[Rhodes22-list] sailing and lightning

[Michael D. Weisner]

Ed,

The Admiral (read better half) and I have debated the necessity for lightning protection for years.  After a while, I finally decided to ground the mast on our R22 with a #4-gauge copper cable from the mast tabernacle through the cabin along the bulkhead post, under the cabin sole, to a 3-4 sq ft thin aluminum plate in contact with water inside the centerboard trunk.  All of these items were readily available at the time that I decided to ground the boat and I have no idea if it provides even a decent level of protection.  Once I had decided to try to protect the boat from lightning, it seemed better than nothing.  Maybe someone else can calculate what is needed.

The plate was affixed using several of the bolts holding the centerboard trunk cover (fiberglass), positioned so that it did not interfere with the board.  The plate was "sandwiched" between the trunk cover and the hull.  The plate was bent in an "L" shape with a small portion protruding into the cabin for cable attachment and the long portion of the "L", parallel to the centerboard when up, positioned between the board and the hull.  This required no new holes in the hull, was sealed by the centerboard trunk gasket and provided a fairly large surface in contact with the water.  The biggest problem was that there was no easy way to inspect or service the plate in this location, certainly not when in the water.  Corrosion has been a big issue with the plate over the years.  I am wondering if it requires replacement.  I also wonder if I have enough surface contact with the water.

Articles like the one below make me wonder if we really need a system:
http://www.sailnet.com/collections/articles/index.cfm?articleid=barron004
The problem is that a conductive protection system is thought to "attract" a strike.  From the above article:
  The thinking of the "unprotected" school is that by installing a direct path to ground, as in a lightning protection system on a boat, an invitation is being issued for a strike to come aboard. This is the great irony of deciding on lightning protection systems-unprotected boats may actually be struck less often, but when they are struck, they usually suffer more damage. A boat with a good lightning protection system, on the other hand, may actually have a greater likelihood of being struck, but the strike is dissipated and directed away, usually with minimal resulting damage.
To my knowledge, our R22 has never sustained a hit.  This may be due to several things, not the least of which is that our mooring is protected by very tall cliffs nearby and we are fair weather sailors.  Of course, should we be underway when a storm develops or at another location, this will be moot.  Clearly, we have been lucky.

Mike
s/v Shanghai'd Summer


From: "Tootle" <ekroposki at charter.net>
> 
> Where did it go?
> 
> Where is that question I posted?
> 
> Here is what started the question:
> 
> http://www.cdc.gov/nasd/docs/d000001-d000100/d000007/d000007.html
> 
> It say you should ground your mast.  But it does tell me how to ground the
> mast that I can figure out. So how do you ground a sail boat??
> 
> Bill Effros, you are the expert on this subject, aren't you?
> 
> So how do you ground a sail boat?  
> 
> John Lock, you are the current research expert.  What is the correct answer?
> 
> Ed K
> Greenville, SC, USA
> -- 
> View this message in context: http://www.nabble.com/Gone-sailing.-tf2016691.html#a5549206
> Sent from the Rhodes22 forum at Nabble.com.
> 
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