The Aerojunk

  • 10 Feb 2013 00:42
    Reply # 1203699 on 1152568
    I have been looking at Paul's article.  It is an interesting concept but I would need a much taller mast to carry the sail area I currently have, and I think the mast would need to be further aft.  To get his 9m luff I'd need to increase my mast height by at least a metre and I would still only have a 30 sq m sail as opposed to Arion's 36 sq m.  That leads me to think that a square headed main, like a gaff profile, would be more effective on Arion at least.  A lighter boat that needed less sail area might be suitable for Paul's sail plan.  As an old bermudian sailor I do like the look of it - though I wonder about fixing those wishbone battens if they broke.  Being shorter as they go up would make them less likely to break, I think.  I seem to remember that the guy with the wishbone rig on his 46 foot Wharram cat has had a lot of breakages, though his smaller cat was very successful.  I love all these experimental ideas and admire the people who put the time and energy into developing them but I am a bit of a stick in the mud.  I like Kurt's good enough philosophy most of all!
  • 08 Feb 2013 17:46
    Reply # 1202681 on 1152568
    Great to hear that you're starting on a working rig, Paul, and putting it on the Etap23 should yield some useful results. In the end, you just have to make a rig and take it to sea to find out out how well it works. 

    Aesthetically, I like the planform you've drawn, and it gets away from the "pointy-top", which is reckoned to be inefficient in terms of drag. And, as you suggest, getting enough area on a short, unstayed mast is always a problem, and the yard helps with this.
  • 08 Feb 2013 17:34
    Reply # 1202668 on 1152568
    Excellent, Paul! 
    Glad to hear this, and best of luck.
    Kurt
  • 08 Feb 2013 07:52
    Reply # 1202376 on 1152568
    Hi Kurt, Mark, Chris. Thanks for your comments and questions. When I put this design on the forum the initial comments were "interesting but unproved". So after 6 years without a boat I have bought an Etap 23 that I will collect later today. I will be converting it to AeroJunk over the next couple of months. I will photograph all the steps I take and hope to produce interim and final reports on my progress and its performance.

    There will be a drawing of the sail I propose to make in the technical illustrations section. This will be a modified version of my first design to get enough sail area without making it ugly. Because the boat will be for Coastal use I am using a 2:1 aspect ratio.

    I am using 1"x1/2"x1.5mm rectangular aluminium tube that weighs 0.3 kilos/metre. This is available in 5 metre lengths. That makes my longest batten 2.5 kilos in weight. I will be using 5" aluminium tube to make a socket for the 4.5" mast.

    More later, Paul McKay
  • 07 Feb 2013 18:31
    Reply # 1201823 on 1152568
    Hi Mark,

    I think that besides keeping its aspect ratio, a triangular sail keeps its centre of effort forward when reefed. When we reef our junk sails deeply, CE moves aft and, on our schooner, we have to take more out of the main than the fore. We live with it.

    Your point about fractional versus masthead jib might be quite right, assuming there's no mast-bending system at work.

    The Aerojunk has many possible planforms, from imitations of standard shapes, to the downright fanciful!

    The split junk (almost typed 'spilt junk') rig seems a close relative. Aerojunks have an intriguing future, if Paul MacKay and others are able to put the development effort into it, as Slieve has done for the split junk.

    Cheers,
    Kurt
  • 06 Feb 2013 13:50
    Reply # 1200454 on 1152568

    Is not the advantage of a triangular sail that it maintains its aspect ratio when reefed?  In theory may give better windward performance in strong wind.  (I will leave the answer for the experienced junkies out there.)

    One thing I find curious about is the 7/8 jib,  this is for changing sail shape, so not relevant to a junk (or just current fashion)?  Would a masthead jib not be better?

    Mark

     

    Last modified: 06 Feb 2013 13:51 | Anonymous member
  • 06 Feb 2013 05:46
    Reply # 1200189 on 1152568
    Deleted user
    David thank you. I wanted to do so in the first place but had a seniors moment and couldn't find it.

    Have sent an email direct.
  • 06 Feb 2013 02:05
    Reply # 1199990 on 1152568
    Chris, it might be best to approach Paul McKay directly for an answer to your questions, in case he's not looking at this forum. You can find him in the members directory.
  • 05 Feb 2013 21:32
    Reply # 1199728 on 1152568
    Deleted user
    I like this. I immediately printed out this article and can't put it down.

    I have just completed putting a Junk Rig on a small trimaran. Encouraging, however because I moved the mast forward I am getting wishy washy feel on the tiller. By putting this rig in the original mast location it should locate the ce similar to the designer specs's.
    If I can ask a question or two?
    Am I right in assuming that the Main Luff is only attached at the head and the foot?
    Is my understanding right that the "cross-rods" are just a bit of say 8mm rod spaced across the front of the mast?

    Chris
  • 19 Dec 2012 17:56
    Reply # 1163277 on 1152568
    Deleted user
    Sorry Paul this forum is not going to work for me. I am going back to the Yahoo forum!
    Last modified: 19 Dec 2012 17:59 | Deleted user
       " ...there is nothing - absolutely nothing - half so much worth doing as simply messing about in junk-rigged boats" 
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