Split Junk, Cambered panel or hinged batten sail. Which to choose?

  • 08 Dec 2012 06:27
    Reply # 1154946 on 1154434

    Graham, I bet that some of the negative-stagger problems you got when changing to cambered panels stems from the forward-raking mast. With the mast raking forward, the mast top, where the halyard goes, will be well forward of the base.  Arne

    You may be right Arne, and perhaps also that I shortened the yard.  My battens are 4.6m but my yard is only 4m, which puts the sling point further forward and increases the sail's desire to swing forward when unrestrained by parrels.  In all other respects my sail is a standard HM sail with a transitional panel like yours.  I have tamed the beast now, using your throat hauling parrel set up to control the stagger.   I like the enhanced performance, both the windward ability, the improved tacking and the speed with which the boat accelerates out of a tack, very useful when sailing in close quarters.  I still have my flat sail tucked away but I will keep sailing with the cambered sail for a year or so and see if I can get it to a stage where I can reef at night without getting into a tangle. (That's my benchmark for ocean cruising!)
  • 08 Dec 2012 02:00
    Reply # 1154832 on 746824
    Here, just as they came from Alan, are some more notes on the new sails:

    NEW ARNE TYPE SAILS FOR ZEBEDEE

    It’s amazing how much time we spend tacking. We wanted better performance and Arne’s method seemed the easiest. We went for 10% camber in the lower panels, reducing to 4% then 1% in the triangular panels.

    We obtained some black Odyssey III cloth 64 inches wide, V69 thread, 3/8 inch polyester bolt rope and 3mm polypropylene line for the inner bolt rope. We used our hand cranked Singer (cost GBP8), no walking foot, no zigzag and no reverse. Pauline’s uncle Paul Moretti put us up and let us use his living room and garage. We were fed like kings!

    We extended the battens 8 inches back to the original 150 inches. For marking we used tailor’s chalk and silver felt tip pens.

    We followed Arne’s method to the letter (Amateur Method B), including cutting 10 inches off the leech of the booms. We made the sails 152 inches wide to ensure sufficient slack to allow the camber to form. Slieve very kindly provided the camber figures, max camber at 35% chord for the bottom panels to about 45% for the triangles.

    Stapling was particularly helpful when joining panels and for fitting the pockets. Use of a staple remover (very cheap) was very effective. We marked every sewing line to ensure accurate construction.

    It took us 5 days to build both sails, including lots of unpicking of the triangles. I still don’t know how I got those so wrong!

    We fitted throat hauling parrels and Hong Kong parrels. There were no major creases and the pressure on the battens seems fine.

    We sailed in Trinidad for 3 days, wind varying from calm to F5 and gusty. There is a tremendous increase in speed when hard on the wind. Unfortunately the wind has been too flukey to measure the tacking angle. It is certainly better than before.

    We ll let you know as we get more data, sailing in different conditions.

  • 08 Dec 2012 01:31
    Reply # 1154827 on 746824
    Deleted user
    Just compared the theoretical camber between Zebedee's and ours using the numbers Alan supplied. Using Arne's new formula  (R=0.55 x camber),  Zebedee's would be 9.1% versus ours of 8.7%. Little too baggy for comfort.
    Yes David, I have slight concave in the aft curves, tabling only on the leech (no bolt rope planned), and may add webbing to the luff though (on top of tabling).
  • 07 Dec 2012 20:00
    Reply # 1154648 on 1154632
    Arne Kverneland wrote:What a contrast to how we do it in Stavanger: Construct the sail, rig the sail and go sailing. Period.
    Sorry, Arne, but this isn't the whole story. You, too, for example, had to learn how a throat parrel, correctly rigged, helps to take the load off the HK parrels and set the sail better. There isn't any essential difference between sails made in the way that you do, and sails made in a different way, to a different pattern. We all have to construct the sail, rig the sail and go sailing to see what manner of rigging will give the best set to the sail. You've been through that exercise, travelled up the learning curve, until now, repeatably, you can  construct the sail, rig the sail and go sailing.

  • 07 Dec 2012 19:46
    Reply # 1154633 on 1154619
    Kurt Jon Ulmer wrote:
     Because it's becoming increasingly obvious, I think, that something is at least a little bit given up to gain something else.

    Cheers,
    Kurt
    Again, exactly so. Such expressions as "There's no such thing as a free lunch" come to mind. But you might also say "The more you put in, the more you can get out". More into sail design and construction, to get more windward performance. If you want it, or if you need it.
  • 07 Dec 2012 19:41
    Reply # 1154632 on 1154596
    Anonymous member (Administrator)
    Annie Hill wrote:Hi Arne

    Well, there isn't one, really.  And I'm still tweaking.  Essentially, standard YHP, a luff hauling parrel and one standing luff parrel.  I'll post a photo on the photogallery which shows the set up of the LHP.  Still working on getting the boom set just as I want it.  Of course, I haven't had a chance to sail the boat for 3 months (!) what with caring for my friend and then hauling out.


    Annie,

    I am sure you get it right, but I think it will be generally easier to handle the batten stagger and diagonal creases with a vertical or a bit aft-raking mast than with the mast raking forward. I can't help wondering what is going on when I read about boats needing weeks of  tweaking and fuss to get the sails right. What a contrast to how we do it in Stavanger: Construct the sail, rig the sail and go sailing. Period.

    Cheers, Arne

    Last modified: 07 Dec 2012 19:58 | Anonymous member (Administrator)
  • 07 Dec 2012 19:32
    Reply # 1154619 on 746824
    Graham,

    It's very interesting to read this discussion, and imagine somebody in the UK tying their whatever parrel a different way after somebody in Australia learned it from somebody in Norway who had a guy in the Caribbean try it out... or something like that.

    Not many people have sailed the same boat with two different cuts of junk sails. You, Annie, Alan now, Pete, David, David and surely a few more. Your reports have been clear as a bell, and you've related your impressions to current designs and practice, and the problems that other people are also working on. 

    It has to help make sails more workable. I sure hope people who resort to recutting their sails, one way or the other, get the results they want. Because it's becoming increasingly obvious, I think, that something is at least a little bit given up to gain something else.

    Cheers,
    Kurt
    Last modified: 07 Dec 2012 19:34 | Anonymous member
  • 07 Dec 2012 19:18
    Reply # 1154609 on 1154603
    David Thatcher wrote:I suspect that the way the battens stack is more a function of sail design rather than mast rake.
    Exactly so. Earlier on, I tabulated my calculations regarding the correct diagonal measurement to use for any given camber, and this applies whether the sail has parallelogram panels or fanned panels. Forward rake in the mast will exacerbate the problem of negative stagger on a badly designed sail, but it will have no effect on a correctly designed sail.
  • 07 Dec 2012 19:11
    Reply # 1154605 on 1154261
    Gary King wrote:Thanks for all this. Having cut all 7 panels for our main, it's not too late to draw in a thinner rounding as they arent sewn together yet. You've all convinced me 8.5% camber might be too much for our ocean crossing to Indo. Think I'll chop it down to 4 or 5%.

    As for Zebedee (great articles btw Alan, if you're lurking:)), I reckon he may have complaints if he is keeping the same battens & yards. But may have helped those times battling adverse winds and currents.
    Yes, 4 or 5% would be good for an ocean crossing. Do bear in mind the point about 'reflexing' the curve so that it is convex in the forward part of the panel, then is slightly concave in the after part. I made the curve convex in the forward half, with a straight line to the aft end, and this does put the fullness a little too far aft, in the finished sail. I'm still studying the photos of Zebedee, but it seems to me that the fullness is a little too far aft.
  • 07 Dec 2012 19:07
    Reply # 1154603 on 746824
    Deleted user

    I suspect that the way the battens stack is more a function of sail design rather than mast rake. On the original, every mistake made, version of Footprints old sail the battens were all over the place when the sail was lowered. When I rebuilt the sale to PJR guidelines the battens stacked exactly as they should. With the new fan shaped sail the battens stacked properly with the mast vertical, and they also stack properly with the mast now raked forward. I have only 3 degrees of rake against the 6 percent on Fantail. The forward raking of my mast was required to get the centre of effort of the sail where it should be for the boat, and also as David Tyler has observed these fan shaped sails seem to sit better on a forward raking mast. Fortunatly my sail seems to be working well with a fairly simple arrangement of the control lines and with no manipulation of battens required to get them to stack as they should. The only extra line over the old sail is the luff hauling parrel which I did not need on the old sail. Maybe because the sail was so heavy (16oz Duradon) gravity did that job for me. So on Footprints there is main halyard, yard hauling parrel which is not required for full sail as the yard sits hard against the mast anyway, and the luff hauling parrel which can require a bit effort due to the size of Footprints sail, but that is also about technique. Both Tystie and Footprints have 2 additional control lines connected to the boom which adjust the canting of the sail across the mast but there is no load on these lines. We do adjust our topping lifts, they are at a fixed length.

    As per Annies comment above the boom sits at funny angles on the new sail and doesn't seem to do much other than stretch out the bottom of the sail. I still have the old heavy timber boom from the old sail. I suspect I could get away with some much lighter alloy tube for a boom, but because it sits in a sleeve at the bottom of the sail I never really see so I tend to forget about it.

    I do have to say that David Tylers idea of putting all the sail spars; battens, yard and boom in sleeves is a great idea. Although it is a little more work when making the sail it is a very simple and clean arrangement when completed and especially when combined with the sewn in foam mast cushioning on the sleeves. 

    Last modified: 07 Dec 2012 19:16 | Deleted user
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