Forgot password

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

  • 17 Nov 2011 20:50
    Quote
    Reply # 752933 on 752804
    Anonymous member
    Annie Hill wrote:Don't forget that the Odyssey has one shiny side and one matt, which you might want to take into account, when laying out the cloths.

    Yep, I got confused. Luckily it doesn't look too bad...he said.
  • 17 Nov 2011 18:24
    Quote
    Reply # 752804 on 746824
    Anonymous member
    Don't forget that the Odyssey has one shiny side and one matt, which you might want to take into account, when laying out the cloths.
  • 17 Nov 2011 10:55
    Quote
    Reply # 752326 on 750735
    Deleted user
    David Tyler wrote:
    Peter Manning wrote:I don't think that the performance (of my wingsail) 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.

    David, you made this comment in an earlier posting and as I have a big single sail, fanned and cambered in the lower panels which you very kindly made for me several years ago for my boat Malliemac, I wondered if you could clarify your comment that this type of sail is not entirely suitable for ocean cruising. I can understand that this sail may not be suitable for southern ocean sailing but apart from that why do you express concerns about its suitability for cruising other oceans of the world. I am hoping to sail at least the Atlantic in due course and maybe venture into the Pacific if time and health permits. I would be helpful to know what aspects need careful attention.
    Peter,
    My chief concern was with the difficulty of reefing a single sail down to storm-sail proportions. Two panels of one of the sails in a two masted rig might be appropriate for a run or reach in gale force conditions, but two panels of a single sail is likely to be too much. There are solutions – look at PJR Fig 15.2 – but also note the text " ... not needed for ordinary cruising, but could be worth its place for anyone tackling the Roaring Forties". 
    Also, note my use of the past tense – "didn't feel". Bear in mind that when I converted to ketch rig, I was planning for the trip from Cape Town to Perth via the Roaring Forties. That didn't come to pass. I think that the ocean passage making that I have actually done could have been done with the single sailed rig, and that Malliemac with the single sail will be able to do the standard North Atlantic circuit. 
    I think it's a question of the proportion of total sailing time that is likely to be spent in strong wind conditions. The occasional moderate gale will be manageable in Malliemac with the rig that she has. Gales coming one after the other would be wearing on the crew, not least because of the amount of physical work that would have to be done in managing a big sail. 
    David, Thanks for the clarification and the solutions. Going to step the mast soon - getting there, slowly.
  • 16 Nov 2011 13:46
    Quote
    Reply # 751458 on 746824
    Deleted user
    Thanks Annie, David for answering my post. Gives us something to chew on..
    Our shipment of Odyssey is on its way, 90m of burgundy, sometime in the summer ahead we'll start cutting and sewing. May even have enough left over for a dinghy sail.

    PS. I prefer the term 'shelf foot' to 'lens' to describe that type of camber construction, in one of the pics of Badger, her sails look like giant bookshelves to me.

    Re: breaking battens, we intend to use aluminium tubing so maybe the chances of breakage is much slimmer.
  • 15 Nov 2011 20:51
    Quote
    Reply # 750735 on 750378
    Anonymous member
    Peter Manning wrote:I don't think that the performance (of my wingsail) 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.

    David, you made this comment in an earlier posting and as I have a big single sail, fanned and cambered in the lower panels which you very kindly made for me several years ago for my boat Malliemac, I wondered if you could clarify your comment that this type of sail is not entirely suitable for ocean cruising. I can understand that this sail may not be suitable for southern ocean sailing but apart from that why do you express concerns about its suitability for cruising other oceans of the world. I am hoping to sail at least the Atlantic in due course and maybe venture into the Pacific if time and health permits. I would be helpful to know what aspects need careful attention.
    Peter,
    My chief concern was with the difficulty of reefing a single sail down to storm-sail proportions. Two panels of one of the sails in a two masted rig might be appropriate for a run or reach in gale force conditions, but two panels of a single sail is likely to be too much. There are solutions – look at PJR Fig 15.2 – but also note the text " ... not needed for ordinary cruising, but could be worth its place for anyone tackling the Roaring Forties". 
    Also, note my use of the past tense – "didn't feel". Bear in mind that when I converted to ketch rig, I was planning for the trip from Cape Town to Perth via the Roaring Forties. That didn't come to pass. I think that the ocean passage making that I have actually done could have been done with the single sailed rig, and that Malliemac with the single sail will be able to do the standard North Atlantic circuit. 
    I think it's a question of the proportion of total sailing time that is likely to be spent in strong wind conditions. The occasional moderate gale will be manageable in Malliemac with the rig that she has. Gales coming one after the other would be wearing on the crew, not least because of the amount of physical work that would have to be done in managing a big sail. 
  • 15 Nov 2011 20:14
    Quote
    Reply # 750686 on 750368
    Anonymous member
    Gary King wrote:
    David,
    I was intending to make our sails with a horizontal cut, each panel is one sheet, cut like the Tom Thumb drawing you have, somewhere (I've downloaded it anyway), since the Odyssey I've ordered comes wide enough. But I noticed all the shelf footed sails you've been designing have been vertically cut.
    Seems like a lot more sewing for an amatuer sailmaker, is it necessary?

    Gary,
    It's good sailmaking practice to align the threads in the cloth to the load that is to be applied, within about 10 degrees or so. If you look at a bermudan mainsail closely, you will see that the threads are parallel to the middle of the leech, parallel to the straight line between head and clew, and at an angle to the leech near the head and clew. 
    In the JR, we are applying the load of the sheet via the sheet spans, at varying angles to the leech. In the lower part of the sail, there is little sheet loading, and the direction of that loading is variable. In the upper part of the sail, the loadings are higher, and tend to be in line with the leech.
    That suggests to me that in the lower part of the sail, we can give more weight to other factors when choosing how to align the cloth. The chief of these is that a seam is weaker than the cloth. Using Odyssey, a panel can be made without seams, and with its weft threads at about 10 degrees to the leech, which is satisfactory on all counts.
    In the upper part of the sail, and certainly in the top two panels, it becomes more important to align the cloth with the leech. With Odyssey, this can still be done with a one piece panel, at the expense of a little more wastage. However, I think it's better to lay the cloth parallel to the leech, in the top panel at least, because the head of the sail should have some rounding applied to it, and a seam meeting the head allows some broad seaming to be applied, to push the resultant camber further back into the panel. Without broad seam, that camber can lie too close to the yard (but I'm being a bit perfectionist there).

    I have used the vertical cut when using polyester sailcloth, 36" / 920mm wide, because it isn't wide enough to cut a complete panel, and vertical seams are better than horizontal seams in that they can only split over a limited length; and also to be able to use the broad-seam method of adding 3D shape. Vertical cut also wastes the absolute minimum amount of cloth, when care is taken over the unrolling and cutting process.

  • 15 Nov 2011 20:08
    Quote
    Reply # 750679 on 746824
    Anonymous member
    A few points here that I would like to give my two penn'orth on.

    Sewing the sail.  I don't know how big Maddog's sail is, but I found no real problem moving my sail around on a chipboard table, which was rough compared with a salmaker's floor.  At first I rolled the already-sewn material into a tight tube, but later found it was easier simply to shove the sail about.  A smooth surface would have made it easier.  I sewed a teardrop to a panel, then attached the next panel and then put the full-length batten pocket along the centre of the teardrop.  That way I never had more than a panel's width to push through the throat of the machine.

    Vertical panels  The idea of sewing vertical panels is to limit damage should the sail tear.  'Should the sail tear' is the phrase to bear in mind.  Something stretchy and strong like Odyssey, with its in-built reluctance to fraying is pretty tough stuff, certainly when new.  Any tears are likely to be produced by a broken batten.  A suggestion would be to run several vertical rows of stitching on each panel so that if the fabric did tear, they would limit its extent.

    Jiblets, wingsails, jointed battens.  KISS works best for low-budget, long-distance, lazy voyagers.  Complexity is fine if you have workshop access, your sailing is largely-inshore, and you are an energetic project-person.  Draw a scale and decide where you lie along it. 

    Single vs multi masts  One of the problems with a very big, single sail, offshore, is that the long battens can start dragging through wave tops in a large swell.  If anything goes wrong, eg a broken batten, there is a lot more sail to manhandle.  The mast is taller.  It is arguable that a second mast provides security in case one breaks.  In spite of the boat being extremely unbalanced one sail will still be better than two.  Of course, if you lose one mast you may well lose two.  One mast is simpler, the weight is further aft, which keeps the foredeck easier for anchor work and the boat - I am told - will sail better to windward.

    Blanketed foresail  By the time this is happening, drop a few reefs and harden it in.  You will go just as fast and the foresail will act a bit like an air-rudder to reduce yawing.  A lot cheaper and easier than a boom brake which will put horrid loads on the boom.

    Competitive  I keep hearing economists talking about the need to be more competitive,which seems to mean producing the most product for the least cash outlay.  I would suggest that the existing junk rig is already very competitive :-)
  • 15 Nov 2011 12:44
    Quote
    Reply # 750404 on 746824
    Anonymous member
    In response to David's comprehensive notes about the pros and cons of a wing sail, I wrote:  "Simple rigs for simple sailors.  That's me!"  I should make clear to Rodney that I was only commenting on a wing sail, a possibility that I raised almost in order to see it eliminated for him.  Rodney's original question was about: split rigs, cambered panels or jointed battens and indeed sloops, ketches and schooners as possibilities for his yet to be purchased boat.   It is still all to play for in all those areas.  I spoke earlier to Rodney and suggested that he consider buying an existing junk rigged sloop at modest cost and go sailing.  I fear that is too simple ... ! He has the engineering and creative bit between his teeth.  I wish him well and will watch with interest. 
  • 15 Nov 2011 12:20
    Quote
    Reply # 750400 on 750396
    Deleted user
    Gary Pick wrote:Are you going cambered Gary?
    Yes, cambered, using shelf footed panels.
    I was having trouble you guys talking "lens" shape earlier when I had the vision of the David's tuck panel "shelf foot" look alike my in head.

    Tried to post a picture, but failed, doesn't seem to work anymore :(
    Last modified: 15 Nov 2011 13:12 | Deleted user
  • 15 Nov 2011 11:52
    Quote
    Reply # 750396 on 750368
    Anonymous member
    Gary King wrote:
    David,
    I was intending to make our sails with a horizontal cut, each panel is one sheet, cut like the Tom Thumb drawing you have, somewhere (I've downloaded it anyway), since the Odyssey I've ordered comes wide enough. But I noticed all the shelf footed sails you've been designing have been vertically cut.
    Seems like a lot more sewing for an amatuer sailmaker, is it necessary?

    Are you going cambered Gary?
       " ...there is nothing - absolutely nothing - half so much worth doing as simply messing about in junk-rigged boats" 
                                                               - the Chinese Water Rat

                                                              Site contents © the Junk Rig Association and/or individual authors

Powered by Wild Apricot Membership Software