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Making CFRP battens

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  • 22 May 2012 20:52
    Quote
    Reply # 927722 on 926974
    Anonymous member
    Kurt Jon Ulmer wrote:
    David Tyler wrote:
    Will you do it, please?
    David.
    okay

    I will look forward to reading it as I'm sure it will be well and clearly reasoned.
  • 22 May 2012 04:06
    Quote
    Reply # 926974 on 925858
    Anonymous member
    David Tyler wrote:
    Will you do it, please?
    David.
    okay
  • 21 May 2012 21:11
    Quote
    Reply # 926622 on 911490
    Anonymous member
    Two days ago, I carried out the first stages of the repair.
    1. sanded the ends of the break down to a feather edge, over a length of taper of 200mm each side.
    2. inserted an alloy sleeve 750mm long, to keep the pieces lined up and to provide almost enough strength in itself.
    3. laid up three layers of carbon braid, 200, 300 and 400mm long. It's amazing how much resin even these small pieces can soak up.
    By now, the cure should be well enough advanced to sand the repaired portion to an even diameter, using a longboard. Then I can add an overall extra layer. Or two.
  • 20 May 2012 21:28
    Quote
    Reply # 925858 on 923751
    Anonymous member
    Kurt Jon Ulmer wrote:First, to David: Yes, someone has to be first. We all owe you a debt of gratitude, not mainly for breaking things, but for solving the unforeseens in new developments of the rig. You dare to invent, and then sail farther and harder than most of us. I wish you a quick and satisfying repair session.

    And responding to Arne:
    I agree with your analysis of loads and camber. Flat sails distribute strains.
    As a horse-and-carriage non-scientist cruiser, I'm willing to sacrifice some power for robustness. In racing, things should break from time to time, to ensure they're not over-built. But for our happiest cruising, things should break not at all. (A bend now and then is acceptable.)

    Many of my posts on this site have tried to influence other non-rocket-scientist
    sailors to stick to what is proven to be hardy, rather than to take up the promise of speed or windward wizardry.

    I can cite for my authority only the pleasant fact that mehitabel is a very robust and satisfactory cruising sailboat with flat-as junk sails. And not only downwind in the Trades.

    Cheers,
    Kurt
    Kurt,
    I think what the next magazine needs to contain is a well-written, well-argued article from you entitled something like "In defence of of the flat sail".
    Will you do it, please?
    David.
  • 19 May 2012 18:19
    Quote
    Reply # 925400 on 922889
    Anonymous member
    David Tyler wrote:Uh-oh. Battens 5 and 6 broke suddenly, close reaching in a 35 knot rain squall. They weren't bending, so gave no prior warning. Limping back to Mahurangi Harbour to think how to mend them.

    I've just managed to get online after several days away from the Internet.  (It's really difficult to find Internet access here in Canada).  Really, really sorry to hear about your battens, David, after all the grief they've already caused you.  But this is what you pay for being at the cutting edge of innovation.  No doubt you'll make new and stronger ones.

    The good news is that Tystie looks magnificent with her new sail!
  • 19 May 2012 10:04
    Quote
    Reply # 925171 on 911490
    Anonymous member

    I've started repairing the battens. There are nasty dry spots at the breaks. I'm blithely assuming that they broke at the weakest points, so everywhere else must be stronger, but I'll plaster more layers on these two so that all four top battens have been beefed up. They weren't flexing at all, so it's difficult to know how near to failure you are.

    Gary, yes, I was deliberately going out in as much wind as I could find, to load the rig as much as possible in controlled conditions, inshore. I think I would find it very difficult to repair battens as big as these, offshore, even if the weather was mild.
  • 18 May 2012 22:27
    Quote
    Reply # 924640 on 911490
    Anonymous member
    I suppose the good news is they failed now and not half way across the Pacific. Good luck with the repairs David.
    Regarding batten numbering, I would prefer to number from the bottom as well.
  • 18 May 2012 19:38
    Quote
    Reply # 924452 on 924161
    Anonymous member
    Peter Scandling wrote:

    David

    Did you vaccum bag the battens?

    Peter

    No, it was beyond me to set that up. The simple fact is that I bit off more than I could chew. I didn't have the working conditions and skill level to make a complete success of this, though I hope to salvage a partial success. As you get older, so you get wiser in some ways, dafter in others...
  • 18 May 2012 13:35
    Quote
    Reply # 924168 on 911490
    Anonymous member
    sorry to hear about the batons David ,I lost some battons in simular fasion hence changing to plastic waste water pipe ,if they flex too much stick a smaller one inside . engineeres  designe weakness into there machines to savguard them and save costs .    The chinese did the same , by putting weak rope on there sheetlets to save there battons ,I use builders multi plait nylon string but it has,ent broken yet, you just cant win em all .P/s at 35 kns you were covering some ground cheers .
  • 18 May 2012 13:17
    Quote
    Reply # 924161 on 911490
    Anonymous member

    David

    Did you vaccum bag the battens?

    Peter
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