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I build a tool for designing (like Sailcut 8)

  • 08 Mar 2020 14:12
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    Reply # 8808874 on 8769479
    Anonymous member

    I have used LibreCAD https://librecad.org/ for sail design. LibreCAD has a function where the area of any given closed polygon can be computed using the shoelace formula (https://en.wikipedia.org/wiki/Shoelace_formula). I have added code for computing the centroid as given in (https://en.wikipedia.org/wiki/Centroid). I hope to get it included in a future distribution of LibreCAD. In the meantime, I can supply the modified parts of the source code (GPL) to anyone who whishes to build his/her own version of the program.

    Last modified: 08 Mar 2020 14:35 | Anonymous member
  • 28 Feb 2020 16:20
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    Reply # 8781896 on 8769479
    Anonymous member

    Thank you all for the kind words.

    Mark wrote:

    I would like to add it to our useful links section of the website, of course, but I also wonder if it would be possible to reproduce it in its own page on the website too?

    That is a good idea, and it should be possible. It is just JavaScript and HTML. It can also be downloaded and used without internet connection. After cleaning it a little bit up I will upload it to github. So anyone can use it without depending on me hosting it.


    Arne wrote:

    ·         The resulting sail area of each panel should be presented, not only the total area.

    This shouldn't be a problem.

    ·         The other is that some helping lines would be very useful when lofting the sail panels. Remember, the sail has to leave the pc at some stage to be constructed in canvas.

    I thought about the possibility to export the sail as .dxf file to import it with any CAD. But I haven't evaluated this so far.

    ·         Finally, there is the matter of camber. I always nag about camber...

    I agree with that. The tool should put out the complete sail with camber. But I don't have experience with cambered sails so I need to think about the topic a little bit more. Second with having curves and not just straight lines in the drawing everything gets more complicated with programming. So I definitely would like to implement that, but it will take some time.


    Frank
  • 27 Feb 2020 20:27
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    Reply # 8776968 on 8769479
    Anonymous

    Brilliant work Frank, and thank you so much for sharing.

    I would like to add it to our useful links section of the website, of course, but I also wonder if it would be possible to reproduce it in its own page on the website too?  Full credit would, of course, be given!

    Many thanks,

    Mark
  • 27 Feb 2020 18:55
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    Reply # 8776746 on 8769479
    Anonymous member

    Unreal Frank! Great stuff that you offer this to the public domain!!!
  • 27 Feb 2020 16:26
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    Reply # 8776442 on 8769479
    Anonymous member (Administrator)

    Hi Frank,

    I think your version is better than the Sailcut 8.
    However, I still miss a couple of details, which I am sure you can fix:

    ·         The resulting sail area of each panel should be presented, not only the total area. I have found it quite useful to design my sails with just about the same sail area on all the panels, regardless of the sail's aspect ratio. This has proven that I can use the same sheet setup (‘Johanna-sheeting’) on any of my sails (ranging from AR=1.87 to 2.15), and still get right twist in the sail.

    ·         The other is that some helping lines would be very useful when lofting the sail panels. Remember, the sail has to leave the pc at some stage to be constructed in canvas.

    ·         Finally, there is the matter of camber. I always nag about camber...

    I ended up designing a stack of master sails, where the batten panels are within 3% in sail area, and with the needed helping lines in place. See Chapter 4 of  “The cambered panel Junk Rig".
    Good luck!

    Arne


    Last modified: 27 Feb 2020 17:37 | Anonymous member (Administrator)
  • 26 Feb 2020 15:30
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    Reply # 8771543 on 8769479
    Deleted user

    Looks great, Frank. I don't need it at the moment....but when I do......

    Matthew
  • 25 Feb 2020 18:26
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    Message # 8769479
    Anonymous member

    I remembered lately how many times I fiddled with Sailcut then exported to CAD to draw the mast line, calculate the centroid and start over to put the CE again a little bit front or aft.

    So I wrote a tool this weekend to save me from some of that in the future:

    https://jrd.findingdryland.com/

    I would be very happy if this could be a help for someone. If someone has a idea which features could make this more useful, please let me know! I'm not that skilled with math and programming but I would give it a try ...

    Frank
       " ...there is nothing - absolutely nothing - half so much worth doing as simply messing about in junk-rigged boats" 
                                                               - the Chinese Water Rat

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