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Junk Rig Calculator

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  • 26 Oct 2013 13:48
    Quote
    Reply # 1421747 on 1420814
    Anonymous member
    I don't mind at all if the thread is moved. But I'm a bit sceptic about spreading all kinds of different forums all over the site, there should be a root directory listing all the sub forums, in my opinion. But that's a whole other discussion which belongs somewhere else.

    I've added the Johanna sail and made a bunch of small tweaks to the calculator.

    Complete changelog can be found here.




  • 25 Oct 2013 20:01
    Quote
    Reply # 1421347 on 1420814
    Deleted user
    Oscar et al... How about we move this fascinating project discussion into our new Projects Fora? It's the ideal place. Give it some thought and either I'll move it next week (am going to be offline for a few days) or perhaps Lesley who will be covering can.
  • 24 Oct 2013 23:50
    Quote
    Reply # 1420840 on 1420814
    Anonymous member
    I made up spreadsheets to calculate the dimensions of both Johanna (Arne's) and Fantail (David's) rigs. I forget where I put them now (I just sent them to you in an email), but you just enter your desired sail area and you get all the measurements of your panels. With displacement it will give you some mast recommendations also. It would be nice to expand them to include material and rigging warrants as well, I find that part usually confusing (translating a sailplan into meters/yards of cloth and webbing and line). It's a lot more spreadsheet work to have variable aspect ratios as well. 

    You could translate the spreadsheets into your calculator or upload them into a public google calc page. 
    Last modified: 24 Oct 2013 23:59 | Anonymous member
  • 24 Oct 2013 23:27
    Quote
    Reply # 1420816 on 1420814
    Anonymous member
    Oh, and everything is metric instead of imperial, which reflects my personal view of how dividing things into 10/100/1000 is much more logical than using fractions.

    That said I'm likely to implement a unit switching feature at some point, given that someone is interested in this.
  • 24 Oct 2013 23:22
    Quote
    Message # 1420814
    Anonymous member
    A little project I've been working on the last two days:


    Some people prefer spreadsheets for these kinds of things but I usually go on the web searching for them, so I thought I'd put them all in one place.

    Calculations implemented so far:
    • spars (mass and breaking strength of hollow, solid, straight and tapered spars)
    • hull (sa/disp and disp/lwl)
    • spar dimensions according to sail type (idea blatantly stolen from Karlis Kalnins)
    The user interface hasn't been given much thought yet, and it will soon become bloated if/when features are added. Some kind of menu system will probably be implemented.

    I also have some issues with calculating breaking strength of tapered spars, as pointed out in this post. For now I've simply settled for using 95% of the base diameter as a base for calculating the breaking strength, given it should be somewhat close to the diameter at the partners. Thinking about it now, 90% would probably be better (given the usual 10% bury).

    Any suggestions/additions/questions/ideas are welcome. Source code is hosted on Bitbucket (it's written in Javascript in somewhat of a haste over the last two days so formatting/comments isn't up to par but it should be readable).
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       " ...there is nothing - absolutely nothing - half so much worth doing as simply messing about in junk-rigged boats" 
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