Why do boats need lightning protection, and if so how designed for each vessel? An age old question and as R Trane says much more complicated than a shore based system. To whit:
- Does protection if you are at the marina offer the same protection as compared to cruising and vice versa?
- How about when you are on the hard?
- How about if you are anchored with an all chain vs rope rode?
- How about salt vs fresh water?
- Why worry if you cruise in low lightning areas?
The list is endless and the answers not the same. For sure though, an all electric solar boat cruising in the lightning capital of NA- Florida - could prove interesting if struck
The most authoritative source on lightning statistics in the USA is NOAA
NWS Lightning Safety Resources and Links as a summary in;
2012
http://www.nws.noaa.gov/om/hazstats/light12.pdf there were 28 lightning fatalities, 3 boating 10.7%,
2011
http://www.nws.noaa.gov/om/hazstats/light11.pdf there were 26 lightning fatalities, 0 boating, 0%
2010
http://www.nws.noaa.gov/om/hazstats/light10.pdf there were 29 lightning fatalities, 2 boating, 6.9%
2009
http://www.nws.noaa.gov/om/hazstats/light09.pdf there were 34 lightning fatalities, 2 boating, 5.9%
2008
http://www.nws.noaa.gov/om/hazstats/light08.pdf there were 28 lightning fatalities, 3 boating, 11.1%
2007
http://www.nws.noaa.gov/om/hazstats/light07.pdf there were 45 lightning fatalities, 2 boating, 4.4%
2006
http://www.nws.noaa.gov/om/hazstats/light06.pdf there were 47 lightning fatalities, 2 boating, 4%
So over a 7 year period there were 14 fatalities to people on boats from lightning. The reason that boats need lightning protection is because most of these 14 fatalities could have been prevented with adequate lightning protection. Of all weather related fatalities, lightning fatalities are the easiest to prevent.
Dr. Ewen Thomson is a renowned authority on lightning protection. His web site
Marine Lightning Protection Inc. provides details on how to design and install a lightning protection system (I won't repeat all his information here). They also provide consulting services
Consulting if you don't feel comfortable designing your own lightning protection.
Does protection if you are at the marina offer the same protection as compared to cruising and vice versa? Yes, a properly designed lightning protection system installed on the boat will provide the same level of protection in the marina and cruising.
How about when you are on the hard? When your on the hard the the electrodes should be connected to grounding devices similar to your home lightning protection system.
How about if you are anchored with an all chain vs rope rode? That should not make any difference. When a charge builds up in the clouds and opposite charge is drawn to the surface which created the potential energy that causes the discharge. This is why side flashes occur the maximum potential is between the sky and the surface of the water. The anchor is going to the bottom where the potential is actually lower.
How about salt vs fresh water? Because salt water is a better conductor that fresh water the side flash is less common in salt water than fresh water.
Why worry if you cruise in low lightning areas? If you only cruise in an area with very low lightning strike incidence
http://www.lightningsafety.noaa.gov/stats/NLDN_CG_Flash_Density_Miles_1997-2012.png then you can go back to burring your head in the sand.
The list of answers is just an long as the list of questions.
Everyone knows the potential for a lightning strike exists, that is pretty much a given. No one is pretending it does not exist so strike that statement please.
Well that is a start. I was referring to builders that choose to pretend that the risk of a lightning strike does not exist. I think that if you asked most boat buyers they assume that boats are equipped with lightning protection.
If you can describe the "best lightning protection available" you might become a prizewinning fiction writer or a multi-millionaire. Best for what kind of boat where in what atmospheric and environmental conditions? Just making the statement that the boat is built with "lightning protection" implies that it is "protected" to some degree and if it ever got hit by lightning the manufacturer would be stuck with a bill for every new electronic device on the market at the time. Heaven forbid anyone got hurt.
What degree of "protection" do you propose? How would you measure the level at which it failed to "protect" vs what level of "protection" is provided by the "best lightning protection available?"
Once you have read Dr. Ewen Thomson web site
Marine Lightning Protection Inc. I think the majority of your questions will be answered. When I first started my career in the aerospace business I was a rocket propulsion expert. One of my jobs was to assure that the launch facility meet the companies safety requirements. I significant part of this involved evaluating the lightning protection system at the launch pad to assure that the rocket, missile or launch vehicle was not struck by lightning. The principals that were used on launch pads were identical to what Dr. Ewen Thomson proposes except the grounding rods that were driven into the ground are replaces by electrodes at the waterline.
This isn't black magic that nobody understands. This is application of scientific principals that have been known and understood for over 100 years.