[Alberg30] Lightning protection

[John Birch]

It would seem there are as many opinions as there are sailors - we have a copper pipe which connects below the sole from the mast to the engine and a second copper pipe which runs under the sheer inside the boat connecting the shrouds, stanchions to the main under sole pipe. I have often thought about connecting them to a larger grounding bronze plate as the two blade prop only works out to about 1.5 sq feet. Problem is of course hydrodynamic drag on an external plate if one were located under the mast. I feel from my reading it would need to be about 3 sq feet minimum which is not a small item - even if one made it a few inches wide and several feet long the sailing performance would be impaired. 

I am not sure if the above would really fully protect a boat as we actually watched a 50' IOR boat at our club get hit and she was fully grounded - the damage was huge - chunks blown out of the rudder, out of the hull at the chain plates which were grounded - and she had several connections to her huge keel bolts. Lightening goes where it wants and this boat was hit by a heavy direct hit - the lightening arched throughout her rig - it was awesome - fortunately no one was aboard during the hit. She had to be hauled and was in the shop for a month.

So can one realistically expect to get protection on a glass encapsulated keel boat with the minimal size of any plate one could offer up if a "protected" external keel boat wasn't protected?

I don't know the answer - but I suspect it is no.

Look forward to the discussion.

Fair winds and a lightening free summer.

Cheers,

John
  ----- Original Message ----- 
  From: Brian and Elaine Timmins 
  To: public-list at alberg30.org 
  Sent: Friday, March 15, 2002 7:15 AM
  Subject: Re: [Alberg30] Lightning protection


  I don't think the bow strip would make the perfect lightning ground by any means (IMHO). Maybe if you reworked the connection of this strip to the stemhead and insured a good clean electrical connection to the forestay AND did something to radically increase the size of the surface of the strip in the water., then maybe. I'm no expert in this field but my feeling is that if you took a hit and the current traveled down this strip, it would probably blow the strip off the boat.  The best looking removable protection I've seen on the web is at:  http://www.strikeshield.com/product.html 
  I don't mean to endorse their product, I just like the looks of it.  If nothing else, they have some good reading on the topic.
  Brian    #497
    ----- Original Message ----- 
    From: George & Kathy White 
    To: Alberg30 Mail 
    Sent: Thursday, March 14, 2002 8:21 PM
    Subject: [Alberg30] Lightning protection



    A posting to this mail group in 1999 suggested all Alberg 30's are lightning grounded by virtue of the stainless strip running from the stemhead down to about 3 feet below the waterline.  It connects to the forestay and thereby providing a grounding from the masthead to the water.

    Any comments as to whether this should be sufficient and what alternatives there might be.


    George and Kathy White
    Close Harmony # 637

    email: salty at ns.sympatico.ca
    Telephone: 902 893 1080
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