Quick question about tabling...

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  • 19 Apr 2017 18:38
    Reply # 4763738 on 4756626
    Arne Kverneland wrote:
    I don't insist anything, Scott...

    If I had plenty of sailcloth, but were struggling with finding useful webbing, then I would make and fit the needed tabling and use that to strengthen the edges 


    Arne - "Insist" definitely wasn't the word I meant, but is the one I typed. Sorry about that.  I don't think I've encountered anybody on this forum that does anything other than "suggest". 

    The post script answered my question though - thank you.

    Last modified: 19 Apr 2017 18:38 | Anonymous member
  • 18 Apr 2017 08:42
    Reply # 4758201 on 4754092

    I have been thinking about all the Bermudan sails I have had experience with, and which are subject to much higher loads than a junk sail. They have all had tabling made from the same fabric as the sail. Regardless, what we are after is something that works and has good longevity. And for me, if I am going to go to the effort and expense of building any sail, and it is in New Zealand, then the sail is going to have a sail cover to protect it from our harsh UV exposure.

    There is webbing, (seat belt webbing), in the high load areas of the sail on Footprints but this webbing is very localised. But the whole length of the leech and luff have sail cloth tabling and have so far shown no signs of failure. The yard and boom areas on the Footprints sail are a bit different than the norm in that both yard and boom sit in sleeves built into the sail.

    Regardless, it sounds as if Fantail has a new sail and I am sure you will be looking forward with excitement to fitting and using the sail.


  • 17 Apr 2017 20:59
    Reply # 4757275 on 4754092
    For what it's worth, and it's probably very little here, on sewn aircraft wings:
    • Tabling is used to feather point or linear loads into the body of the sail
    • Webbing is used to control stretch, and because it is effective it is never combined with tabling
    • Stitches are an insult to the integrity of the cloth; holes don't heal and all stitching must be justified
    • Various weights of cloth and different materials are used in the same sail.
    David, i wonder if the issue you've faced with sewing webbing is because you're mating it with Dacron. Clipper Canvas yields a bit.

    I suspect, but don't know, that the relationship between cloth layers and stretch is an inverse square law: twice the layers, one quarter of the stretch.

    Looking at Fantail's high peaking, short yard and abrupt upper leach angle changes, I see a more tension in the upper leach than on a H-M sail, and the upper luff likewise tensioned against the batten compression required in the upper panels. It's good to have the experience of the two Davids and their Fantail sails, as well as Fantail's existing sail, to see what's relevant here.


    Last modified: 18 Apr 2017 01:09 | Anonymous member
  • 17 Apr 2017 15:31
    Reply # 4756626 on 4756419
    Anonymous member (Administrator)
    Scott Dufour wrote:
    Arne Kverneland wrote:

    Gentlemen, you have convinced me that correctly fitted tablings take the loads around the sail’s edges well. Several Davids cannot be wrong.

     

     


    Arne,

    If you were making a new a sail, does this mean that you'd not use tape at all?  Are there any areas you'd still insist be reinforced with seatbelt material?


    I don't insist anything, Scott. The reason that I will still use webbing is that it comes on big rolls with the weave already in the right direction and with frail-free edges (= no need for hot-knives or wrapping), and I need them anyway to make the hoops for the battens to rest in. The combination of easy fitting and trouble-free service  of the webbing type boltrope still makes the choice simple to me.

    Arne

    PS: If I had plenty of sailcloth, but were struggling with finding useful webbing, then I would make and fit the needed tabling and use that to strengthen the edges  -  or I may rather fit a rope-type bolt-rope, as I used on Malena's first cambered panel sail (1994). That sounds like a slow method, but it isn't (see Chapter 5 of TCPJR).

      

    Last modified: 18 Apr 2017 10:18 | Anonymous member (Administrator)
  • 17 Apr 2017 13:11
    Reply # 4756419 on 4756214
    Arne Kverneland wrote:

    Gentlemen, you have convinced me that correctly fitted tablings take the loads around the sail’s edges well. Several Davids cannot be wrong.

     

     


    Arne,

    If you were making a new a sail, does this mean that you'd not use tape at all?  Are there any areas you'd still insist be reinforced with seatbelt material?

  • 17 Apr 2017 10:18
    Reply # 4756214 on 4754092
    Anonymous member (Administrator)

    Gentlemen, you have convinced me that correctly fitted tablings take the loads around the sail’s edges well. Several Davids cannot be wrong.

    However, when I read that sewing a tape (or webbing) on is not as easy as (cutting, wrapping and) sewing on the tabling, then I raise an eyebrow:

    I have sewn on ‘miles’ of webbing to serve as a boltrope, and to me this is by far the easiest job in the whole sailmaking process. The webbing I have been using on the last three sails, is a 2” wide polyester webbing, known as seatbelt webbing. This is indeed very easy to sew in, and my sewing machine doesn’t stall even with three layers of it, plus a couple of layers of sail cloth. This polyester webbing withstands the forces very well without stretching, unlike the nylon webbing I used on Johanna’s sail. After three seasons (2006), I beefed up the leech of Johanna’s sail by hand-stitching an old rope (halyard) to the backside of it. That sail is still operational.

    Arne

    PS: I once received a roll of 10cm wide tabling strips(tape) from the local sailmaker, meant to be wrapped over the edges of the sail, and then sewn on. This was of hard, stiff sailcloth and my sewing machine struggled with hammering its way through it. The seatbelt webbing I now use is not at all like that.


  • 17 Apr 2017 08:10
    Reply # 4756137 on 4754903
    David Thatcher wrote:

    Why introduce a different type of fabric which has different characteristics than the fabric the sail is made from. 


    It's a good question, David, and the reason I was considering it was that different characteristics may be useful in areas of the sail that have different purposes and are subject to different loads... but your point is taken. A lot of tabling went on today, and it's almost done. Unfortunately I've got to dash back to Christchurch tomorrow late afternoon, so no chance of testing it this week. :-(
  • 17 Apr 2017 03:45
    Reply # 4754903 on 4754092

    Based on the current longevity of the sail on Footprints I agree with David Tyler. Why introduce a different type of fabric which has different characteristics than the fabric the sail is made from. The sailcloth tabling on the Footprints sail was easy to do and has stood up to the test of time and use very well. My experience of sewing on tape is that it is not nearly as easy to sew as is the sailcloth, (or in your case the Clipper Canvas). In fact most of my sewing frustrations come from trying to sew tapes of various sorts.

    looking forward to seeing Fantail dressed in her new sail. 


  • 16 Apr 2017 09:52
    Reply # 4754249 on 4754092
    Thanks all... the end is in sight.
  • 16 Apr 2017 09:35
    Reply # 4754245 on 4754092
    Bryan Tuffnell wrote:If the luff and leach are taped in their entirety, is tabling also necessary?
    I would turn it around, Bryan, and say that if tabling is done properly, as sailmakers do it, with thread lines parallel to the leech, then taping is entirely unnecessary.
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