Thunderstruck

  • 05 Oct 2015 21:29
    Reply # 3561557 on 3329511
    Deleted user

    Hi Asmat. Hey, you've made great progress getting to La Corunna; congratulations. We had a slow trip down the French coast as you may have seen from our posts. La Rochelle is working out well. We should try to get together next season to compare notes, but no doubt you'll move on before we get to LC. Hope the mast wiring went well; let me know how you did it!

    Off topic, but just read your profile and see you have links with Hull where I was born. Interesting to see that XXX is a Wylo 32. The last time we sailed down the coast of Portugal we did so in company much of the time with a gaff-rigged Wylo 32. He'd wanted to use junk sails but decided ti stick with what he knew. Glad you made the jump. Ian and Kathy went on to sail round the world but found the gaff rig a pain at times.

    Last modified: 05 Oct 2015 21:37 | Deleted user
  • 05 Oct 2015 21:18
    Reply # 3561543 on 3329511

    Hello Brian, I'm reading your post with great interest: I'm berthed in La Corunna watching lighning flicker silently in the hills all around. We hoisted our new sails for the first time in Chichester Harbour just over 4 weeks ago and set off on our sea trials the next day, with numerous jobs still to be done. One of these was the bonding of our metal masts to the steel hull. That's going to be my first job in the morning.

    Cheers, Asmat


  • 04 Oct 2015 21:30
    Reply # 3559579 on 3329511
    Deleted user

    Hi Asmat, Arne

    I keep an eye on the Freedom web site (www.freedom.org) as my Freedom 39 has CF masts with an old (1988) lightning protection system which means both masts are linked by a flat. braided 1 inch wide cable to ground plates. Little else is linked in. So much stuff has been added over the years that I doubt the system would pass muster these days, given that specs have been uprated.

    http://www.marinelightning.com/FAQ.htm#CommonMisconceptions

    is a link that was posted recently. Its to a site that offers seemingly good advice. We had a few lightning episodes this summer on our cruise to La Rochelle, France, enough to get me reading up on what I should do...

    Last modified: 04 Oct 2015 21:35 | Deleted user
  • 06 May 2015 22:55
    Reply # 3334188 on 3329511
    Anonymous member (Administrator)

    Asmat,

    a boat needs not be a Faraday’s cage to keep you protected from the main strike of the lightning. Lots of wooden houses and churches, with their tall towers, have survived, thanks to the lightning conductors.

    I bet your boat will be better off than most with a good connection between the mast and the metal hull. A full Faraday’s cage setup may protect electronics on board better, but there are other ways of doing that sufficiently well.

    Arne

  • 06 May 2015 21:57
    Reply # 3334131 on 3329511

    Hi Arne, my aluminium masts will be earthed to my steel hull. I would still expect to suffer damage from as lightning strike in spite of this. My Wylo has a wood deck, so she is not perfect as a Faraday cage.

    It seems that carbon fibre aircraft components have a fine mesh of metal wire moulded in. The idea is that this forms a protective Faraday cage, at the cost of a small weight penalty.

  • 06 May 2015 20:46
    Reply # 3334056 on 3329511
    Anonymous member (Administrator)

    Asmat

    I would not be so concerned about those carbon battens. I would rather consider the mast, which you cannot reef away in a thunderstorm. Even an unstayed and not-conducting mast, made from dry wood or GRP, will have its tip on ground potential if it is equipped with a weather station or masthead light. Such a mast certainly would benefit from a real (25mm2) lightning conductor.

    I also wonder, since so many yacht rigs often are more or less covered in salt spray, that also the wood/grp mast top will be at ground potential, even with no wires running up the mast. Therefore it would make sense to fit a lightning conductor, anyway.

    The problem with carbon masts is that they are conductive enough to attract lightning, but have way to much internal resistance to lead the current to ground. It is therefore likely that they will be damaged by the heat, when struck, since the epoxy is not very heat resistant.

    I wonder how the makers of carbon fiber (composite) aeroplanes deal with this. Any suggestions?

    Arne

  • 06 May 2015 18:52
    Reply # 3333860 on 3329511

    The Sponberg site is interesting Brian. I didn't know lightning deflectors now have a rounded tip. I used to have one of those stainless steel toilet brushes. That seemed to work: I never got struck. I heard about a boat that had one fitted and was the only one in the marina to suffer a strike, though. Given the current (pun intended) state of knowledge, a witch's broom might be a better description.

    Cheers, Asmat

  • 06 May 2015 16:16
    Reply # 3333418 on 3329511
    Deleted user
    Asmat, our Freedom 39 from 1988 has CF masts. These are grounded. I believe it was standard practice even then. The linkage is 1 inch flattened coax, needs redoing.

    The masts also have 'Don't hit overhead power lines' stickers on them:-)

    This Spondberg link discusses damage to a CF mast after a strike.

    http://www.sponbergyachtdesign.com/threemastfailures.com/

    Google 'grounding yacht masts' gives lots of links. Dunno how you'd ground battens though.

    Last modified: 06 May 2015 16:35 | Deleted user
  • 06 May 2015 12:12
    Message # 3329511
    Does carbon fibre attract lightning? I'm considering reinforcing my upper battens with carbon and have been warned that ungrounded, it would increase the possibility of a strike. Googling has produced a lot of conflicting blah, which suggests that this may be a myth. A lot of boats have carbon fibre masts, including one I converted some time ago, but I made sure that it was well grounded.
       " ...there is nothing - absolutely nothing - half so much worth doing as simply messing about in junk-rigged boats" 
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