[Rhodes22-list] lightning protection
Todd Tavares
sprocket80@mail.com
Tue, 19 Nov 2002 22:08:50 -0500
Brad,
You seem to have done quite a bit of reading on the subject lately. And Rik had a good point, in that, since this is not a clear science that can be defined or tested in a lab, all we really have to go on is statistics. Have you or anyone else found a web site or article that compiled sail boat lightning strike data according to boat size, mast height, strike protection method, or water type?
Todd
----- Original Message -----
From: "Rik Sandberg" <racerrik@rea-alp.com>
Date: Tue, 19 Nov 2002 16:36:07 -0600
To: "The Rhodes 22 mail list" <rhodes22-list@rhodes22.org>
Subject: Re: [Rhodes22-list] lightning protection
> Brad, Todd, Bill
>
> I have to agree with Brad on this point. He said this or she said that,
> really doesn't mean much unless it's backed up with some facts or proof of
> some kind.
>
> Lord knows, I mean no disrespect to the folks who have voiced an opinion on
> this subject. But, in this case, we are dealing with such a powerful
> phenomenon, that testing and proving any theory is virtually impossible with
> the technology available to us now. So, I don't believe that it is possible
> to make a decision, based on the facts when talking about lightning. We
> don't have facts, just theories and statistical musings and I'd bet that
> we'll all be too darned old to sail by the time anyone figures it out for
> sure.
>
> While we do know that boats do get damaged by lightning fairly frequently,
> we can take comfort in the fact that very few of these incidents result in
> an injury, let alone a death.
>
> So, in the end, we can argue this back and forth just like we have in the
> past and when we're done, we'll still know just as much as we did the last
> time this came up; Nothing. There just isn't any conclusive proof that any
> particular way of taking care of this problem is any better than another
> way, or that either of those is much better than doing nothing at all.
>
> I think the best any of us can do with this is go with what feels like the
> best solution to us and know that there is probably as much chance that
> we're wrong as the next guy who does just the opposite.
>
> My personal choice is to not worry about it. :-)
>
> Rik
>
> ----- Original Message -----
> From: "brad haslett" <flybrad@yahoo.com>
> To: "The Rhodes 22 mail list" <rhodes22-list@rhodes22.org>
> Sent: Tuesday, November 19, 2002 3:11 PM
> Subject: Re: [Rhodes22-list] lightning protection
>
>
> > Ladies and Gentlemen:
> >
> > This discussion reminds me of being a fifteen year old
> > kid, apprentice aircraft mechanic, milling around the
> > hangar and listening to the "old guys" tell their "war
> > stories". The scientific facts say that lightning
> > strikes on sailboats is a real threat. How big a
> > threat it is to you is a function of where you sail,
> > how often you sail, and how much time you spend "on
> > the hook". We all have to live with the American
> > jurisprudence system based on precedent but just
> > because someone said something some time ago on the
> > Rhodes list doesn't make it gospel. Todd has a valid
> > point and I challenge anyone to "shoot it down" with
> > evidence, not emotion.
> >
> > Brad Haslett
> > "CoraShen"
> > --- Todd Tavares <sprocket80@mail.com> wrote:
> > >
> > > Thanks Bill,
> > >
> > > My only point was that lightning would
> > > find the shortest and
> > > probably straightest path to the water. My
> > > terminology wasn't
> > > correct. I thought you were implying that
> > > because of the construction
> > > of the R22 that we were less likely to be hit
> > > because of the distance
> > > between the mast and water, and materials in the
> > > boat.
> > >
> > > I have never been on a boat that has been
> > > hit by lightening, but
> > > have seen many ground strikes close up. My only
> > > hope would be to
> > > survive (including making it back or being
> > > rescued from a partially
> > > submerged boat). Boat and electronics can be
> > > replaced.
> > >
> > > Thanks for the posts.
> > >
> > > Todd
> > >
> > > ----- Original Message -----
> > > From: "Bill Effros"
> > > Date: Tue, 19 Nov 2002 12:52:34 -0500
> > > To: "The Rhodes 22 mail list"
> > > Subject: Re: [Rhodes22-list] lightning protection
> > > > Todd,
> > > >
> > > > The image of lightning "jumping gaps" is
> > > somewhat misleading. Rather
> > > than
> > > > rehash everything that has been said
> > > previously, let me post a few
> > > of the
> > > > responses that meant the most to me from
> > > previous discussions:
> > > >
> > > > Here is how Razz put it:
> > > >
> > > > Rummy,
> > > >
> > > > If your electrical thrills are the result of
> > > electrostatic charge
> > > > building up, grounding the rigging won't
> > > eliminate the problem as it
> > > > is already acting as ground. The charge most
> > > likely is building up
> > > on
> > > > your butt as you slide across the seats. Much
> > > like crossing a wool
> > > > carpet and getting shocked when you touch the
> > > door knob.
> > > >
> > > > Proper grounding for lightning protection
> > > involves installing a
> > > > lightning rod at the top of the mast and
> > > grounding that to a metal
> > > > surface of significant area below the water.
> > > Boats with exposed lead
> > > > or iron keels can use the keel as a grounding
> > > surface. Reuel Parker
> > > > uses a
> > > > 2'x2' copper plate laminated into the bottom of
> > > his centerboard boat
> > > > designs. The cable connecting the lightning rod
> > > to the ground plate
> > > > should be very heavy guage and insulated
> > > > from the mast and rigging. No other metal on
> > > the boat, nor any part
> > > of
> > > > your electrical system should be grounded to
> > > this lightning
> > > protection
> > > > system. The theory is to provide a
> > > > clear alternate path to ground for any
> > > potential charge buildup.
> > > This
> > > > does not attract lightning as it serves to
> > > dissipate most charges
> > > > before they build up to dangerous levels. If a
> > > strike occurs, the
> > > > lightning ground provides a cone of protection
> > > for the boat and its
> > > > occupants equal to the height of the mast. So
> > > as long as you aren't
> > > > touching metal you are not likely to be
> > > injured. One of Parker's 50'
> > > > centerboard schooners took a direct hit that
> > > blew a hole in the hull
> > > > where his ground plate was attached, but no one
> > > on board was injured
> > > > and the boat did not sink as his designs have
> > > water tight bulkheads
> > > > between compartments.
> > > >
> > > > Very few lightning strikes actually occur on
> > > inland lakes or on any
> > > > body of water where land is nearby. Despite the
> > > fact that the
> > > earth's
> > > > surface is 2/3rds water, 94% of all cloud to
> > > earth lightning strikes
> > > > occur on land. This is due to the fact that
> > > large bodies of water
> > > > usually carry a positive ionic charge which is
> > > the same polarity as
> > > > the positive charge build up in thunderstorms
> > > and therefore do not
> > > > represent a good ground potential compared to
> > > the negative charge of
> > > > land surfaces. Earth ground really does mean
> > > solid ground. A boat is
> > > > more likely to be struck sitting in the marina
> > > or anchored near land
> > > > than out sailing and then only if it is the
> > > tallest object around.
> > > >
> > > > RAZZ
> > > >
> > > >
> > > > Here is what Fred Lange had to say:
> > > >
> > > > West Marine will send you a free packet of
> > > articles about lightning.
> > > >
> > > > Included in the material are some interesting
> > > statistical studies
> > > about
> > > > how lightning damages boats. In summary,
> > > sailboats are more likely
> > > to
> > > > be hit than power boats. Boats near shore or
> > > docked are more likely
> > > to
> > > > be hit than boats on the open water. Boats on
> > > salt water are more
> > > > likely to be hit than boats on fresh water.
> > > >
> > > > The physics of it is that if your boat is in a
> > > lower voltage area
> > > > between sky and earth surface, the likelihood
> > > of getting struck is
> > > > higher.
> > > >
> > > > Boats with lightning protection on open salt
> > > water suffer only
> > > slightly
> > > > less damage from lightning strikes than boats
> > > without lightning
> > > > protection, but the people aboard fare better.
> > > Boats on open fresh
> > > > water pretty much always get sunk when they are
> > > hit, but here again
> > > > lightning protection helps the people.
> > > >
> > > > I had a sailboat boat hit at the dock in
> > > brackish water. I know
> > > because
> > > > I had an anchor chain shackled to a stay and
> > > the fiberglass next to
> > > the
> > > > chain was charred. No other damage.
> > > >
> > > > Since I'm mainly a fresh water sailor, I have
> > > extended my experience
> > > > with the chain to try and protect the people in
> > > the boat if I get
> > > hit.
> > > > I have 5 battery cables for clamping to the two
> > > back stays, the fore
> > > > stay and to the port and starboard sides of the
> > > mast. I hope the
> > > cables
> > > > with their frayed ends will ground most of the
> > > strike into the water
> > > > leaving the crew untouched. However, I expect
> > > there is till the
> > > > likelihood that much of the strike will jump
> > > from the base of the
> > > mast,
> > > > though the cabin and out of the bottom of the
> > > hull, filling the
> > > Rhodes
> > > > with water.
> > > >
> > > > Fred
> > > >
> > > > Here is Roger's 2 cents worth:
> > > >
> > > > Thena,
> > > >
> > > > Yes, the Beneteau 40 footer had one of the
> > > tallest masts in the
> > > marina that
> > > > night. But, it wasn't the biggest sailboat &
> > > there
> > === message truncated ===
> >
> >
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>
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