Flat, hinged or cambered?

  • 05 Jul 2021 08:17
    Reply # 10728460 on 10728437
    Paul wrote:
    LC's foresail is still the best setting sail I ever did and the variants that I've done based on it have been similarly successful. Low stress and sets well and possibly even more importantly, it was easy to get it set well.
    And that's the bit that I'm struggling to get Arne to understand and accept!
  • 05 Jul 2021 08:02
    Reply # 10728437 on 10728381
    Anonymous wrote:
    Paul wrote:
    David wrote:

    Here’s a rough and ready approximation of what I’d do for a new suit of sails for Taiko, starting with a clean sheet. The main yard is 4m instead of 5m, at an angle of 45˚ - 50˚ instead of 70˚. Similarly, the fore yard is 80% of the length of the old one. As you can see, this does not reduce the area. To keep the halyard close to the mast, the sail is rotated through 2˚ - 3˚ about the tack. This brings several more benefits with it, as the angles of THP and LHP are much improved, making them much more effective and less heavily loaded. The yard is lighter and under less bending load. Also, the centre of area moves forward, which helps with reducing the weather helm. I’ve put in two unsheeted battens so that the compression and bending load on each is reduced. These battens would probably not be hinged, but the lower ones would have hinges at their centre, at an angle of articulation of +/-12˚, with just a little barrel camber in the sail panels forward of the hinges, but not aft of them. 


    Those are of course pretty much LC's foresail.... I'd not put three upper panels in the foresail. Two panels is enough and it worked very well for LC.

    Indeed, that's true, Paul. I think it's because we were both designing a rig intended for extended passage making, with lower stresses on the rig and lower demands on the stamina of the crew in our minds. Things that I don't believe to be high on Arne's priority list.

    I agree, two head panels would probably have been enough for the foresail, except that aesthetically, I prefer both sails to look the same. Just possibly the three smaller head panels might be a reassurance when running under them in a F9, though.

    Agree, though I do think that two panels for the foresail is acceptable. Certainly the fact that the two sails are slightly different would not have perturbed the Chinese :-)


    LC's foresail is still the best setting sail I ever did and the variants that I've done based on it have been similarly successful. Low stress and sets well and possibly even more importantly, it was easy to get it set well.

    1 file
  • 05 Jul 2021 07:37
    Reply # 10728381 on 10727295
    Paul wrote:
    David wrote:

    Here’s a rough and ready approximation of what I’d do for a new suit of sails for Taiko, starting with a clean sheet. The main yard is 4m instead of 5m, at an angle of 45˚ - 50˚ instead of 70˚. Similarly, the fore yard is 80% of the length of the old one. As you can see, this does not reduce the area. To keep the halyard close to the mast, the sail is rotated through 2˚ - 3˚ about the tack. This brings several more benefits with it, as the angles of THP and LHP are much improved, making them much more effective and less heavily loaded. The yard is lighter and under less bending load. Also, the centre of area moves forward, which helps with reducing the weather helm. I’ve put in two unsheeted battens so that the compression and bending load on each is reduced. These battens would probably not be hinged, but the lower ones would have hinges at their centre, at an angle of articulation of +/-12˚, with just a little barrel camber in the sail panels forward of the hinges, but not aft of them. 


    Those are of course pretty much LC's foresail.... I'd not put three upper panels in the foresail. Two panels is enough and it worked very well for LC.

    Indeed, that's true, Paul. I think it's because we were both designing a rig intended for extended passage making, with lower stresses on the rig and lower demands on the stamina of the crew in our minds. Things that I don't believe to be high on Arne's priority list.

    I agree, two head panels would probably have been enough for the foresail, except that aesthetically, I prefer both sails to look the same. Just possibly the three smaller head panels might be a reassurance when running under them in a F9, though.

  • 05 Jul 2021 01:07
    Reply # 10727295 on 10725161
    Anonymous wrote:

    Here’s a rough and ready approximation of what I’d do for a new suit of sails for Taiko, starting with a clean sheet. The main yard is 4m instead of 5m, at an angle of 45˚ - 50˚ instead of 70˚. Similarly, the fore yard is 80% of the length of the old one. As you can see, this does not reduce the area. To keep the halyard close to the mast, the sail is rotated through 2˚ - 3˚ about the tack. This brings several more benefits with it, as the angles of THP and LHP are much improved, making them much more effective and less heavily loaded. The yard is lighter and under less bending load. Also, the centre of area moves forward, which helps with reducing the weather helm. I’ve put in two unsheeted battens so that the compression and bending load on each is reduced. These battens would probably not be hinged, but the lower ones would have hinges at their centre, at an angle of articulation of +/-12˚, with just a little barrel camber in the sail panels forward of the hinges, but not aft of them. 


    Those are of course pretty much LC's foresail.... I'd not put three upper panels in the foresail. Two panels is enough and it worked very well for LC.

    1 file
  • 04 Jul 2021 20:42
    Reply # 10726351 on 10712425
    Anonymous member (Administrator)
    Martin Simmons wrote:

    Arne,

    Presently I am seeking advice as to what may be alternatives for Taiko. No decision will be made until we get back to NZ where the availability of materials will be better than in French Polynesia .

    Certainly the wooden yards and battens need to be replaced and, if we are to retain cambered panels, some reworking of the rig will need to be made at this juncture. We liked the way Tystie’s  articulated battens popped backwards and forwards with each tack. I am uncertain if our masts are tall enough to use such system without the loss of sail area, which cannot be afforded. We will have to wait and see what those of greater knowledge consider best suited to our mast configuration.

    One thing is certain; we must have camber to sail well.

    Martin

    Martin.
    I wonder if you would let us know more details about your problems with the present sail? The couple of photos of your boat seem to indicate that the rig is not far from OK. However I am unsure of how you have rigged the YHP and LHP (THP?), how the sheets are configured and if you have now fitted Hong Kong parrels.
    It would be most useful if you also could show us the sailplan.

    I think the choice of using wood for boom, battens and yards is an unlucky one, so when you get access to aluminium, I suggest you switch to that material. Wood is too heavy, stiff and brittle for battens (..which I’m sure you have found out by now...).

    Btw, what sort of keel and rudder has your boat?

    Arne


    Last modified: 03 Feb 2022 14:58 | Anonymous member (Administrator)
  • 04 Jul 2021 13:22
    Reply # 10725161 on 461931

    Here’s a rough and ready approximation of what I’d do for a new suit of sails for Taiko, starting with a clean sheet. The main yard is 4m instead of 5m, at an angle of 45˚ - 50˚ instead of 70˚. Similarly, the fore yard is 80% of the length of the old one. As you can see, this does not reduce the area. To keep the halyard close to the mast, the sail is rotated through 2˚ - 3˚ about the tack. This brings several more benefits with it, as the angles of THP and LHP are much improved, making them much more effective and less heavily loaded. The yard is lighter and under less bending load. Also, the centre of area moves forward, which helps with reducing the weather helm. I’ve put in two unsheeted battens so that the compression and bending load on each is reduced. These battens would probably not be hinged, but the lower ones would have hinges at their centre, at an angle of articulation of +/-12˚, with just a little barrel camber in the sail panels forward of the hinges, but not aft of them. 


    1 file
  • 30 Jun 2021 01:24
    Reply # 10712425 on 461931
    Deleted user

    Arne,

    Presently I am seeking advice as to what may be alternatives for Taiko. No decision will be made until we get back to NZ where the availability of materials will be better than in French Polynesia .

    Certainly the wooden yards and battens need to be replaced and, if we are to retain cambered panels, some reworking of the rig will need to be made at this juncture. We liked the way Tystie’s  articulated battens popped backwards and forwards with each tack. I am uncertain if our masts are tall enough to use such system without the loss of sail area, which cannot be afforded. We will have to wait and see what those of greater knowledge consider best suited to our mast configuration.

    One thing is certain; we must have camber to sail well.

    Martin

  • 29 Jun 2021 21:50
    Reply # 10712002 on 461931
    Anonymous member (Administrator)

    Martin,
    I regret now that I was so slow with finishing the Chapter 7 about rigging the sail. That chapter was only uploaded in September last year....

    Are you still thinking of changing to hinged battens ?

    Arne

    Last modified: 29 Jun 2021 22:49 | Anonymous member (Administrator)
  • 29 Jun 2021 19:19
    Reply # 10711600 on 10707443
    Deleted user
    Anonymous wrote:
    Anonymous wrote:

    As for Martin Simmons(?) and his Taiko, I have no idea. I don’t know his boat and have never been contacted by Martin.

    Arne


     At some point it would seem Martin found your notes Arne.

    "I can say now that If I had read all of Arne Kverneland's published files from the outset it would have saved me much angst." - Martin Simmons

    Quote lifted from his blog here.

    I downloaded, printed and perused most conscientiously The Cambered Panel Junk Rig.

    I then set about building cambered sails of the same dimensions as our flat sails in order to use the same battens and yards. What I did not appreciate was that the loads on the yards would be so great and that aTHP, under enormous tension, would be necessary. Arne’s files that would have saved me angst were his later additions of fixes and improvements. The same could be said of Paul Faye’s account of changing to cambered panels. I remain unhappy with the tension in the upper sections of the sails, though Paul Thompson’s idea of creating drift by moving the standing part of the halyards aft, has ameliorated the problem. It must be said that Taiko is sailing well under her current rig, she is no slouch if she is able to cover a thousand miles in  one week of SE trade wind sailing. Furthermore, there have been no problems with the sails themselves, only running rigging and mast chafing and yard failure.

    More will be written about our experience on our eventual return to NZ.

    Last modified: 29 Jun 2021 19:41 | Deleted user
  • 29 Jun 2021 13:39
    Reply # 10710714 on 461931

    Mark,

    Yes, you're broadly correct.

    • AR: higher for Weaverbird, a nippy little cruiser/racer; lower for FanShi, a comfortable cruising home.
    • Sending battens from UK to NZ, the maximum length is 3m. Annie needed 5m, so for best economy, for both buying tube and the shipping cost, I elected to send 3m and 2m pieces. Because there is a lot of balance, for ease of handling, the hinge has to be aft rather than forward. What I should have done is bitten the bullet, accepted some wastage and sent all as 2.5m lengths. That would have been better in all respects. Weaverbird has hinges at halfway and further forward, because there is very little balance, the mast needing to be well forward to suit the internal layout. 
    • Don't read too much into the shapes of the upper panels. But the principle factor in the decision making is evening out the changes of direction in the leech, so as to share out the compression evenly.
    • Both luffs are designed straight, however they may look in the photos.
       " ...there is nothing - absolutely nothing - half so much worth doing as simply messing about in junk-rigged boats" 
                                                               - the Chinese Water Rat

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