AeroJunk Update

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  • 04 Oct 2013 21:23
    Reply # 1405071 on 1403598
    Paul McKay wrote:Greetings. 
    I have been able to demonstrate the AeroJunk to 3 different members of the JRA. Now that they have posted their impressions I would like to thank all who have commented upon the rig, especially to Paul Thompson for pointing out a problem I didn't know I had - Parasitic drag.

    All boats have parasitic drag, it's an unavoidable part of generating motion from a sail.
  • 04 Oct 2013 18:46
    Reply # 1404945 on 1399852
    David Tyler wrote: though I have thought long and hard about how the the split rig can be made suitable for offshore sailing, I cannot convince myself that it will be.
    Would you explain what obstacles you see?
  • 03 Oct 2013 00:50
    Reply # 1403598 on 1378058
    Greetings. 
    I have been able to demonstrate the AeroJunk to 3 different members of the JRA. Now that they have posted their impressions I would like to thank all who have commented upon the rig, especially to Paul Thompson for pointing out a problem I didn't know I had - Parasitic drag.
    I might argue that Parasitic drag on a cruising boat is a difference that makes no difference. I might further argue that, considering the wind blows horizontally, my rig with its single-line sheet compares better than the standard junk with its multi-part sheeting. But that would be churlish.
    Many people locally, privately and publicly have commented upon how small/lightweight/undersized my battens appear. It is an acknowledged fact that amateurs tend to over-engineer their creations where professionals pare their scantlings to the minimum.

    I was sailing alone one sunny day in a Force 3 wind when I was hit with a tremendous gust that flattened the boat to between 45 and 60 degrees. I only witnessed the 45 degree bit as I flung my arm over a stanchion to stop from falling overboard. Miranda careered round in her own length to face the wind. This whole scary episode lasted for 30/45 seconds. Afterwards I examined the rig to find it completely unaffected.

    I must say, if I were considering sailing thousands of miles from land, I might be tempted to over-engineer my own battens but the fact remains that my new design, the AeroJunk, has already been tested under conditions that I would never have agreed to.
    Best wishes, 
    Paul McKay
  • 02 Oct 2013 13:06
    Reply # 1403028 on 1378058
    During September we were in Scotland and having previously been in contact with Paul arranged for a sail onboard "Miranda". We were lucky to have a largely fine day to enjoy the scenery but with only force 1/2 winds. (Lucky also because next day the first of the autumn gales arrived and many "Calmac" ferry crossings were not sailing). We were thus able to raise the rig in the marina. Immediately apparent is the well-cambered shape of both jib and mainsail. Paul had modified and simplified the batten design since his first concept article with the jib camber fuller and further forward. Interestingly he too has rigged down-hauls for the lower battens to tighten the jib and mainsail luffs. After leaving the marina (electric outboard!) we sailed on all points achieving over 4 knots at times off the wind. The rig seemed well balanced and changed tack without stalling despite the relative lack of wind. Dropping the rig showed the disadvantage of the shorter upper battens and yard as without the extra weight that a conventional junk rig would have it didn't completely pack down into the lazy-jacks and would require use of a down-haul in different conditions. On the upside, Paul's novel main-sheet arrangement means much less rope underfoot. It seems to control the sail twist surprisingly well too. How much of this is due to the sailplan? Obviously, the present rig is experimental and the batten construction would need 'beefing up' to make it robust for coastal/offshore passage making. Paul has been very inventive with his use of cable-ties to make his battens easy to assemble/dis-assemble while developing his rig. Since I read Paul's first article I was struck by the potential of the concept as an alternative route to achieving camber in a split rig. Our own rig has a lot of sail forward of the mast which is why I have been attracted towards one. Personally I would not want to sacrifice so much sail area (caused by the bermudan type sail-plan) and would prefer a sail with a longer low peaked yard such as advocated by Slieve. None-the-less it seems to me that the aerojunk batten is adaptable to that type of sail-plan but that the main-sheet arrangement would doubtless revert to being multi-part too. Something to work on this winter! Thanks again Paul and looking forward to your next articles in the newsletters.
  • 27 Sep 2013 18:57
    Reply # 1399852 on 1398848
    Johann Ferrer wrote:

    Knowing about this rig, every conversion to a standard junk rig, cambered or not, is simply a big mistake. Even compared to the split rig, I see big advantages for the aero junk rig.

    Thank you Paul for this contribution to the sailing community.

    Johann

     

    Not so, Johann. There still needs to be many different kinds of junk rig for different uses. A flattish junk rig is still the best rig for downwind ocean crossings. Both Slieve's split rig and Paul's Aero junk have been showing great promise as inshore rigs with good windward performance, but that's not the only criterium to judge a rig by. Neither rig has yet been used for a lengthy offshore passage, and though I have thought long and hard about how the the split rig can be made suitable for offshore sailing, I cannot convince myself that it will be. The same applies to the Aerojunk. There's a long way to go before this will be a proven all-weather, all-conditions rig, but it's certainly a very interesting line of approach.
  • 27 Sep 2013 13:57
    Reply # 1399644 on 1378058
    Paul,
    well done, it looks like you have  finally got it all cookin.  You must be so pleased to have sorted out the jib before the end of the season.  I guess you have many tweeks in mind to keep you busy over the winter.
    Johann showed perhaps too much enthusiam,  the AeroJunk may be the best option for some boats / sailors, but not all.   As with the split rig, it does have a great advantage in a conversion, in that the mast can be more or less in the BM location.
    Having sailed with you on her previous iteration, I did not feel that parasitic drag was a problem.  Also, whilst looking complicated, I could see that it was actually quite simple to put together.
    What the AeroJunk needs now is a really good testing, in stronger winds, and any long term issues.  Just keep us posted.
    Cheers Mark

  • 26 Sep 2013 20:55
    Reply # 1399234 on 1378058
    Johann, your enthusiasm is good to see but somewhat premature.

    Paul McKay's rig is very interesting. It's also (in it's current incarnation) too complicated (as was the softwing) and has far to much parasitic drag (that the softwing did not have).

    It's also too new; only one in existence and very, very untried. To come to the conclusions that you come to, based on the very limited testing (and time the rig has been around) is frankly absurd. Doubly so when by your own admission you have about zero junk rig experience.

    None of this distracts from all Paul's hard work, it just common sense.

  • 26 Sep 2013 18:01
    Reply # 1399103 on 1378058
    Anonymous member (Administrator)

    Wow, Johann,

    if that is correct, then we can just as well shut down JRA and save ourselves a lot of trouble. Could you please tell us about what sort of cambered junksails you have tried since you are able to draw such a firm conclusion? I don't buy reputation as good enough documentation.

     

    Arne

    Last modified: 26 Sep 2013 20:28 | Anonymous member (Administrator)
  • 26 Sep 2013 12:25
    Reply # 1398848 on 1378058

    My comment about the aero junk:

    Some years ago I bought a Westerly Centaur and it became immediately clear to me that the Bermudan rig on a boat of this size is a choir to me (Greetings from my aging joints). So I began looking for an alternative rig which is easier to handle. Soon I got aware of the junk rig. I got the opportunity to sail with two junk rig boats, one with hinged battens and one with a cambered sail. Although this rigs where easier to handle, they did not convince me entirely. Having heard of alternatives within the junk community I contacted Sleeve about his split rig. I got some useful information from him. Unfortunately I had no opportunity to sail a boat with a split rig up until today. I had the opportunity to test the other alternative, the aero junk rig. I visited Paul McKay and sailed with him in light winds. This experience was so convincing to me that I finally decided to convert my boat to the aero junk rig.

    The performance in light winds was good (The standard junk has a reputation for bad performance in light winds). Handling of the boat was nearly like driving a motor boat. That is what I understand under relaxed sailing. I asked Paul to show me reefing. This was done with the same ease. Surprisingly the speed went down insignificantly despite the dropping of two panels.

    The rig looks a little bit sophisticated at the first glance, but it can easily be build. The sails are flat like the simplest junk sail. No need for difficult sewing like for the cambered junk rig or the split rig. The battens are simple straight battens which get their profile by appropriate distance holders. After all, the rig looks good. Every imaginable sail form can be realized.

    Knowing about this rig, every conversion to a standard junk rig, cambered or not, is simply a big mistake. Even compared to the split rig, I see big advantages for the aero junk rig.

    Thank you Paul for this contribution to the sailing community.

    Johann

     

  • 25 Sep 2013 20:52
    Reply # 1398113 on 1378058
    I have to admit it - the sails seem to be taking up a good shape. Well done, Paul, it's taken a few iterations, as these new ideas tend to do, but you're getting there. Though I still don't like the look of the exposed battens, aesthetically.
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