Sailboats

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  • in reply to: Model Database #39405
    Sailboats
    Participant

    I have the same question, maybe we should send the files to the administrator?

    in reply to: Importing xyz #38119
    Sailboats
    Participant
    in reply to: Create a listing hullform #36524
    Sailboats
    Participant

    Absolutely amazing job, Jurgen! thanks!
    Just a cup of hints in DS:
    – Activate the “Coef based in actual dimensions of submerged body” option.
    – Deactivate the “Default at 0.5*L” option of the Midship location, and fix it at the real “x” position of your maximum immersed area (check your curve of sectional areas).
    – To do a proper curve and locate the real maximum immersed area, you must deactivate hydrostatics from all layers but the hull (or Canoe Body if you prefer).
    Then you’ll find your Cp is too high, I would try a bit more Tc shifted to bow.
    There is a hinge at 1/4 from stern, it reminds me an IMS yacht. IMHO, that shape will reduce planing capabilities, I would try a smoother transition there.
    Thanks, it’s a beautiful boat!

    in reply to: Create a listing hullform #36521
    Sailboats
    Participant

    Jurgen, very nice work with that 40feet cantingkeel! I only suggest you to check the spreaders distribution 😉 .
    Delftship free can perform heeled hydro but in a very basic way, and it will NOT do it over a range of heel angles, so the job can be done but being very patient. What I do usually is a simplified model having just the heeled hull and a 3Dpoint showing the CG position. All I do is rotate over “x” (heel), move up and down and trim (rotate over “y”) until CG vertically fits CB while displacement remain unchanged. Anyway, check this post for a Cp issue that DS shows when calculating hydro in symetrized objects:

    http://www.delftship.net/delftship/index.php/forum/hydrostatics-and-stability/3141-delftship-free-heeled-hydrostatics-fail-computing-cp#3141

    Sailboats
    Participant

    Thanks Icare, I’ll give it a try.
    About the Cp issue, I found it’s not related to heeling hydrostatics but to Symetry.
    I made an horizontal cylinder, half inmersed, and unchecked the symetry box (in order to avoid volume duplication). Cp should be 1.0, but Delftship shows 0.5
    I wonder if Delftship Pro shows the same issue.
    Cylinder attached

    in reply to: Same X and Y scale #36127
    Sailboats
    Participant

    Calcagni, the files that you saw at boatdesign.net were made by myself using Delftship (based on Francois Chevalier drawings), they are not original files from Raison. As so, they are just speculations, anyway they show the essence of the concept as mentioned and detailed on that post.
    What Raison has done is just a scow, an old and very fast concept used for a long time in sheltered and flat waters all around the world. Raison’s originality resides in using it in open waters, where a scow is supposed to be slow because of his poor capabiliy to cross big waves without bouncing, and his big resistance to manage chop.
    I don’t see this hull as a tank trimaran, but just as a tall scow.
    I don’t see any problem on scaling down the 747. If you forget the idea of doing a “true” model with his true LOA/DISP, rig, sails, keel and rudders, and if you take care of the IOM rules, certainly you will achieve the same advantages and disadvantages as the 1:1 boat. It will plane easily and fast, but will perform a bit poorly against the wind.
    Good luck!

    in reply to: Same X and Y scale #36122
    Sailboats
    Participant

    Calcagni, I don’t understand how can I help you…
    I’m not a NA also, by the way, so don’t take my thoughts as accurate info…
    What data seems to be forced for you?
    When scaling down to 1m you will not find the same behavior because of the different incidence of water viscosity in total resistance, basically to reach the same Froude number you will need:
    -more sail area
    -more weight on ballast to stand the bigger sails
    -bigger fin area to compensate the bigger side-force
    -all this leads you to a bigger total displacement
    Check the Doug Lord’s scow models, he has a lot of experience in scaled down RC models.

    in reply to: Same X and Y scale #35169
    Sailboats
    Participant

    Thanks Klaus, finaly I learned how to use it. Perhaps Martijn could add a cross box to this switch and make it easier to understand and use.
    Regards

    in reply to: open with freeship #35107
    Sailboats
    Participant

    This should work: export it as .dxf mesh, import from 3dstudio and export as .wrl (3dstudio or any other 3d software cappable of exporting .wrl). Freeship opens .wrl without problems.
    Anyway, delftship free is easier and faster than freeship (and better good looking).
    Freeship, on the other hand, has a few more capabilities.

Viewing 9 posts - 1 through 9 (of 9 total)