What size battens?

  • 21 Nov 2022 14:08
    Reply # 12996983 on 12986207

    Well chuffed that you're also going with bamboo! Also, very jealous you have your own supply and ability to harvest and dry it! Proper exciting.

    Best of luck,


    Zachary.

  • 21 Nov 2022 10:20
    Reply # 12996749 on 12986207

    Drill a hole in the bottom of the frisbees?

  • 21 Nov 2022 02:04
    Reply # 12996532 on 12986207

    It did cross my mind about the Frisbee's collecting water, maybe have less impact than leaving them in the dirt, who knows. I've also set a couple on some logs. It'll be a good experiment for sure. Plan B will be to go for the aluminum battens(thanks for your ideas on what size to use), be nice if the bamboo works out though..

  • 18 Nov 2022 16:09
    Reply # 12994316 on 12986207

    Jonathon,

    If your frisbees collect rainwater, won't that defeat their purpose?

    Otherwise, it's an interesting method of seasoning wood.

    Last modified: 18 Nov 2022 16:11 | Anonymous member
  • 18 Nov 2022 15:21
    Reply # 12994254 on 12986207

    Hi Jonathon,

    I have the same sail area as you plan for your boat (mine: 40 sq. m and yours: 429 sq. ft = 39,86 sq. m).  Therefore, I was a little curious to see how your planned battens are compared to mine (Ø32 mm x 3,5 mm), so I made a small Excel sheet for that.  But when I read your last posting, you have already chosen bamboo, so please just look at this as an exercise by a retired guy who has time for such things..

    My section modulus comparison shows that your options 1 and 2 are 1,81 and 2,65 times as strong as mine with respect to bending (when using same allowable stress).  I have not been on ocean crossings, and if I had, my 6 metres long battens might need to be stronger, but so far, my 32 mm x 3,5 mm battens have held.  So my hunch is that your option 1 will be strong enough with a good margin.

    Regards / Nils


  • 17 Nov 2022 23:09
    Reply # 12993560 on 12986207

    Thanks Annie, appreciate your reply. I read about your bent battens and agree the larger size is probably best, but not the cost. I decided to go back to basics and try bamboo! I cut 10 pieces today and will see how the drying goes. I'm using a traditional method favored by peasants so should be a good fit. If it works great, I'll see in a month!

    Post-harvesting transpiration is a technique used by peasants or indigenous communities. The procedure takes place on the bamboo plantation, and does not only dry the bamboo stems, it is also a traditional way to preserve bamboo from insect infestation.

    The freshly cut bamboo stems are placed on a stone (to avoid soil contact). The stem is placed upright, leaning against another bamboo tree with branches and leaves attached for about 3-4 weeks. This way, bamboo stems lose their humidity progressively true natural ventilation and transpiration true the leaves.

    I couldn't find any stones so I used some frisbees I had in my truck, should make the cut poles easier to find as well. I'll let you know how it goes...

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  • 16 Nov 2022 06:11
    Reply # 12991106 on 12986207

    Diameter is apparently more important than wall thickness.  After scrabbling about with my unit converter (why can't you guys go metric?), I would personally go for the larger size.  It's a pretty big sail and I managed to bend 38mm T6 battens - 1.5" - with a 325 sq ft sail in a 26 ft boat.

    Personally, I think you are more likely to get sudden wind acceleration coastal sailing, than offshore and that is the most likely stress to bend a batten. Apart from a bad gybe.

  • 11 Nov 2022 19:21
    Message # 12986207

    I'm getting ready to build a new cambered sail for my NA 29. Sail area is 429sq ft. I'm planning on using aluminum battens. I currently have two choices available locally;

    1. Schedule 40 6061 pipe Outside diameter 1.625" with a wall thickness of .140"

    2. Schedule 40 6061 pipe Outside diameter 1.90" with a wall thickness of .145"


    Planning some offshore passages. I'll be using Weathermax 80 as my sailcloth.

    which would you use..?

    Thanks, Jonathon

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