High Aspect Ratio how high?

  • 04 Sep 2020 18:52
    Reply # 9212487 on 9211587
    Anonymous wrote:

    Have a look at JRA NL21 pp 24-25 for a description of this way of sheeting to the windward side with a rope span.

    I couldn't get your link to work David.  Hopefully this JRA NL21 pp 24-25 will work for anyone else interested.
    Last modified: 04 Sep 2020 18:52 | Anonymous member
  • 04 Sep 2020 10:24
    Reply # 9211587 on 9206692

    Have a look at JRA NL21 pp 24-25 for a description of this way of sheeting to the windward side with a rope span.

    Last modified: 04 Sep 2020 19:47 | Anonymous member
  • 04 Sep 2020 06:56
    Reply # 9211280 on 9206692

    David, thank you very much for such a detailed explanation. Now, I think, I understand much better issues regarding the JR sheeting to avoid some basic traps my first setup. I know it is a continuous process and that's a part of the fun. 

  • 03 Sep 2020 08:26
    Reply # 9208978 on 9206692

    I'm in favour of some vertical separation of the deck blocks, mainly so that the parts of the sheet don't rub against each other, but the topmost block must always be such that all parts of the sheet lead downwards from the sail. I don't see how a tower can be used, if this is the case.
    I put the topmost block on a fixed rope span so that no rigid hardware needs to be added, but it is always below the clew of the sail. If an adjustable rope span is fitted, that topmost block can be higher when under full sail, but then the span needs to be shortened when reefs are taken. Something like this, or putting the sheet blocks on a traveller that can be hauled up to windward, are better ways of sheeting a high AR sail than a tower, I think.

  • 02 Sep 2020 21:02
    Reply # 9207955 on 9206753
    Anonymous wrote:

    Mostly because chinese sheeting gets less effective, the higher you go with the AR. Those tall bermudan sails rely on a lot of sheet and kicker tension, opposed by the tension in the forestay, to minimise twist. 
    With a JR, and high AR, all we can do is sheet the upper part of the sail to the windward side, which is effective, but decreasingly effective as the vertical component of sheet tension increases and the horizontal component decreases.

    Thanks, do the sheet "towers" help to some extend?


  • 02 Sep 2020 11:29
    Reply # 9206753 on 9206692

    Mostly because chinese sheeting gets less effective, the higher you go with the AR. Those tall bermudan sails rely on a lot of sheet and kicker tension, opposed by the tension in the forestay, to minimise twist. 
    With a JR, and high AR, all we can do is sheet the upper part of the sail to the windward side, which is effective, but decreasingly effective as the vertical component of sheet tension increases and the horizontal component decreases.

  • 02 Sep 2020 10:50
    Message # 9206692

    Hi, the sail plan, as well as mast height for my new Caravelina is still not finally decided - open. As Caravelina is to be junk Mini 650 cruiser, I give a lot of attention to class MIni 650. They have main sailes almost rectangular, with plenty of full length battens and aspect ratio around 3,5 - 4. Why I should keep my junk sailes not much more then AR 2,5? 

      

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