About the Junk Rig

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  • 24 Apr 2020 11:57
    Reply # 8925559 on 8921369
    Anonymous member (Administrator)

    When I replaced Johanna’s bridle type lazy jacks (LJ) with the present ones (and which Ingeborg basically makes use of), one of the arguments was to reduce distortion of the sail camber. As the super-clear photo (2008) of Johanna shows, a couple of postings below, the bridle type LJ do cut a bit into the sail. That photo also shows that the mast lift do little harm, except at the lowest panel. The worst ‘camber killer’ on a plain cambered-panel sail is no doubt the mast, on port tack. Still as the photo below shows (also from yesterday’s outing), all the leech telltales are flying nicely. That is the proof that there is attached airflow over the leeside of the sail. To me that is a very important success factor.
    On that photo we are hard on the wind, but the leeward topping lift appears to distort only the lowest panel, and then only a bit.


    The Slieve type canvas sail catcher with tubes at the upper edge is on my to-do list.
    I see four reasons for fitting it:

    ·         I will save quite a bit time each time I make the sail ready before and after an outing. Today I must tie up the furled bundle after each sail, before ‘putting the lid’ on.

    ·         The canvas sail catcher will stow the reefed bundle better when under way, so I avoid any blanked view forward.

    ·         This sail catcher protects the furled bundle very well against sunshine.

    ·         A top lid will be much quicker to fit than today’s version.

    It should be very easy to retrofit my rig with these sail catchers. I only need to climb the mast to attach the needed sb. mast lift ...

    Cheers,
    Arne

     


  • 24 Apr 2020 00:35
    Reply # 8924855 on 8921369
    Anonymous member (Administrator)

    On the subject of lifts and lazyjacks interfering with the camber of the sail, I rather agree with Arne that it probably doesn’t matter much, in practice.

    When I made my rig I did worry about this, and I think I have been able to reduce that interference to some extent – for what it is worth. With a split junk rig together with Slieve’s sail catcher, lazyjacks can be left out of the rig as redundant. The lifts are in two pairs and attach to the top edges of the sail catcher, supporting the bundle by way of a batten along each top edge of the sail catcher.

    The forward lift pair can be placed up and down the mast, where it is in the slot and does not interfere with the sail (and is out of sight in the photo below). I would expect that the camber at the fore part of the sail is the more important to be protected. Anyway, with the SJR neither the jibs nor the mains need be interfered with by the fore lifts (which are in place of the so-called "mast lift".)


    The only remaining issue is the aft lift pair. (These replace what some people like to call the "topping lifts" but actually they are for a different purpose.) This pair can potentially interfere with the sail but mainly out near the leech where the camber is least – and can be placed as far aft as possible (consistent with them not being able to get on the wrong side of the yard when raising and lowering the sail) as seen in the photo above. 

    Another potential mitigating factor is possible with respect to the aft lift pair, and that is to spread the two support battens which support the sail catcher, by means of a hairpin joiner at the front, and some sort of equivalent at the aft end which does not foul the sheets. You can get the idea by looking at the hairpin on the front of Amiina’s sail catcher. I never got this figured out properly and decided it wasn’t worth the effort, but if pursued, spreading the sides of the sail catcher a little will give a little bit more stand-off to the aft lifts, so that almost none of this rigging should interfere much at all with the sail. As I said, I don’t think it matters enough to be worth the trouble, and, as a matter of fact, the sides of the sail catcher seem to spread themselves to some extent anyway, as soon as reefed panels and their battens fall into the catcher.

    I think Serendipity’s simple 2-pair lift arrangement, with sail catcher and no lazyjacks, is (for the SJR at least) about as simple an arrangement as you can get, and with minimum interference with the sail camber…. for what difference it makes – which is probably not much. The SJR and sail-catcher is a delightful arrangement in my view, but mainly for other reasons.

    Its wonderful to see Arne's photos of sailing right now, in a nice breeze. I'm envious!


    Last modified: 24 Apr 2020 01:17 | Anonymous member (Administrator)
  • 23 Apr 2020 18:32
    Reply # 8924247 on 8921369
    Anonymous member (Administrator)

    Ueli;
    unfortunately there is no way one can play with the topping lifts to prevent them from cutting into the bulging panels, except with the sail fully raised. With reefs in, both topping lifts are called for to collect the reefed-away sail bundle.

    Below is a fresh photo of my Ingeborg’s sail, taken this afternoon, on our very first outing (solo) in many months. There was a good breeze blowing, maybe 12-14kts, and both topping lifts can be seen working. The lee topping lift thus cuts a bit into the panels. That’s the way it is. BTW, if you enlarge the photo, you will notice that the two upper Hong Kong parrels are slack. When sailing close-hauled, they are taut, mostly, but don’t appear to be under hard strain.

    Arne



    Last modified: 20 Mar 2023 11:20 | Anonymous member (Administrator)
  • 23 Apr 2020 08:25
    Reply # 8923355 on 8921369

    arne, you're right. as i see on your picture, it's not a big problem. but in the visualisation it looks as the lifts would be adjusted every time.

    ueli

  • 22 Apr 2020 21:41
    Reply # 8922697 on 8921369
    I like it! Thanks to the one who build that!
  • 22 Apr 2020 21:15
    Reply # 8922589 on 8921369
    Anonymous member (Administrator)

    Ueli,
    I wouldn't worry to much about the (real life) topping lifts. With the sail fully hoisted, they ar too slack to do any harm to the camber, and when the sail is reefed, the wind is generally strong enough to inflate the sail quite well. The topping lifts only distort the camber a little bit. That has never caused any concern on my boats.

    As can be seen, Johanna, below, with one reef in the sail, keeps on sailing, quite happily.

    Arne


    (Photo: Peter Manning)

    Last modified: 20 Mar 2023 11:15 | Anonymous member (Administrator)
  • 22 Apr 2020 19:46
    Reply # 8922251 on 8921369

    …and i don't really like the free flying topping lifts on the lee side. (well, i would like them on a real rig – but unfortunately they don't fly like that – unless you adjust them on every tack.)

    …but it's good to have this visualization.

    ueli

    Last modified: 22 Apr 2020 19:48 | Anonymous member
  • 22 Apr 2020 17:05
    Reply # 8921682 on 8921369
    Anonymous member (Administrator)

    I agree. Still, I am not so sure I like a 6-part sheet with no antitwist in it. 

    Arne

  • 22 Apr 2020 15:04
    Message # 8921369
    Deleted user

     I really like the clear 3D illustration added to the About the Junk Rig section and the way it shows the lines on this particular sail, especially the parrells in color.

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