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evecircleM 06-25-2002 07:11 AM

sailing in a thunderstorm
I would like to know how safe is it to be out in the middle of the bay in a bad lightning storm. Does anyone know? I heard different comments about it. I want the facts, the other day I got caught out there and the lightning came pretty close to me. What could happen if it hits, will it go through the mast down to the keel? Is it grounded somehow? I usually make it back to port in time, but this time I messed up. Slow boat. If anyone has the facts please tell me. I was pretty nervous out there.

Jeff_H 06-25-2002 09:01 AM

sailing in a thunderstorm
The answer to yoru question depends upon how you look at these things. Here on the Chesapeake boats gets struck by lightning quite frequently, both out on the Bay and back at the dock. It happens. On the other hand, there are far more boats on the Bay that never get struck by lightning than do get struck.

When lightning hits a boat it can be quite distructive. It generally will take out the electrical system and anything electronic that is on board. Most grounding systems are not adequate to handle the large current flows of a lightning strike and so there is bound to be some fiberglass damage. In some of the worst cases I have seen a boat riddled with small pinholes and also with a large section of the boat bottom blown away below its keel stepped mast.

When I was a kid, in a thunderstorm, we would rig a heavy copper chain at the stays and upper shrouds that would hang in the water supposedly to conduct the electricity away from the occupied areas of the boat. I never have been convinced that actually works. If you are on board in a thunderstorm try to avoid holding onto metal objects and especially stay away from the mast and shrouds.

One minor point, your does not need to struck directly to have lightning damage or shock you. A boat of mine had what was called induced current damage when lightning struck a tree about a 100 feet way on the bank of the creek. My hand was on a metal tiller and my hand felt numbed for approximately an hour afterward. The depthsounder was ruined.


paulk 06-25-2002 01:32 PM

sailing in a thunderstorm
Like Jeff and common sense suggest, it is safer not to be out in a thunderstorm. If you''re unsure whether your mast is grounded, it might be a good idea to make sure that it is, and done properly. I have heard stories about masts grounded to through-hull fittings, so that when the lightning hits, it blows the fittings out and the boat sinks. Lightning can do wierd things like that; I believe the fittings blew out because the water in them was instantaneously turned to steam, and the fittings or the hoses simply couldn''t take he pressure and heat. Another fun item I read about is how, when your electronic equipment is properly installed, you put a loop in the wire to nullify charges so as to get less interference. Apparently when a million volts comes down the mast and hits the loops, they become like magneto coils, boosting the amperage (?? I''m not a electrician - it boosts something) that fries stuff even more than it would have in the first place. The best idea is to not get hit, and the next best is to be prepared for when you are.

gershel 06-25-2002 02:40 PM

sailing in a thunderstorm
Hi. Has anyone ever heard anything about grounding a catamaran to protect it from a lightning strike?

Jeff_H 06-25-2002 03:04 PM

sailing in a thunderstorm
Yeah, you do it the same as a monohull except that you can''t ground to the keel.

Mama_Cocha 06-26-2002 05:17 AM

sailing in a thunderstorm
I don''t think you can properly ground a cat as lightning will search for the most direct path to ground, which is typically the mast and Keel in a mono, with the cat it would have to move at a 90'' angle at the base of the mast...not going to happen. You can try to ground the shrouds to each hull but you will still have your mast.....If you are caught in a storm move away from mast and shrouds, also put your portable electronics in the oven which will act as a faraday cage and protect them.

Denr 06-26-2002 05:35 AM

sailing in a thunderstorm
Read all about lightning strikes at

Fran49829 06-26-2002 06:58 AM

sailing in a thunderstorm
I listen to the weather reports 4 times a day, watch the sky, always have a lookout, everyone always wears pfds but I am not worrried about being struck by lightning. I have been through hundreds of thunderstorms and am much more worried about searoom and loss of visibility than about lightning. If thousands or even hundreds of sailors were being killed each year from lightning I am sure I would feel different.

MaryBeth 06-27-2002 12:50 AM

sailing in a thunderstorm
Fran, true;

I have been in close storms and cells and hurricanes and more. If you are worried, and are a daysailor, do not go out. What do you do when they tell you not to be close to the binnacle and steering equipment when lightning strikes close by and you are 2,000 miles offshore? Steer with your foot or one finger, as I have done?

Fair winds, and hoping you never get hit,

evecircleM 06-27-2002 08:40 AM

sailing in a thunderstorm
Thanks so much for your reply. I know I won''t be sailing 2,000 miles off shore anytime soon. I do give you alot of credit. I am a daysailor primarily. Thanks again. Eve

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