survive wind and sails.
    I will put on my action camera when I test-sail.
    Last year it was some epic failor with the prev boat.. but it was exciting :)

    Chris
    www.chryz10.com
     
  5. Munter
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    Munter Amateur

    Those beams do look awfully small compared to their length. Presumably you have water-stays and other braces to help keep the platform in its original shape?
     
  6. patzefran
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    patzefran patzefran

    Anyway, the available height for waterstays is so small that you will get very high tension/compression loads, even if you attach them below the waterline.
    DIY tris, like Kayak tris need very small rigs or they collapse !
     
  7. Cholsson
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    Cholsson Junior Member

    The waterstays will be amazing!
    Maybe too sweet and durable compare to production boats!
    [​IMG]
    [​IMG]
    The rig will be huge. 8 meter (26 feet) carbon fiber. Nothing will collapse.
    Maybe my blog will collapse by all visitors ;)

    Chris
    www.chryz10.com
     
  8. patzefran
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    patzefran patzefran

    It looks better altough waterstays attachment are close, if not under the waterline. perhaps a wet ride !
    Assuming a 120 kg boat weight , a single 80 kg crew sitten on the windward hull and 3.7 m between outrigers centerlines, when lifting mainhull, your righting moment is roughly (120*3.7/2+80*3.7)=518 kg.m. You have to pass this moment thru beams and waterstays hull attachment. assuming 0.3 m height between attachments and beams, this gives a 518/0.3=1727 kg total compression on the beams, and about 1800 kg tension on the wires, mainly on the most forward wire / beam.
    I hope you ran some computation and your domestic aluminium stair and wires will sustain this ! don't sail with 2 people onboard.

    My Strike 15 as also a 8 m carbon mast for 15 ft hull length, it is not huge at all. Beams are 80 mm carbon tubes and waterstays use two 6 mm vectran lines under each beams. On my Strike 20 I use 100 mm OD x 3 mm thick 6061 T6 aluminium tubes together with four 6mm vectran lines under each beams, highly pre strained, which I have found was just enough ! Both sails successfully with no failures.

    Wait and see ! I will be curious to see your trials.
    Good luck anyway.
     
  9. Cholsson
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    Cholsson Junior Member

    It's out!

    [​IMG]
    [​IMG]

    Assebly my tri outside today and raised the mast. Finally!!!
    Wanted to test the main sail, but its too windy right now :)

    Chris
    www.chryz10.com
     
  10. Munter
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    Munter Amateur

    Just a thought - did you make the waterstays somewhat continuous through the main hull? It would seem structurally advantageous not to require the hull to carry the tension but instead run it through a specific element which spans the hull like a short rigging wire or similar.
     
  11. Cholsson
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    Cholsson Junior Member

    Hi! Yes, its exactly what I have done, and you can also change the tension. Dont know the english word for that hardware, but here is a how it looks like inside.
    [​IMG]

    Will add some more photos today. Have done a lot for the furling and sail system the last couple of days.

    Chris
    www.chryz10.com
     
  12. Munter
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    Munter Amateur

    I can't quite tell but it looks like a bottle screw in there - which is exactly what I was thinking of. I think the other name that it could be given is a turnbuckle.
     
  13. Cholsson
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    Cholsson Junior Member

    Ah ok, turnbuckle. Ok here is a brighter one from the most forward water stay
    The hull is reinforced with fiberglass, and all water-stays fasten with carbon fiber-plate reinforcement you can see on the photo
    [​IMG]
     
  14. patzefran
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    patzefran patzefran

    Looks like 3 mm wire and 6 mm shroud adjuster, breaking load around 820 kg , max safe working load around 260 kg. If you compare to a standard catamaran dolfin striker it seems a little light
     

  15. patzefran
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    Location: france

    patzefran patzefran

    OK, I was talking about the exterior wires and turnbuckles !

    I would use inside some loops of vectran or other aramid, much lighter and load carrying capabilities. As I would change exterior wires and turnbuckle with vectran loops tensioned by lashing around two friction eyes. I experimented this on the strike 20 and it is much lighter / stronger than Stainless steel.
     
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