CNC Plans not Included

Discussion in 'Multihulls' started by jorgepease, Sep 19, 2016.

  1. brian eiland
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    brian eiland Senior Member

  2. brian eiland
    Joined: Jun 2002
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    brian eiland Senior Member

    Good advice being offered on some of these latest postings. I can remember now a problem that occurred on the big Polish catamaran that entered that first 'RACE' around the world. It had to add diagonal cabling under the tramps between the fwd and aft crossbeams to obtain a better stiffness. (can't find that reference link at the moment).

    But here is another discussion I started on that subject
    X-Beam and the Giant
    http://www.boatdesign.net/forums/multihulls/x-beam-giant-14679.html
     
  3. brian eiland
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    brian eiland Senior Member

    BTW, before you get set to accept those 'protuberances' into the wing deck areas to provide lower-bigger berths in the aft end of the vessel, take a look back at the old Prout designs that included such an item,...and the problems/complaints experienced.
     
  4. brian eiland
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    brian eiland Senior Member

    Vessel Substructure to Support Rigging Loads

    Ah ha, I found this older posting (wonderful google search assistance)

    http://www.boatdesign.net/forums/sailboats/sail-loading-rig-rig-loading-vessel-2293-4.html#post114487

    excerpt...
     
    Last edited: Apr 21, 2017
  5. brian eiland
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    brian eiland Senior Member

  6. jorgepease
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    jorgepease Senior Member

    Look at this catana, those bunk shelves look like they might slam. Aft I think it's less likely.

    How high would you say the shelf is from the water in this pic? Looks much lower than what I am drawing.

    [​IMG]
     
  7. jorgepease
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    jorgepease Senior Member

  8. brian eiland
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    brian eiland Senior Member

    For a lean/mean fast machine you are going to have to spend more than i think you plan on budgeting,...for both hi-tech hull materials, and hi-tech sailing rig equip. And you better plan on spending 2-5 years building it.

    On the hand you could buy one of these, go off for some delightful sailing (perhaps a few knots slower), have some wonderful experiences exploring the MED, perhaps meet some wonderful ladies that would love hanging out on this vessel, and then turn around and sell it for a reasonable amount of money if you kept it in good shape. And I think this vessel has as much, if not more, room and amenities on it than what you are trying to put into yours.....just saying.

    I would term that a 'raised helm station' rather than a flybridge, and I think you would come to really appreciate it. You need to go charter a few different
    big cats to get a first hand look.
     
  9. brian eiland
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    brian eiland Senior Member

    It's a little hard to tell from the dark shadows and the waterline, but I would venture to guess she is in a light-ship condition as it appears she is floating well up from her painted waterline. My guess is those protuberances are about 18 inches above the water at this point, and might go down to only 12 inches clearance once she is loaded up for cruising. It's their 'flat bottom surfaces' that bother me most,...that is a recipe for slap. I don't want any surfaces in that under bridgedeck are to be perpendicular to water impingement.

    Maybe go on line and fine some owners of that design, and she what they have to report,...first hand info.

    Here is a little discussion and a few photos from Richard Woods...
    http://www.sailingcatamarans.com/index.php/faqs/19-sailing-and-performance-questions/108-bridgedeck-slamming
    ...and by the way those early Prouts had a tendency to pitch quite a bit as a result of their 'dbl-ended hull shapes'
     
  10. jorgepease
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    jorgepease Senior Member

    I did, they were complaints about it. I figured 18" too. Mine are about 36" above the waterline.

    I just read that thread on the bending stresses, interesting, now I understand some more of the forces at play.

    I think my bridgedeck is going to help a lot in that respect. By separating top and bottom panels and adding stiffeners in between it's going to be like a giant Ibeam and that stiffness has to be transferred to the hulls as best possible.

    The upper and lower panels should be separated a minimum of 4" and the stiffeners have to run longitudinally.

    Additionally I am thinking about the torsional forces that were mentioned. I am thinking that I can add that short return (enclosing salon) as first drawn with a beam that spans the space. This would be a carbon frame that would enclose very little but could help with the torsional support and tie in the roof as already mentioned, needs more support.
     
  11. jorgepease
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    jorgepease Senior Member

    It has more amenities I think :D

    The thing is what am I supposed to do for the rest of my life? A charter fleet is a perfect life style that will support me and allow 4 months per year to sail and fiddle around with innovations for years to come.
     
  12. groper
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    groper Senior Member

    The type of boats you see in charter fleets are like the boat shown in brians video. Thats what the industry wants, not high performance sailboats.... if thats the industry you want to be in jorge- then this boat you arw designing should be a floating palace- not a performer...

    My needs and wants are very different to a charter guest. For me, i want a boat that can eat up hundreds of miles per day witg very good sailing performance so that i can cross oceans to get to new places all over the Pacific on an extended cruising adventure.

    A charter guest im the med doesnt need ro cover many miles... they only have a short time available and just want to relax in comfort sippint cocktails and putting up their photos on instagram showing off to their friends back home. They want luxury. Most of them dont know how to sail or trim a sail.... they spend alot time motor sailing...

    So you need to think carefully about what your designing Jorge....
     
  13. jorgepease
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    jorgepease Senior Member

    I have already thought about the business side of it. I don't want to cater to the masses, and there are quite a few SIG45's out in charter so I don't think I'm straying too far from the model. My craft will be much more luxurious than the SIG.

    Also my angle is eco adventure, zero carbon footprint, this is at the peak of interest these days. )) and I can do some pretty beautiful things with my hands that I can't do on the computer. That is why I at least need a large topside.

    And then after charter season, I'l be wanting to cover some miles myself.
     
  14. waikikin
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    waikikin Senior Member


  15. jorgepease
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    jorgepease Senior Member

    I checked it out, can't see from the front angle but I wonder why the 45 to the shelf? must be for a chase?

    Anyway I decided to raise it a bit to be on the safe side, now my shelfs will be at 39" above waterline and rest of BD will be at 53.5 above waterline... It will raise interior bunks to 33" and I will see about the sheer but I think it's okay where it is.

    [​IMG]

    [​IMG]

    [​IMG]
     
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