Proposal for Variable Camber

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  • 12 Jan 2015 23:22
    Reply # 3195473 on 1441932

    Dmitry Orlov is working on a new boat and planning on trying out the lace-up camber idea. Worth a read over at his blog Quidnon, he has a nice illustration of the lace up camber idea. 

    I really like how there's so many innovative ways to create camber including barrel, batten-shelf, piano hinge (mingming style), hinged battens, and now this lace up. It would be nice to see a write up instruction and comparative analysis in construction, performance and durability in some future document.

    Last modified: 12 Jan 2015 23:23 | Anonymous member
  • 08 Dec 2013 23:56
    Reply # 1454202 on 1441932
    Touché... your polite little elbow-jab in the ribs may be enough to make me bring out all those sketches I started.
    KJU

  • 07 Dec 2013 09:19
    Reply # 1453498 on 1449563
    Kurt Jon Ulmer wrote:If there were a robust and truly workable solution, I'd be quite willing to admit the need!
    Kurt
    Ah. But 'tis Neccesity the mother of Invention, and not the other way around!  

    8)

    Dave Z
  • 02 Dec 2013 08:32
    Reply # 1449563 on 1441932
    If there were a robust and truly workable solution, I'd be quite willing to admit the need!
    Kurt
  • 30 Nov 2013 03:43
    Reply # 1448603 on 1448417
    Kurt Jon Ulmer wrote:I don't think I'd choose a fabric for stretchiness. As with battens, there'd be most camber when I want least.
    Kurt
    Thanks, Kurt.

    I'm finding it amusing that the two camps actually agree that there is no need for variable camber, but for the very reasons (taken together) that one might want to vary it!

    This has been very educational, everyone. Thanks for your input!

    8)

    Dave Z
    Last modified: 30 Nov 2013 03:47 | Anonymous member
  • 29 Nov 2013 18:55
    Reply # 1448417 on 1441932
    I don't think I'd choose a fabric for stretchiness. As with battens, there'd be most camber when I want least.
    Kurt
  • 29 Nov 2013 06:46
    Reply # 1448220 on 1448100
    Kurt Jon Ulmer wrote:Hi Dave,
    Top Gun is soft, but not particularly stretchy. I chose it for durability above all, and for 'give' compared to hard dacron sail cloth. Performance, as you might guess, is good enough and not the main thing. Likewise, our camber is not optimum, but is present.
    Cheers,
    Kurt
    Thanks, Kurt! 

    How about next time? Would you like a little more stretch in your flat-cut sails? Or do you prefer them, as is?

    BTW, as you can infer from our choice of hull, we, too are big fans of Good Enough!

    Dave Z
  • 28 Nov 2013 18:26
    Reply # 1448100 on 1444388
    Dave Zeiger wrote:Hi Kurt,

    I just reread your article on the merits of flat-cut sails (awesome!)...

    Did you use acrylic, or other stretchy fabric for your sails? If so, do you feel that its inherent camber contributed to your performance? If you were building again, would you consider stretchy fabric?

    Dave Z
    Hi Dave,
    Top Gun is soft, but not particularly stretchy. I chose it for durability above all, and for 'give' compared to hard dacron sail cloth. Performance, as you might guess, is good enough and not the main thing. Likewise, our camber is not optimum, but is present.
    Cheers,
    Kurt
  • 24 Nov 2013 16:23
    Reply # 1445082 on 1445000
    Oscar Fröberg wrote:
    I've read about this elsewhere too. Expanding on it a bit, how about being able to lower the whole sail down close to deck level when sailing an extended period of time on one tack? As I'm visualizing it, it would require having a running tack line and mast lift.

    A watersail of some sorts might still be a better (easier) option, compared to having to have an unneccesary amount of running rigging.
    Yes. Taking the first reef upwards is the well-documented Chinese way to tackle this. (Adding an extra sail isn't).
  • 24 Nov 2013 13:59
    Reply # 1445000 on 1443172
    Mark Thomasson wrote:

    if I can draw on a miss-spent youth of windsurfing - where the power of the sail is immediately felt:

    - Blocking the gap between the base of the sail and the board was like turning on a turbo.  I see you have a big gap between boom and deck, so suggest try fitting a 'water sail'  for light winds. 


    I've read about this elsewhere too. Expanding on it a bit, how about being able to lower the whole sail down close to deck level when sailing an extended period of time on one tack? As I'm visualizing it, it would require having a running tack line and mast lift.

    This would of course also require removing the lifelines, but I've already had them removed before and I actually preferred not having them there. It felt easier and to move about the deck, without them restricting your movements beyond the rail. I did put them back last summer because of my SO, who I concluded would percieve them to be safe/comfortable. And they are great for hanging clothes/towels to dry. :) Point being that with decent grabrails combined with moderade bulwarks, lifelines are mostly useless and in many cases dangerous (the illusion of safety). Speaking of which, my dad fell through his lifelines last spring when doing deckwork while his boat was on the dry (the stanchion base came off and bent). Fortunately there was enough snow on the ground so he didn't hurt himself too bad.

    A watersail of some sorts might still be a better (easier) option, compared to having to have an unneccesary amount of running rigging.
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