Ingeborg and Jester - comparisions between sail area and cambered or flat panels.

  • 08 Aug 2016 19:32
    Reply # 4178627 on 4175442
    Anonymous member (Administrator)

    Robert,

    I think I see your point. However, my first priority is to have a good twist control on that big top section of the sail. As long as I can sheet the sail in for fully close-hauled  sailing, I can live with slack sheetlets when the furled bundle is brought to the centerline. I have my ways of controlling that. So far I have not found a useful set of sheetlets which  controls the twist of my sails better than the Johanna-sheeting, unless one fits a second, upper sheet. However, your setup may well be perfect for your split JR.

    Arne

    Last modified: 08 Aug 2016 19:37 | Anonymous member (Administrator)
  • 08 Aug 2016 18:45
    Reply # 4178515 on 4177215
    Deleted user
    Arne Kverneland wrote:

    Now, after test-sailing Ingeborg, I see that she could well have taken a sail with a shorter boom and AR= 2.00 instead of the one I built, with AR=1.90. This sail would improve sheeting clearance and also make the helm lighter on a reach.

    Hi Arne--With respect to your sheeting clearance. My sail is also 7-panel and 6-point sheeting. I initially copyed your Johanna sheeting and used your anti-twist config to the top 3 battens (derivative of PJR, fig 4.24). The Dmin was a bit too long by mere 10's of centimeters. I re-rigged the top 3 battens following PJR, fig 4.28 (fig 4.17 is the same) and it worked to reduce the Dmin enough to remove the slack when the sail bundle is lowered. Might work for you too?

    rself


    Last modified: 08 Aug 2016 18:46 | Deleted user
  • 08 Aug 2016 12:48
    Reply # 4178057 on 4177931
    Iain Grigor wrote:

    Why does the ability to cant the sloop sail over the mast when off-wind require a "much longer boom" as David Thatcher says below?  Is there anywhere on this site which gives details about how to rig the sail so that it will cant? 

    Can anyone supply instructions as to how to rig the sail for this?

    Iain, written out in full, that would be: "much longer boom parrel and batten parrels".

    Have a look at this photo of Tystie. And this one, too. There are single and becket blocks at the mid-point and at the forward end of the boom. A line runs from the becket of one block, around the mast, around the sheave of that block, down to a deck block at the foot of the mast, back to a clutch near the companionway, back through another clutch, through another deck block, around the sheave of the second block, around the mast, and finally to the becket of the second block.

  • 08 Aug 2016 09:48
    Reply # 4177931 on 4175442

    Why does the ability to cant the sloop sail over the mast when off-wind

    require a "much longer boom" as David Thatcher says below?  Is ther anywhere on this site which gives details about how to rig the sail so that it will cant? 


    There is nothing, or next to nothing, in PJR about this apart from the obvious need for a running tack parrel ....


    I suppose the really obvious first thing to do when the helm gets heavy offwind is to reduce sail and ease the sheet.  On my boat, with Hydrovane self-steering, I can also cant the auxiliary rudder when I am hand steering.  Or, of course, cant the main rudder when the Hydrovane is steering. 


    But I can't help suspecting that the ability to cant the sail forward would be a good thing too .....


    Can anyone supply instructions as to how to rig the sail for this?

  • 07 Aug 2016 23:00
    Reply # 4177438 on 4177384
    Arne Kverneland wrote:

    Zane,

    I can assure you that the total length of Ingeborg's mast is 6m + 3.7m = 9.7m. I can only guess on the height of the mast above the waterline, but it must be somewhere between 9.5 and 9.7m That is the benefit of having a low-AR Johanna-style sail: You get a lot of sail area on a quite short mast.

    If you open the diagram on my posting a little down from here, you will notice that the diagram has a meter scale alone the right edge. See for yourself.

    Arne


    Hi Arne - of course! How dopey of me. I was looking at the 11m measurement which is to the top of the top sail panel, not to the top of the mast.

    This means the mast off my previous boat is only 4cm less than your Folkboat, and she be easily adaptable to my Contessa.

    Cheers,

    Zane. 

    Last modified: 08 Aug 2016 01:52 | Anonymous member
  • 07 Aug 2016 22:21
    Reply # 4177407 on 4177325
    Anonymous member (Administrator)
    David Thatcher wrote:

    'Footprints' with her low aspect sloop rig can be very heavy on the helm when going downwind, although less so with her new rudder. At David Tyler's suggestion when he designed my new rig we have set things up so the boom and lower portion of the sail can be canted across the mast so that almost half the boom is across the mast. This has the effect of balancing the sail and allows me to carry a lot of sail downwind with almost no, or even neutral helm. Canting the sail across the mast like this requires much longer boom and batten parrels and is a little more work, but not that much compared to the gains of a light helm and the ability to carry a lot of downwind sail and hence a lot more speed.



    David, I can see your point.

    If I had long distance offshore voyages in mind, I may well have modified the batten parrels and control lines for shifting the sail back and forth. However, for my short coastal hopping I don't feel the need for it  -  and it takes a lot to overwhelm the rudder of a Folkboat, I can assure you.

    If I were to press old Otto, my windvane into use again (an old Belcher OGT Mk II), I guess I would construct an aux rudder for it and fit it to the port of the rudder. In use I would set the main rudder to trim out any weather helm, to ease the windvane's  and aux. rudder's job with holding the course.

    Arne

    Last modified: 07 Aug 2016 22:22 | Anonymous member (Administrator)
  • 07 Aug 2016 22:08
    Reply # 4177384 on 4175442
    Anonymous member (Administrator)

    Zane,

    I can assure you that the total length of Ingeborg's mast is 6m + 3.7m = 9.7m. I can only guess on the height of the mast above the waterline, but it must be somewhere between 9.5 and 9.7m That is the benefit of having a low-AR Johanna-style sail: You get a lot of sail area on a quite short mast.

    If you open the diagram on my posting a little down from here, you will notice that the diagram has a meter scale alone the right edge. See for yourself.

    Arne

  • 07 Aug 2016 21:31
    Reply # 4177352 on 4176052
    Arne Kverneland wrote:

    This topic raises a number of sub topics; camber, rig size, radical versus conservative, fit for offshore or not, etc.

    Rig size first.
    I have PJR and a calculator by my side, right now. I find that Jester’s mast height is about 10.3m above the water line. Ingeborg’s mast is only about 9.6m tall (above wl.). Still, one seems to regard Ingeborg’s rig to be the ‘huge’ one.

     

    I'm confused. with your quoted measurements above Arne.

    Isn't your mast 9.7 tall from the partners on deck level, and actually 11m tall from the waterline?

    This is all of interest to me as I have a Contessa 26 (Canadian version) down here in NZ, and am going to (at this stage) to transpose the mast and sail (285 sq ft) from my previous JR boat which mast is 8m above partners (LAP) and 1.3m bury, making 9.3m overall.

    Rather than lengthen the mast I am going to see if I can get away with adding another panel of about 60 sq ft making about 345 sq ft over-all. And will lengthen the bury in some fashion too of course.

    Early days for me in this conversion, but this is the current line of thought with me and my JR designer friend downunder.

    Last modified: 07 Aug 2016 21:37 | Anonymous member
  • 07 Aug 2016 20:45
    Reply # 4177325 on 4177215


    PS: You are of course right, Graham. It only takes a reef or two to regain a light helm downwind. I found that even on Johanna’s low and wide sail (AR=1.87), the needed rudder angle would be low as long as I didn’t set more sail downwind than she could carry close-hauled. However, I like to speed on, if I can...

    'Footprints' with her low aspect sloop rig can be very heavy on the helm when going downwind, although less so with her new rudder. At David Tyler's suggestion when he designed my new rig we have set things up so the boom and lower portion of the sail can be canted across the mast so that almost half the boom is across the mast. This has the effect of balancing the sail and allows me to carry a lot of sail downwind with almost no, or even neutral helm. Canting the sail across the mast like this requires much longer boom and batten parrels and is a little more work, but not that much compared to the gains of a light helm and the ability to carry a lot of downwind sail and hence a lot more speed.


  • 07 Aug 2016 17:27
    Reply # 4177215 on 4175442
    Anonymous member (Administrator)

    In all the cases where I have fitted (sloop) junkrigs, the aspect ratio (AR) of my rigs has been dictated by the deck/interior layout of the vessels.  If I could start from scratch, I would in most cases choose an AR of between 2.00 and 2.10. These medium hi-AR sails are good both upwind and downwind. However, the layout of most of my boats, Malena, Johanna, Frøken Sørensen and Ingeborg have forced the masts forward, which again has forced me to draw rather low-AR sails. These are a little less easy to trim to set well, and they tend to give harder steering downwind. On Broremann, on the other hand, the mast was forced to sit aft, to avoid a buoyancy tank, so that resulted in a tall sail with AR=2.15. That worked well.

    Now, after test-sailing Ingeborg, I see that she could well have taken a sail with a shorter boom and AR= 2.00 instead of the one I built, with AR=1.90. This sail would improve sheeting clearance and also make the helm lighter on a reach.

    Here, in dashed lines you can see how such a sail would compare with Ingeborg’s (as built) sail.

    Cheers, Arne

    PS: You are of course right, Graham. It only takes a reef or two to regain a light helm downwind. I found that even on Johanna’s low and wide sail (AR=1.87), the needed rudder angle would be low as long as I didn’t set more sail downwind than she could carry close-hauled. However, I like to speed on, if I can...

    Last modified: 07 Aug 2016 17:29 | Anonymous member (Administrator)
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