Small trimarans under 20'

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

  1. upchurchmr
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    upchurchmr Senior Member

    You must not be remembering a small cat. You can call a person on a trapeze a "standing" crewmember but if you have enough wind you will have a lot higher performance from increased righting moment than you will have due to an increase in drag.

    If your entire boat is too big and underpowered enough to not get a benefit from trapeezing then I would agree with you.

    The only thing I don't like about Akila is the obvious fact that the ama's are small enough to not be able to fly the vaka. But that was the design choice made to start with. It would be really fun, on or off the trapeze.
     
  2. oldsailor7
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    oldsailor7 Senior Member

    Yes you are right. All my experience is with multis over 24 ft.
     
  3. Skip JayR
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    Skip JayR Tri Enthusiast

    Eureka isnt just Eureka...

    Using the search function, I found different "topics" related to Eureka, e.g. a Crowther Eureka. And here comes another Eureka for ocean sailing...

    Just like to post a new 20 ft Tri project I fell over in Wooden Boat Magazine. The concept of the EUREKA is interesting as this tiny boat is combined with an "eco friendly" propulsion: a Sea Bike.
    [​IMG]
    EUREKA is a 20′ (6.1m) demountable (“take-apartable”) trimaran suitable for long-distance coastal cruising and adventure racing for one or two. Empty weight is approximately 500 lbs (230 kg), with a payload of up to 600 lbs (270 kg).

    The boat is drawn with an aft “pedaling” cockpit, and a small cabin centered between the akas (crossbeams). Both have steering stations: the first with joggle sticks (or vertical tillers connected to tiller lines or rods) and the latter with foot pedals—kayak style, with one pedal on each side of the centerboard trunk.

    The single berth flat sits directly above the trunk and runs forward, under the foredeck. The boat is completed with a kick-up centerboard and rudder to reduce the chance of damage in the event of grounding or hitting a submerged object, especially at speed.

    The EUREKA parameters...

    LOA 20′ (6.1m)
    BOA 13′4″ (4.06m)
    Draft 9′ to 4′10″ (0.2–1.49 m)
    Weight 500 lbs (230 kg)
    Sailing displacement (half load) 800 lbs (363 kg)
    Working sail area 220 sq ft (21 m2)
    Reaching spinnaker 180 sq ft (16.72 m2)
    Bruce Number* 1.64

    *The Bruce number is the square root of sail area (in square feet) divided by the cube root of displacement (in pounds). It relates power to weight, so is a predictor of potential speed.

    Source: http://www.woodenboat.com/eureka-2

    P.S.: Haven't found yet a video to see the seaworthyness and handling.
     

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  4. Doug Lord
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    Doug Lord Flight Ready

    Thanks, Skip-interesting boat! Not sure Bruce number is a good predictor of potential speed since it doesn't include beam/righting moment. You could conceivably have two boats the same weight ,same sail area with different beams and the speed potential of the wider one would be greater but not reflected in their identical Bruce Numbers.
     
  5. Gary Baigent
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    Gary Baigent Senior Member

    If the Bruce number was over 2 then your beam comment would mean something - but at 1.64 Bn, (that is keelboat territory) and that figure is very moderate, especially with those quite large volume floats.
     
  6. Skip JayR
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    Skip JayR Tri Enthusiast

    So having a 40 foot Trimaran with 60 foot Mast and a bruce number something between 1.8-1.9 is a bad value ? - Should it be >2 to call it a sportive/cruising-racing tri ?

    Gary, are there any sources with lists/tables of "modern" and "old" trimarans to compare quickly the Bruce numbers ?

    Tks in advance of any web link, book source etc. ....
     
  7. Doug Lord
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    Doug Lord Flight Ready

    I think Eric Sponberg has some comparative data here: page 37
     

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  8. Skip JayR
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    Skip JayR Tri Enthusiast

    Thats pritty interesting stuff... many tks, DoughL. Why is life so short ??? If I'd have another 50 years I'd study naval architecture design. I love that... :)

    Scrolling through I found on page 25 an interesting chart which indirectly addresses my question, too. The Sails area / displacement ratio vs. displacement/length ratio. So many tks.
     

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  9. pogo
    Joined: Mar 2010
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    pogo ingenious dilletante

    Skip,

    there ain't no Königsweg, no silver bullet, no royal road, no ideal solution ,
    neither for performance predictiction, nor for safety, fun factor, imdividual satisfaction, or finding the right trimaran.
    Any " judgement" by "selected" second hand knowlegde is not the right way, especially when there ain' no technical background and/or personal experience at all.
    A technocratical way, your technocratical way, is in my opinion the wrong way. You wanna have proved , you wanna have calibrated things , you wanna have brought things that you don' t understand to one ( 1) point.

    There is a lot of fantasy in your thinking about sailing , living and working on a fast trimaran .

    A first try, even on a " smaller object" ( not obligatory in size) is in my opinion the better way.
    Try a Searunner 35/37 for one or two seasons , and then....
    Gaining experience for better knowing what you really need and not what you want now....
    Knowlegde --Know How and Why comes step by step , not via formulas or pix, or via a not handable overkill of info for a rookie.

    One can' t buy the perfect boat the first time.

    pogo




    Sounds like i'm getting old.

    Sorry for a little OT , but i' m pretty nerved ---your massive senseles posts w. pix of boats and things we nearly all know about for decades , your " overwhelming " enthusiasm
    AND your interpretations .
    Für letzteres vielleicht an Nuhr halten, Zitat: " Wenn man keine Ahnung hat, einfach mal die Fresse halten."
    (When you don't know anything, shut up)
     
  10. pogo
    Joined: Mar 2010
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    pogo ingenious dilletante

    Concerning the little tri above,
    I don' understand it.
    It's yrvindesque .
    The smaller the more attempt ?
    What the hell is " long distance coastal cruising " ?

    O.K. Rory McDougall has circumnavigated in a Tiki 21 , we' ve had Tinkerbells a. s. o.
    But.....i think www and ego sometimes generate impossible missions---documentated in blogs , followed by enthusiatic couchpotatoes with pads.

    All those Kapitän Voss's have exploited their really dangerous adventures w. tiny boats --they wrote books.
    Nowadays bloody amateurs are encouraged to do the same--a luxuruy problem of an overfed civilization searchin' for self- affirmation.

    For me , there ain' t no " long distance coastal cruising" which implies overnight trips with autopilot -- sitting in the cabin , navigating trhu the plexi bubble .

    With 20' boats it is really enough to gunkhole , to trip in camping style along a coast, sailing 5-8hrs in daylight.
    Sitting and sailing near the water, sailing live. Fun, sometimes fighting , getting wet, glad to have a dry bunk in a shelered bay/haven at day's end .
    Back to ......where i've started. I've enjoyed this school for ten years , very teaching ten years .
    Fighting in a small boat against " big " but adequate challenges.
    Weniger is' mehr.
    Less is more.

    Stretching to " long distance coastal cruising" means a sort of comfort for sleeping , navigating, cooking while sailing ----things a 20 feet non ballasted centerboarder, cruising dinghy , or multihull can't deliver.




    pogo
     
  11. pogo
    Joined: Mar 2010
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    pogo ingenious dilletante




    This is what i meant with your technocratical , interpretational way.

    Vidiotic Technocracy , hahahaha !!



    By the way,
    what gives you the idea to find vids of a project ?
    Bad , bad , bad investigation.
    Wer lesen kann ist schwer im Vorteil.
    (You show us all disadvantages of a fast, visual orientated nintendo kid and a digital native. quick , quick, quick---pic, pic, pic)
    The real world consists of more than pix and vids that engulf the enthusiasm of .....
    Calm- toi--analyze, investigation is another, more demanding job.


    pogo



    .
     
  12. Skip JayR
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    Skip JayR Tri Enthusiast

    Zeta 14' Trimaran from Richard Woods

    Just found it on Wooden Boats...
    [​IMG]
    The Zeta main hull is similar to the Zest but a bit narrower. It does have a footwell, as indicated by the dotted line running along the top of the daggerboard case. The outriggers can be made from 2 sheets of ply, so you need 7 sheets 4mm and 1 sheet 6mm to build the whole boat. It could certainly be built in a week.
    [​IMG]

    Plans will be available end of November (2015).

    The Zeta is a bit like a 14ft version of the 10ft Duo/Tryst (lots of those building/sailing now BTW).

    Tryst details can be seen here: http://sailingcatamarans.com/index.php/designs/27-trimarans-under-25/428-tryst-trimaran

    Zeta website and study plan (PDF download) here: http://sailingcatamarans.com/index....-under-25/458-zeta-14ft-singlehanded-trimaran

    Video of the Tryst...
    https://www.youtube.com/watch?v=o6T_l8aKP9M
     
  13. Corley
    Joined: Oct 2009
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    Corley epoxy coated

  14. rcnesneg
    Joined: Sep 2013
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    Location: Utah

    rcnesneg Senior Member

    Sweet! It actually looks pretty decent! Is it as fast as a Hobie 16?
     

  15. Doug Lord
    Joined: May 2009
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    Doug Lord Flight Ready

    Astus 16.5

    Really good looking! Looks narrow on the trailer- the crossarms must telescope? Missing that same old same old though.......
    Thanks, Corley.....
     
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