[Public-List] lightning protection & grounding plates

[Roger L. Kingsland]

Dan,

I started to write about my "porcupine ball" LPS (lightning protection
system) then the old memory kicked in and I realized we hashed this stuff
out in 2004 and there is a wealth of posts on the subject in the archives
starting here
http://lists.alberg30.org/htdig.cgi/public-list-alberg30.org/2003-August/037
683.html and continuing through several posts (just click "next message" at
the top) including a scientific explanation of porcupine balls that can be
found at
http://lists.alberg30.org/htdig.cgi/public-list-alberg30.org/2003-August/037
693.html.

Oh my gosh!  I just realized everything I/we have posted on "the page" is in
these archives.  How embarrassing; please don't tell my wife.

Roger 148  


-----Original Message-----
From: public-list-bounces at lists.alberg30.org
[mailto:public-list-bounces at lists.alberg30.org] On Behalf Of Gordon Laco
Sent: Thursday, March 06, 2008 1:46 PM
To: dlandrigan at landrigan.net, Alberg 30 Public List -- open to all
Subject: Re: [Public-List] lightning protection & grounding plates

Hi Dan - 

This comes up regularly... The simple answer is there is no simple answer.

Common engineering wisdom goes like this:

If your rig is thoroughly grounded, you are more likely to get hit but less
likely to be damaged seriously.  If your rig is poorly grounded, you are
less likely to be hit but if you are hit, it may be worse.

I have looked, and can report that you can find 'scientific' evidence to
support both grounding and not grounding.

What do we do?  Well first I'll say that I am never comfortable when in a
thunderstorm because of the risk of a lightening strike.  I rationalize my
concern (fear?) like this:

The energy of a strike will tend to seek the most direct route to the water.
I hope that would be down the forestay to the bowplate then down the keel
band to the water.  We also snap a 6' length of 1/4" chain onto the backstay
and toss the end overboard.

I know of two stories first hand were people were killed by strikes on
yachts; one poor fellow was standing in his cockpit with the mast down and
was hit directly (the charge went through him to the engine and blew out the
through hulls.  The rest of the people had a bad time trying to revive him,
put the fire out and stop the leaks...)

The second fatality story involved a yacht being struck, and the poor guy in
the cockpit had his leg muscles make an involuntary jump - he went overboard
and drowned.

I hate those stories.

To balance them, I know of two other boats both of which were struck; in
both case there was no damage other than the electronics being blown out.
One was obsessively grounded and the other was not grounded at all.

So, who knows what is best to do?





> 
>  Quick question for you more experienced sailors. What protection do  
> you take against lighting strikes?
> 
> 
>  We had a rigging inspection done in preparation for spring, and the  
> inspector noted that we had no ground to the mast. But he said there  
> was no simple way to add a ground. He mentioned a grounding plate as a  
> solution, but he doesn?t particularly recommend it.
> 
> 
>  How have other people addressed this?
> 
> 
>  Thanks.
> 
>  Dan Landrigan
> 
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