Batten spec database

  • 21 Nov 2013 13:22
    Message # 1443163
    I just compiled this database using batten/boom/yard specs from the member database. I wanted an overview of the differencent choices members had made regarding batten strength/sizing. I added "breaking strength" (using my JR Calc) and "breaking strength to sail area ratio" (BS/SA), which is probably a non-optimal way of comparing but it's at least something. I'm open to suggestions/improvements.

    Here's the db:


    You can download the database by first opening it, then selecting File / Download as, and choosing an appropriate format.
  • 21 Nov 2013 20:36
    Reply # 1443549 on 1443163
    Well done, Oscar.  Good for you.  Do I take it that you have just analysed aluminium battens, to date?
    Last modified: 21 Nov 2013 20:39 | Annie
  • 22 Nov 2013 12:49
    Reply # 1444002 on 1443163
    Yup. Mainly because that was what I was curious about. I might add wooden and other material spars if/when I have the time.
  • 23 Nov 2013 19:45
    Reply # 1444723 on 1443163
    Oscar, you need to differentiate between flat and cambered rigs. Cambered rigs require stronger battens as they load the battens a lot more. This is because in a flat sail, the sail it's self offers some support to the batten and of cause the sail has less loading per square foot (reflected in less drive).

    In cambered sails, the batten receives no support from the sail, so must handle all the loading on it's own. Also because cambered sails produce considerably more drive, the loading on the batten is higher than it would be with a flat sail. Taken together, it means that if you have a cambered sail, you will need battens that are quite a bit stronger than what you'd get away with for a flat sail.

    You also need to consider stiffness/displacement. A stiffer boat/heavy displacement boat is going to impose larger rig loads all around owing to it's ability to stand up to the wind ie. the boat will heel much less for a given wind speed.


  • 24 Nov 2013 16:27
    Reply # 1445085 on 1443163
    You're right Paul, and those were all considerations when I started collecting the data. I however don't really know how I should relate batten breaking strength to SA/Disp, for example, I'm neither an engineer nor a math wizard. If anyone has any pointers/ideas/formulas I would gladly try to incorporate them.
  • 24 Nov 2013 18:46
    Reply # 1445135 on 1443163
    Is there a way to add Batten specs to the database?
  • 24 Nov 2013 19:53
    Reply # 1445182 on 1443163
    Edward, it should be an easy task for anyone who has write access to the mast database to copy/paste the data from my sheet. As Annie pointed out though, I've only input the aluminum batten data so far.

    Currently thinking about ways to relate batten strength to sail area to displacement.....
  • 24 Nov 2013 20:21
    Reply # 1445189 on 1445182
    Oscar Fröberg wrote:Edward, it should be an easy task for anyone who has write access to the mast database to copy/paste the data from my sheet. As Annie pointed out though, I've only input the aluminum batten data so far.

    Currently thinking about ways to relate batten strength to sail area to displacement.....
    Oscar, I don't really think that there is a reasonably simple way to factor in displacement except to be aware that heavy boats do impose larger loadings. Because even among heavy boats some are stiffer than others or harden up in different ways. For example, a Spray type hull behave more like a cat in that after about 5 -10 degrees of heel, she does not move. Proper Colin Archers are similar although they heel a bit more. Then you have a boat like LC. She heels readily to about 25 degrees but after that it would take a great deal more wind to heel her any more.

    I'd say, keep it simple and differentiate between cambered and flat sails with just warning that stiffer boats can create greater loadings.

    What we also need to do is find away to get members to update their profiles and enter their rigging details. So far this has been done by very few members.

    Last modified: 24 Nov 2013 20:22 | Anonymous member
  • 24 Nov 2013 20:56
    Reply # 1445203 on 1445189
    Paul Thompson wrote:What we also need to do is find away to get members to update their profiles and enter their rigging details. So far this has been done by very few members.

    Agreed. There's relatively little data to work with.

    I did come up with something though. By using the formula:

    Breakingstrength / Sailarea / sqrt(displacement)

    I get some kind of maybe useable numbers (rough guidelines). Most cambered sails seem to fall into the range of 0.8-1.2 whereas the flat ones are mostly between 0.4-0.7.

    I also updated the document to do the actual breaking strength calcs within the spreadsheet (for Version 1 I just used the JR Calc and copypasted the values from there) so that I could play around with numbers for my own sails. It seems to be pretty much in line with what I had researched before. Using 40x1.5mm battens for my 34m2 sail (3 tons displacement) would give a #2 factor of 0.87 (in the low range) but upping it to 45x1.5mm (as I would've done even without this experiment) gives a factor of 1.12.

    As Paul noted one should definitely take hull shape into account when using this data for anything other than to peak ones curiosity. Plus there is very little data to go on and I agree it would be great if we got more members to input their data to their profiles.

    Here's the updated Version 2.1 which includes my own conceived rig.
    Last modified: 24 Nov 2013 20:56 | Anonymous member
  • 23 Apr 2014 11:08
    Reply # 1542234 on 1443163
    There's further discussion in the Technical Forum e.g. here.
    Last modified: 23 Apr 2014 11:10 | Anonymous member
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