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Ingeborg, Arne's Marieholm IF

  • 01 Jul 2016 09:20
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    Reply # 4110219 on 3032430
    Anonymous member

    Arne wrote, " I would think that the split junk rig, SJR, is more forgiving on a reach in this respect than the low-balance sails that I use to make, since there is about 30% balance in the sail of a SJR. In other words, if you get the balance right for close-hauled sailing, it will stay quite right on a reach as well. I am sure Slieve can verify that.."

    Yes I can. I feel the high balance of the split rig is a major asset and makes for an easily handled boat. It's great for lazy sailors like me.

    By the way, the Round the Island race is tomorrow and Edward and Steve are racing Amiina with its new split rig. There are a number of significant changes in this rig, so it will be interesting to see how they get on. They can be tracked during the race by following the link on the J P Morgan Round the Island web site. They are in the ISCRS Division 8D, starting at 10:10. It looks like a windy race for a small light boat, and could be very tiring. I wish them good luck.

    Cheers, Slieve.

    Last modified: 01 Jul 2016 20:03 | Anonymous member
  • 30 Jun 2016 22:09
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    Reply # 4109664 on 3032430
    Anonymous member (Administrator)

    Scott.

    One of the things I have stressed many times is the need for big, efficient and preferably balanced rudders. This is particularly important if the JR is of the sloop type and with a wide chord sail. Far from all off-the-shelf yachts have rudders that will fill this requirement.

    The problem is not to make a boat balance reasonably well to windward. The problem is to deal with the rise in weather helm as one falls off onto a reach or run (reach is worst). I have therefore started to compare the chord of the sails with the waterline length of the boat.

    On Johanna that ratio is 0.84. Thanks to Johanna’s initial neutral helm and a good, balanced rudder, she coped well, although I would not recommend her rig-boat combination as a round-the-world setup.

    On Frøken Sørensen the same chord/wll= 0.57. In addition, FS has an enormous, streamlined and fairly well-balanced rudder, all the way aft (sail plan below), so that vessel is ideal for a sloop JR.

    On Ingeborg, the chord/wll=0.80. I guess that is close to maximum of what I would have on a go-anywhere boat. Ingeborg has a big rudder, quite well aft, but the rudder area is unbalanced. The Folkboats didn’t come with those long tillers for no reason. Paul on his La Chica got a lesson about the heavy steering with unbalanced rudders, and solved it brilliantly by replacing the original one with a much better, balanced NACA foil.

    I would think that the split junk rig, SJR, is more forgiving on a reach in this respect than the low-balance sails that I use to make, since there is about 30% balance in the sail of a SJR. In other words, if you get the balance right for close-hauled sailing, it will stay quite right on a reach as well. I am sure Slieve can verify that.

    The fact that I initially missed a bit on Ingeborg’s balance, was partly because I got a bit sloppy, and partly because the good, balanced rudders I have had on the three last boats, have spoilt me. Luckily, it seems to be easier to set Ingeborg’s sail in the forward position, than in the original, so I was lucky there.

    Frankly, I think it is easier to get the balance right if the boat has a fin keel and spade rudder, than with the rudder working in the eddies, right behind a long keel.

    Arne

     

    Last modified: 12 Jan 2019 18:37 | Anonymous member (Administrator)
  • 30 Jun 2016 14:48
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    Reply # 4108991 on 3032430
    Deleted user

    I'm not sure if that answer makes me more concerned or less.  That wwl% change is about 9 inches on my boat, which doesn't seem like much.  On the one hand, it's good to know that small changes like that have a significant effect on the balance.  On the other hand, it means that if I better not miss my initial design analysis by much.

    Annie's comment about the ease of changing the balance of the rig has me wondering, though.  It seems that a Bermudian rig actually has us beat there because it is relatively easy to change headsails.  With a junk, if you've got poor balance and it's outside of what the limited fore/aft shift can be, you've got to redesign and refabricate the whole sail. 
  • 23 Jun 2016 18:40
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    Reply # 4094698 on 4094580
    Anonymous member (Administrator)
    Scott Dufour wrote:

    Arne,

    The ability to make those balance changes on your sail has me thinking about whether using a split-rig gives that up.  Are the balance adjustments you've been doing of a magnitude that they would have put a the jiblet/main split in the wrong place on the mast?


    I moved the sail forward 150, or maybe up to 170mm which is 2.5-2.8% of the wll. I cannot tell what that would be on your boat, or if it would move the slot into an awkward position. It takes a bit bad luck to miss as much as I did here.
  • 23 Jun 2016 17:37
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    Reply # 4094580 on 3032430
    Deleted user

    Arne,

    The ability to make those balance changes on your sail has me thinking about whether using a split-rig gives that up.  Are the balance adjustments you've been doing of a magnitude that they would have put a the jiblet/main split in the wrong place on the mast?
  • 23 Jun 2016 16:38
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    Reply # 4094513 on 3032430
    Anonymous member (Administrator)

    Balance problem solved

    Today we had a third sail in Ingeborg. This time I made ready a longer tack parrel which I replaced the first one with, after hoisting sail. Then, this time I set up the yard hauling parrel, YHP, before the throat hauling parrel, THP. As you can see on the attached photos, this has shifted the sail about 150mm forward, compared to on the test-sail, two days ago (on Johanna I developed the habit of hauling in on the THP first, to bring the sail aft, and remove lee helm).

    This had the desired effect. In light winds Ingeborg is now next to neutral on the helm, and it remains light as the wind picks up. The resulting position of the CE is still 150mm (2.5% of wll) aft of the Bermuda rig’s CE, which is as it should be. A bonus is that THP- and YHP forces seem lighter than with the sail hauled aft. At the end of the little trip, the sail was lowered and came down as it should. Win-win!

    I also tested the home-made tiller brake/lock, similar to the one used on Frøken Sørensen. This is the last and final development step of it, starting on Broremann in 2009 (Check “Broremann” on Youtube). Ingeborg went straight as an arrow across the fjord, with it on, see photo below.

    That’s more like it. I am still doing fine-adjustments to the sheetlets, and I also have to find optimal cleat positions for the sheet, the YHP and the THP. But it is about to become fun!

    Arne

    The album 4 was lost by Wild Apricot, so I let you have this from Photo Album 5, taken in 2017


     

    Last modified: 07 Feb 2024 21:50 | Anonymous member (Administrator)
  • 22 Jun 2016 23:32
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    Reply # 4092219 on 3032430
    Anonymous member (Administrator)

    David,
    there is a lot of "optics" going on when watching sails, in particular when watching cambered panel junks. The photo below was taken a short while later, but with the sun coming at a different angle, the sail suddenly appears to be flatter.

    Annie,
    it has much to do what tiller forces I am used to (but not only that).  I hope to get a chance to test-sail Ingeborg again, tomorrow. Today I have made a tiller brake to keep the boat steady when hoisting sail ( or else she will use up the bay while I am hoisting sail). The tiller brake, which is an improved version of the one used on Broremann and Frøken Sørensen (FS), will hopefully let me sail across the fjord, hands off, as on FS.

    Arne

     

     

    Last modified: 22 Jun 2016 23:34 | Anonymous member (Administrator)
  • 22 Jun 2016 22:13
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    Reply # 4092141 on 4090879
    Anonymous member
    Arne Kverneland wrote:Still, close-hauled we went just below 5.0kts and when beam-reaching, we touched 6.2, so it is not bad.

    Arne

    A masterpiece of understatement, Arne! Most people would be more than happy with those speeds!

    I dare say even a Folkboat will feel quite shippy after your little Frøken.  I hope you soon get used to the difference.  It will be interesting to hear if you get rid of the weather helm.  It's one of the many advantages of junk rig, that you can make significant adjustments to the CE of the rig by just tweaking a few lines!

    Last modified: 22 Jun 2016 22:22 | Anonymous member
  • 22 Jun 2016 07:38
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    Reply # 4090879 on 3032430
    Anonymous member (Administrator)

    It could be, David,

    but I doubt it. The sail has been designed and cut the same way as the last three sails I have made, and the shadow pattern doesn’t look different from them.

    I therefore suspect other reasons.

    • ·         The CE of this rig is 300mm aft of the CE of the Bm rig when the sail is set with 10% balance. I can easily increase the balance to 13 – 15% by moving the sail 200 – 250mm forward.

    • ·         I am a spoilt kid. After having had only fin-keel boats with balanced spade rudders for the last 35 years, I am used to fingertip control, even when the rudder is set at some angle. The big unbalanced rudder of a folkboat has higher tiller forces, even at a low rudder angle.  I have sailed a lot in folkboats, so know them well.

    • ·         I should not worry about speed until I have put on new antifouling. She is quite dirty. Still, close-hauled we went just below 5.0kts and when beam-reaching, we touched 6.2, so it is not bad.

    Arne

     
  • 22 Jun 2016 06:46
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    Reply # 4090850 on 3032430
    Anonymous member

    Looking at this photo, Arne, the shadows seem to be showing that the depth of camber in the top three panels is rather far aft. Is this an optical illusion? If not, I reckon this to be a cause of weather helm and dull performance. I know, I know, it would be a nuisance to have to take the sail off and resew those panels a bit flatter, but maybe it would better to do this than move the sail forward?