Some sail modifications needed after 10,000 miles

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  • 31 Oct 2013 19:47
    Reply # 1425663 on 1419789
    Deleted user

    I have just picked up this thread as part of my catch up now that we are home from our cruise to New Caledonia on Footprints.  Although we only did 2500 miles compared to David Tyler's 10,000 I can at least report on how Footprints sail has held up. Of interest is that just about all of both ocean passages was with the sail to windward and therefore lying against the mast, (westerly winds going north, easterly coming back).

    First off the sail performed well on all occasions and generally proved easy to reef and unreef. I had no problems with excessive camber. We never had more than 30 knots of wind so the minimum number of panels I reefed down to was 4 panels. Being able to cant the sail across the mast for reaching and downwind work is a definite plus for this sail and significantly reduced helm loads and made the boat better balanced all round.

    Although I carried a spare batten I did not need to use it and both the carbon tube battens and the 3 alloy battens are still in one piece with no indication of bending or breakage despite several energetic crash gybes. I had thought about replacing the alloy tube yard before we went on the trip as it did have a bend in from last year and I had flipped the yard around so it would bend back straight. I never did replace it and it seems to have come through okay.

    There are several areas of chafe on the battens pockets in way of the mast and I have had to put a small patch on one of the sail panels where it obviously has gotten caught between the mast and a batten. The other small areas of chafe on the batten pockets I will also patch by gluing on some sail cloth. A lot of the chafe to the sail actually occurred one night when I was motoring in a zone of no wind but still rolly seas. I tried dropping the sail to reduce damage but found that the boat rolled even more, so I put half the sail back up. The flapping of the leech in the lower panels is a bit annoying but I could not find any way to prevent this happening, but thankfully there does not appear to be any damage as yet to the cloth.

    So all in all both boat and rig have held up very well to a double ocean crossing and I have only several hours of maintenance work required on the rig. It was interesting to note that Footprints was very much at the budget end of the cruising yachts out there and at 10 metres was one of the smallest. Quite a few people asked me ' what type of boat is that?' as they obviously could not get their heads around the unusual hull shape and the unstayed rig. However little Footprints and her junk rig managed to go all the places the bigger boats went so that is some satisfaction.

  • 28 Oct 2013 15:42
    Reply # 1422937 on 1419789
    Agreed, Arne, it's always good to have a choice of methods, and some are more suitable for some uses, others more suitable for other uses. But all of them will produce a workable sail and certainly all of them will produce a sail that's a lot more efficient than "white triangles" in terms of money spent/miles sailed, or crew effort/miles sailed, or any other measure of efficiency that you can devise.

    I thought that it was time that I made a scale drawing of how I would like to re-cut my sail panels, if I take the sail apart to improve the batten pockets. Now I know what I am talking about :-)

    It turns out that to maintain the maximum amount of power-producing rounding in the forward part of the sail, the curved edge should extend 4.5% of the chord outside of the straight line from corner to corner of the panel, with its maximum depth at 30% of the chord; and then, to take out the excessive cloth in the after part of the panel, there should be a concave curve with a depth of 0.75% of the chord, instead of a straight tangent from the forward curve to the after corner.

    It is this excessive cloth, and the resulting depth of camber being too far aft, that produces weather helm,and causes the panels to empty and fill with a Bang! in decreasing winds with a left-over sea. 

  • 27 Oct 2013 00:16
    Reply # 1421978 on 1419789
    Anonymous member (Administrator)

    David,

    since I have used fairly soft canvas for all my sails, I had forgotten that some uses Dacron. I can see the point you make that stiffer canvas needs a different method.

    And no, I certainly don’t need long-lived batten pockets for my own use, and I have no need to replace them easily. However, in this 10.000 N.Miles perspective, I thought that the two mentioned advantages with my method B could be useful for an ocean voyager; the quick fixing or replacing of b-pockets, and the well protected panel (joining) seam.

     

     

    However, I think we are arguing over rather minor details. In the big picture your rig is no doubt good for your use (as my rig is for mine). And I bet you, just like me, congratulate yourself each time you pass yachts with the crew struggling with risky and uncomfortable deck work J .

     

     

    Cheers to that!

     Arne

    Last modified: 27 Oct 2013 00:17 | Anonymous member (Administrator)
  • 26 Oct 2013 23:19
    Reply # 1421962 on 1419789
    Arne, the difference between your sail and mine - and it is an appreciable difference as far as this matter is concerned - is that you are using soft cloth and I am using hard dacron cloth. Your sail might look good, but mine does not, and will not, until I take some of the excess cloth out of the panels and change the method of making the pockets. I simply cannot get a good set to the panels under all circumstances, and method B is a major contributor to that. Either method C or method D will serve me better.
    Icannot understand why you make such a feature of being able to change the pockets. Have you ever done so? It should not be necessary unless you sail many ocean miles. I would not need to do so now, had I used method D in making the sail.


  • 26 Oct 2013 13:08
    Reply # 1421728 on 1420900
    Anonymous member (Administrator)
    David Tyler wrote:
     
    Performance, and Longevity, ahead of Looks. Method 'B' may have performance, but it has neither longevity or looks to commend it. It works as the "quick and dirty" way to make a sail, as you found at first, but it's time now to move on to better ways of working.

    Stavanger, Saturday

    Well, David,

    they say that beauty is in the eyes of the beholder. I admit that I think my sails look good, with or without a few wrinkles here or there. Take a look at Johanna’s sail on the “bad” tack, here and here. The wrinkles at the battens have to do with me not using broadseams to take in the slack. On Johanna I have slackened the sail 10cm along the battens to increase camber. BTW, Johanna’s sail was made by a sailmaker, so the batten pockets are ”conventional”. On later rigs (Edmond Dantes, Frøken Sørensen) I keep the sail a bit tauter along the battens. This mainly does away with the wrinkles, and also makes the vertical curve of the camber flatter  -  more “shelf-fottish”. Here and here are two photos of Edmond Dantes. Maybe I am a bit subjective, but I think this powerful sail looks great, even on the "bad" tack. The batten pockets, made with Amateur Method B, do harly differ from the sailmaker's pockets of Johanna, and  they certainly perform equally well. The batten pockets at the mast are  made of thick PVC and could, of course, be made from even stouter material, if needed.

     

    The first cambered panel sail, which I made for Malena in ’94, was assembled, using Amateur Method A (see JRA NL 30). This method surely was quick and dirty, with its protruding raw edges. Still, even though that sail never saw a sail cover, and was used a lot, it lasted for 17 seasons (see photos from the  Stavanger Rally 2010) and when it finally gave up, the seams, roping and batten pockets were still good.

     

     

    The Amateur Method B, on the other hand, where batten pockets are sewn on after the sail has been assembled, I now regard as a fully operational method. One big advantage over most methods is that the panel (joining) seam is so well protected, both from chafe and sunshine. In addition, this method lets one rip off a worn batten pocket in seconds, and sew on a new one on in a few minutes.

     

     

    As for the looks of the modified HM style sail plan that I use: One may like it or not. There is no use in discussing personal taste.

     

    Cheers, Arne

    Last modified: 04 Apr 2018 16:29 | Anonymous member (Administrator)
  • 25 Oct 2013 22:48
    Reply # 1421485 on 1421449
    Guy Bartholomé wrote:
    David Tyler wrote:Yes, that's the idea, but I would put the depth of camber much further forward, with a slight hollow in the edge of the panel aft, so as to ensure that the whole of the after half of the sail remains flat.

    Do you mean that you should put the maximal depth of camber less than 35% forward ? 
    Doing this do you want to increase the entry angle ? So what should be the best value of this angle ? 
    Is the "slight hollow" you talk about a little concavity in the aft end of the edge ?

    Best regards.
    35% would be OK, but not more, IMHO. Your sketch seemed to indicate more.
    Yes, a slight concavity, perhaps 1% - 2% of the chord. David Thatcher and I felt, when we had rigged our sails, that with a straight edge to the panel, perhaps the position of the maximum depth of camber was a little further aft than was ideal.
  • 25 Oct 2013 22:01
    Reply # 1421449 on 1421394
    Anonymous
    David Tyler wrote:
    Guy Bartholomé wrote:
    David Tyler wrote:
    I made the sail so that the broad-seaming forms a rectangular crossection to each panel. I would like to alter the sail so that the "shelf" at the top and bottom of each panel was at 30degrees to horizontal. Then it is easy to make the calculation - sin30 is 0.5, and the panel would be cut with a curve of half the required depth of camber, and the broad-seam would extend into the sail by the depth of camber, which would be half the depth of camber inside the straight line from luff to leech. Does that make sense? Slieve uses a 45 degree shelf, which is fine, but the 30 degree shelf is easier for a practical, hands-on sailmaker to understand and do, without making mistakes.


    If you had to build a new sail, you would make the broadseams like this... ?? 


    Yes, that's the idea, but I would put the depth of camber much further forward, with a slight hollow in the edge of the panel aft, so as to ensure that the whole of the after half of the sail remains flat.

    Do you mean that you shoultd put the maximal depth of camber less than 35% forward ? 
    Doing this do you want to increase the entry angle ? So what should be the best value of this angle ? 
    Is the "slight hollow" you talk about a little concavity in the aft end of the edge ?

    Best regards.
  • 25 Oct 2013 21:17
    Reply # 1421402 on 1421181
    David Tyler wrote:
    Paul Thompson wrote:David, if you use method "B" and PVC tube that is split as Slieve suggests and as I have done, it works perfectly. It's not method "B" that does not work, it's your implementation of it. Doubtless your method "D" will work better for how you are doing it but to me it seems an overly complicated way of doing things. Also if you sew the sail seam and sew the pocket on separately, you can replace the pocket without have to rip the sail seam.

    PS. I put my PVC over the pocket not inside as Slieve has done.

    OK, Paul, come back and tell me whether it's all still perfect after you've sailed 10,000 miles :-) That's what I'm reporting on. You don't know yet whether or not the edges of the PVC tube will chafe the pocket right next to the seam, which would be my guess in long term use.
    Regarding the 10 000 miles, a fair enough comment :-) However I'm not expecting to see chafe at the pocket by the seam. The tubes are a tight fit and are not in anyway loose. Once they are on they don't move. The fit is so tight that I use a large circlip pliers to open one end, force it on and the rest then rides over the batten (tube n pocket) to snap on.

    When making them, I cut the slot with a router. the ends of the slot and all edges are carefully rounded and smoothed. I don't have a photo but I'll take one when I go down to LC again.

  • 25 Oct 2013 21:03
    Reply # 1421394 on 1421327
    Guy Bartholomé wrote:
    David Tyler wrote:
    I made the sail so that the broad-seaming forms a rectangular crossection to each panel. I would like to alter the sail so that the "shelf" at the top and bottom of each panel was at 30degrees to horizontal. Then it is easy to make the calculation - sin30 is 0.5, and the panel would be cut with a curve of half the required depth of camber, and the broad-seam would extend into the sail by the depth of camber, which would be half the depth of camber inside the straight line from luff to leech. Does that make sense? Slieve uses a 45 degree shelf, which is fine, but the 30 degree shelf is easier for a practical, hands-on sailmaker to understand and do, without making mistakes.


    If you had to build a new sail, you would make the broadseams like this... ?? 


    Yes, that's the idea, but I would put the depth of camber much further forward, with a slight hollow in the edge of the panel aft, so as to ensure that the whole of the after half of the sail remains flat.
  • 25 Oct 2013 19:44
    Reply # 1421327 on 1420063
    Anonymous
    David Tyler wrote:
    Guy Bartholomé wrote:David,

    Thanks for all these precious informations.

     You propose little corrections on your sail, but  if you had to build a new sail which details would you eventually change ?

    What do you think about the broadseams of Slieve Mac Galliard as described in the pages 16, 17 and 49,50  in his public domain info ?
    What could be the avantages or disavantages of a smooth curve like the one obtained by the method of Slieve used in the top and the main panels ?  In other words, is there any avantage to make panels with deep broadseams going throught a part of the parallelogram ?
    May I ask you why you didn't use this deeper broadseam technic ?

    Have a good trip !

    Guy



    I made the sail so that the broad-seaming forms a rectangular crossection to each panel. I would like to alter the sail so that the "shelf" at the top and bottom of each panel was at 30degrees to horizontal. Then it is easy to make the calculation - sin30 is 0.5, and the panel would be cut with a curve of half the required depth of camber, and the broad-seam would extend into the sail by the depth of camber, which would be half the depth of camber inside the straight line from luff to leech. Does that make sense? Slieve uses a 45 degree shelf, which is fine, but the 30 degree shelf is easier for a practical, hands-on sailmaker to understand and do, without making mistakes.


    If you had to build a new sail, you would make the broadseams like this... ?? 


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