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

  • 12 Nov 2011 20:19
    Quote
    Reply # 748530 on 748495
    Deleted user
    David Tyler wrote:I can't sew a big sail without at least one, preferably two, helpers to move the bulk of the sail along the sewing table whilst I move just the part of the sail adjacent to the machine. Most sailmakers have a large slippery sewing table, with the machine set level with its surface. I use rollers under the flaked or rolled sail, in front of and behind the machine.
    Your plan to use a mobile sewing machine would have the advantage of needing a smaller space to sew in. Moving the sail along needs a lot of space in front of and behind the machine - just like passing wood through a sawbench. But I rather think the machine will need to be on some kind of rails, to keep it running straight?
    For 80>90% of the sail work I'll be alone. So I had to figure out how to not move the whole mess as it got larger and heavier.

    Picture a table 24'x6', (I haven't taken the exact measurements yet, but there's at least that much room for a table that size upstairs here.) In front of and as part of this table, there will be a shelf with rails for a sewing machine trolley, with the machine table at the same elevation as the tabletop. I built what amounted to a 40' railroad for my circular saw to cut the birdsmouths in the mast staves. That worked like a charm. (My staves are tapered in both directions; cutting the tapered birdsmouths would have been problematical without propping and clamping the staves at just right elevation.
  • 12 Nov 2011 19:36
    Quote
    Reply # 748519 on 748439
    Anonymous member
    Jonathan Snodgrass wrote:Could I please ask David:  After years with junk rigged boats your latest modification of Tystie was to a wing sail yawl.  However, it is not something that I have seen you recommend to anyone else.  In the case of Rodney, you perhaps haven't considered it as an option because he specifically asked for advice about junk rig sails.  However, he did include ocean robustness as one of his factors for consideration.  Would you care to comment?  jds
    I do think that my wingsail ketch rig gives better performance, and more driving force for a heavy boat,  than I could have got with a more conventional junk rig in ketch format - the only two masted option open to me. I don't think that the performance is very much better than the big single sail, fanned and cambered, that I was using before. The chief reason for changing was that I didn't feel the big single sail was entirely suitable for ocean cruising, though it was enjoyable to use for coastal cruising.
    Having said that, it is difficult to put a two-masted rig on to a boat of less than 30ft, and starting from scratch with a boat of 28ft, I would undoubtedly build a single sail similar to Fantail's.

      I hesitate to recommend the wingsail to others for several reasons:

    1. It requires rather more engineering skill than does junk rig, to make up the wishbone battens. I would like to be able to assure myself by direct contact that anyone taking on the job has a suitable workshop and sufficient levels of skill. I used Paul Thompson's workshop to make my latest set of battens, and I had the opportunity to see Paul at work; I know that he can do the job, and can complete the wingsail rig for La Chica.

    2. What I call the "80:20 rule" applies: it takes 20 units of effort to get 80% of the available performance; it takes another 80 units of effort to get the remaining 20% of available performance. Or call it cost/benefit analysis if you like. Either way, I feel that most people will get the most bangs for their buck by making one of the single-skinned junk rig variants. Leave the wingsails to we techies who just have to keep on designing and building things, because that's what keeps us amused and out of more serious mischief.

    3. I'm still struggling with ensuring the longevity of some of the batten components. I can't yet give out a recipe for a wingsail such that I can guarantee long term reliability.
     I broke several components during the Tasman Sea crossing (they were some of the original plastic parts that had become UV-degraded), and any such breakages are harder to deal with, being inside the sail.

    4. The sail is simple to make, but is 1 1/2 or 2 times the area of a single-skinned sail. More work, more weight, more expense.

    I'm still happy to talk to anyone who wants to build a wingsail - but they've got to want to build a wingsail, for the engineering challenge of it. There are other, simpler, less expensive ways to get a good rig.
  • 12 Nov 2011 18:42
    Quote
    Reply # 748495 on 748304
    Anonymous member
    Alan "Maddog!" MacBride wrote: Seems to me the  shelf/lens method lends itself to batten pockets (if using enclosed battens) or batten area reinforcement (for external, lashed through battens) for a sailmaker of limited experience, such as moi. Imo, once the tricky bits are together, it should be simpler to sew in the straight panels in between.
    I believe that's what Chris Scanes does, so you're in good company. However, I find that the batten pockets and end patches overlap the seams between lens and panel. I prefer to start from the bottom panel, add a lens, add the next panel, and then complete the batten pocket; then add a lens, add a panel, add a batten pocket, etc.
    I have a fairly large space to devote to building Alba's sail, but the prospect of shoving all that cloth around has me somewhat terrified. :-) So my plan is to move the sewing machine on rollers, a trolley, with the fabric remaining stationary. I hope it works as well as my similar system for cutting the mast staves.
    I can't sew a big sail without at least one, preferably two, helpers to move the bulk of the sail along the sewing table whilst I move just the part of the sail adjacent to the machine. Most sailmakers have a large slippery sewing table, with the machine set level with its surface. I use rollers under the flaked or rolled sail, in front of and behind the machine.
    Your plan to use a mobile sewing machine would have the advantage of needing a smaller space to sew in. Moving the sail along needs a lot of space in front of and behind the machine - just like passing wood through a sawbench. But I rather think the machine will need to be on some kind of rails, to keep it running straight?
  • 12 Nov 2011 16:41
    Quote
    Reply # 748439 on 746824
    Anonymous member
    Could I please ask David:  After years with junk rigged boats your latest modification of Tystie was to a wing sail yawl.  However, it is not something that I have seen you recommend to anyone else.  In the case of Rodney, you perhaps haven't considered it as an option because he specifically asked for advice about junk rig sails.  However, he did include ocean robustness as one of his factors for consideration.  Would you care to comment?  jds
  • 12 Nov 2011 12:05
    Quote
    Reply # 748304 on 748132
    Deleted user
    Annie Hill wrote:We discussed the phrase 'shelf foot' last night.  It's a bit confusing to non sailmakers and is used to differentiate the method David (and others) use from Arne's 'barrel' method.  We concluded that 'barrel vs lens' might be clearer and later in my snug bunk it occurred to me that 'teardrop' might also be appropriate.  With Arne's 'barrel' method you put curved fabric along a straight batten.  With the 'lens' or 'teardrop' method, you sew a piece of fabric that shape between two panels and attach the batten along its (straight) centreline.

    Probably everyone else knows this anyway, but I thought someone might appreciate the clarification.

    Seems to me the  shelf/lens method lends itself to batten pockets (if using enclosed battens) or batten area reinforcement (for external, lashed through battens) for a sailmaker of limited experience, such as moi. Imo, once the tricky bits are together, it should be simpler to sew in the straight panels in between.

    I have a fairly large space to devote to building Alba's sail, but the prospect of shoving all that cloth around has me somewhat terrified. :-) So my plan is to move the sewing machine on rollers, a trolley, with the fabric remaining stationary. I hope it works as well as my similar system for cutting the mast staves.
  • 12 Nov 2011 03:50
    Quote
    Reply # 748132 on 746824
    Anonymous member
    We discussed the phrase 'shelf foot' last night.  It's a bit confusing to non sailmakers and is used to differentiate the method David (and others) use from Arne's 'barrel' method.  We concluded that 'barrel vs lens' might be clearer and later in my snug bunk it occurred to me that 'teardrop' might also be appropriate.  With Arne's 'barrel' method you put curved fabric along a straight batten.  With the 'lens' or 'teardrop' method, you sew a piece of fabric that shape between two panels and attach the batten along its (straight) centreline.

    Probably everyone else knows this anyway, but I thought someone might appreciate the clarification.
  • 12 Nov 2011 02:32
    Quote
    Reply # 748054 on 748029
    Anonymous member
    Gary King wrote:
    David, 
    The sails you made for Badger have 6% camber, doesn't seem like a lot for light to moderate breezes. (I roughly measured the main on our bermudan sloop to have roughly 10% camber). Is there any problem making them at 8%?
    Also, Arne uses a chain hanging on a wall to figure out camber. How do you do it for your shelf foot design?

    Gary,
    No, 6% isn't a lot. The camber can be set at anything between 0% and 10%, but the more the camber, the bigger the problems in  getting it to set well and look nice, and the worse it looks when there is no wind. If that bothers you. I'm happy to stick at 6% for a serious cruising boat. Arne uses 10% for an inshore boat, but I feel nervous about having a lot of loose cloth around; it's getting to be a bit too un-chinese for my peace of mind.
    The shelf foot is simply drawn to the shape that you think the camber ought to be, because it should set more or less perpendicular to the panel itself. I draw a straight line for the after half of the edge of the shelf, tangent to a circular arc forming the forward half of the edge. A straight line from luff to leech, between each end of the edge, is where the batten will lie, and you can mirror the edge of the shelf about this straight line to obtain a lens-shaped piece of cloth. This is stitched between two panels, and the batten arrangements added.

  • 12 Nov 2011 01:51
    Quote
    Reply # 748029 on 746824
    Deleted user
    David, 
    The sails you made for Badger have 6% camber, doesn't seem like a lot for light to moderate breezes. (I roughly measured the main on our bermudan sloop to have roughly 10% camber). Is there any problem making them at 8%?
    Also, Arne uses a chain hanging on a wall to figure out camber. How do you do it for your shelf foot design?
  • 12 Nov 2011 01:42
    Quote
    Reply # 748025 on 747847
    Anonymous member
    Barry & Meps / Stellrecht & Schulte wrote:Rodney,

    Flutterby is a Freedom 33 (in the US aka 35 in the UK/Europe), and I expect to have the sails I designed for her up in a few weeks, and be able to report more about them.

    I sewed cambered sails, but did make my main sail more like Slieve's split rig. I believe there are reasons to use one on my forward-most sail:
    1. Slieve believes that having a "jib" like sail which has a clean leading edge out fully in front of the mast has aerodynamic benefits.

    Look for much better answers as to how my ideas worked out after some test sailing.

    Barry
    Barry,
    Sorry, I'd forgotten that you had made your mainsail as a split junk. I must amend my remarks to say that the split junk might well be worth trying on the mainsail of a ketch, but will probably not repay the extra effort on the foresail of a schooner, and will certainly not be worthwhile on the after sail of either ketch or schooner.
    I look forward to hearing about your test sails.

  • 12 Nov 2011 01:12
    Quote
    Reply # 748011 on 747855
    Anonymous member
    Rodney Whitworth wrote: I am not sure where I can find the photographs you mention of Badgers sails
    I wrote a piece about Badger's sails in JRA issue 50, January 2008. I thought there were some pics in the photo gallery, but found that there weren't – I've added some now.
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