Wavepiercer Trimaran design -- Azzum / C3NZ

Discussion in 'Powerboats' started by GaryJones, May 7, 2017.

  1. GaryJones
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    GaryJones New Member

    Hi all,

    This is my first post so be gentle. I am interested in what your thoughts are on this design:

    'State of the Art' 12m Wavepiercer Trimaran - Azzum is a wave-piercing trimaran that ... - SeaBoats http://www.seaboats.net/state-of-the-art-12m-wavepiercer-trimaran-xidp625065.html
    2010 Trimaran Wavepiercer Trimaran, New Zealand - boats.com http://www.boats.com/power-boats/2010-trimaran-wavepiercer-trimaran-5776020/#.WQ-DIbv1AiE

    I am not interested in this particular boat but the long skinny hull design for efficiency does interest me. The things I felt were strange from the first link are:

    a> They had inboard engines as part of the initial design but threw them out and went for outboards. Do you think this would indicate there was a problem with the initial design? If my memory serves, Earthrace had those large fins off the back as well and I think they were for oxygen for the engines? I assume they are now obselete?

    b> Water ballast as part of the design? Was that included in Earthrace or any other trimaran of this type? I haven't heard it mentioned before. I thought the general idea for this type of design was to keep it light and efficient like ILAN Voyager -- which I love?

    I am much more interested in this sort of design and its suitability for slow speed (under 10knts) cruising, but when I saw this version of a wavepiercing trimaran those anomalies aroused my curiosity.

    Thoughts?
     
  2. Ad Hoc
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    Ad Hoc Naval Architect

    Look at the length, it is only 13m. Ilan Voyager was 21m....thus, not much room for inboard engines with a hull form that has a very high ( or should be) length-displacement ratio. Which is the raison d'etre of the stabilised monohull. Thus outboards make perfect sense if you want high speed..since inboards, no room in the hulls!
    Ballast can be for several reasons. I suspect that with such a short length and packing in so much, the trim, or rather the LCG was not sufficiently stationary (relative to midships) to provide the best resistance profile. Since these high LD ratio hull forms run best with the LCB/LCG in one location. Thus having ballast tanks, allows flexibility in the arrangement owing to the short length of the design. More so if the LD ratio is not what it should be!

    However, i should point out that the design you linked, does not have a high LD ratio. It is only 6.5. Whereas Ilan Voyager had an LD ratio of 12.2
     
  3. BlueBell
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    BlueBell Ahhhhh...

    Interesting concept.
    What would you use it for?
     
  4. GaryJones
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    GaryJones New Member

    Thanks for taking the time to respond Ad Hoc.

    The inboards must have at least fit as they are in the video below. Perhaps the performance wasn't enough and larger engines would cost too much or not fit? It also appears to plane more than displace. Was this the case with the ILAN Voyager / Earthrace etc?



    With regards my interest. Very theoretical at the moment but I am curious what hull form would work best for solar electric cruiser. It would either be a catamaran similar to Solarwave (which I find a little dull) or something similar to ILAN. I haven't made a full SOR and it is purely an intellectual exercise at the moment as I don't have the funds for the project. My feeling from my limited research suggests approximate speeds of 5knts over 24 hours with power available for short bursts slightly over 10knts. Obviously this is without running the numbers but is more from what has already been achieved.
     
  5. Ad Hoc
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    Ad Hoc Naval Architect

    "...Was this the case with the ILAN Voyager / Earthrace..." (sorry no idea how to quote you directly with this new website layout???!!!)

    Nope, these were high LD ratio hull forms, they don't plane. They are displacement hulls. You just need a high LD ratio hull form, the rest...is simple.
     
  6. GaryJones
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    GaryJones New Member

    I 100% agree with you. Keep it light, keep it long. That is the simple rule for this kind of vessel, but the youtube video has the front 40% of the yacht out of the water and that was before the move to outboards (and probably bigger) engines.

    Anyway, I appreciate your insight Ad Hoc.
     
  7. TANSL
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    TANSL Senior Member

    Well, it's not difficult. Just hit "Reply" :)
     
  8. Boat Design Net Moderator
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    Boat Design Net Moderator Moderator

    Have adjusted the Reply link on each post now so it reads Quote+ Reply.
     
  9. Ad Hoc
    Joined: Oct 2008
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    Ad Hoc Naval Architect

    Now that makes sense!

    Sorry occupational hazard, i like proper QA and consistency with terms! How is one to know....reply means quote of old?
     

  10. TANSL
    Joined: Sep 2011
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    TANSL Senior Member

    Many have been able to find out but, of course, it is now clearer.
    Maybe I'm wrong but I seem to remember that in the previous version there was only "Quote" and that meant "Quote + Reply" :)
    Of course these changes, which undoubtedly are an improvement that we must all thank, may induce, at the beginning, some misunderstandings.
     
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