On board in a thunderstorm

jlsparks

New member
As a new C-Dory owner and looking forward to overnight camping, Any suggestion on where is the best area to move to in the event of an overnigt thunderboomer? Close to shore, or stay anchored out in the bay?

Jim & Julie
 
Having been hit with all kinds of stuff in the middle of the night, my suggestion is to always anchor in as bomb-proof a place as you can. This is a lesson I'm still trying to learn myself. But it is amazing the stuff that can brew up and having to move in the middle of the night in a thunderstorm(which I've done!) is an unhappy experience. Also, if there's a chance of lightning, put your VHF antenna down before you retire; they're magnets.
Al
 
Thanks for the info, Were looking forward to many happy nights enjoying the eveings. I thought if the weather was brewing and it looked like a storm, one could pull the boat out if that's available but I would not always have that option handy.

Thanks
 
I'm not a sailor, but I am fairly certain that sailor's have a contingency for thunderstorms while on the water... I am not sure of the specs, but there is a "grounding" circuit available for the mast. Perhaps a sailor would have more info... Whether it could be conformed to a C-Dory I really don't know.

Craig
 
The idea for sailors is to connect jumper cable to a shroud and toss the other end in the water. Our last boat had a copper strip that went down the daggerboard trunk to dissapate the lightning... at least that is the plan.

In reality (and I think most sailors will go with me on this), anchor or get near a boat with a TALLER mast! :wink Yes, really. Also, I would much rather be near shore... out on the water, you are the tallest thing around. And if things really go to hell, you are just plain closer to shore. Also, don't touch metal stuff on the boat during a storm (there's a reason for those pretty wood wheels and tillers). HTH

Best wishes,
Jim B.
 
After reading much about lightning, and having been in literally dozens of lightning storms on sailboats, most will agree that there is no clear answer on if grounding a boat helps to avoid lightning strikes.

Before leaving on a two year singlehanded cruise on my Jeanneau Tonic 23, I had it grounded by a marine electrician. This involved running wires from the chainplates (terminal end of the standing ss rigging) to a gold-plated grounding plate attached to the bottom of the hull (outside) just aft of the keel.

Also, my mast was supported by a 4" diameter ss compression post under the deck. This post also was a mounting point for the table and was fiberglassed into the hull on top of the keel (cast iron). Pretty solid ground there, too.

Surprisingly, an article in Practical Sailor years ago studied a survey of sailboats struck by lightning. Half were grounded and half weren't. Go figure.

One old wive's tale of how to ground your boat was to attach jumper cables to the rigging and throw the other end into the water. Somehow the match-up of jumper cables and the power of a lightning bolt is a bit amusing.

Personal experince and opinion. I don't think it makes a difference. Although I have literally, dozens of times, had lightning strike the water within 25 yards of my boat, sporting a masthead 40 feet over the waterline, with the boat being both grounded or ungrounded, I have never been struck. If 40 feet of aluminum mast doesn't get hit, I'm not sure that we have much to worry about.

The radio antenna as an attractor? I don't think so.

I'm sure that the scientific types, which I am defintely not, will chime in here with some good advice and maybe blow holes in my arguments, but lightning has defintely not blown holes in Spirit.

Nick
"Valkyrie"
 
One of the most important things you can ever learn about how to safely operate a boat is to know when to stay home...

Edit: Just had a thought... For anyone wishing to get adventurous and try their hand at adverse conditions... If you've never seen pieces of the shipwrecks on the north shore of Lake Superior... It's enought to make an avid boater take up tiddlewinks... When 1/2" steel bulkheads get twisted like beer cans, it's time to head for home.
 
When I think or know the lightning storm is coming, I go back into a high-walled cove with trees on the ridges above, anchor, and drop all the antennas.

Sailboats have grounding straps from their metal masts to their keel or someting else underwater.

This helps protect the occupants from getting into the path of the elctricity.

Some say that the presence of the ground strap actually makes the boat more of a target, but in the long run, the folks inside are actually safer with it.

Also, a good lightening strike may wipe out most of the electronics on a boat.

Not only could you loose your radios and navigation equipment, but it could also disable the engine, if the ignition system is hit.

I was on a race committee boat that was a sailboat on an 8,500 ft Colorado lake one time when a storm came in*. We couldn't touch the metal shrouds, mast, or outboard motor without getting mildly shocked. Our hair even stood on end! So we went below and opened up a bottle of sherry and soon all was well!

Joe.

* They say in Colorado "If you don't like the weather, wait 15 minutes, it'll be different!" Very true in mountainous areas, and in direct proportion to your altitude!


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An ex long distance sailor who has seen his share of thunderstorms. Yes, chains or cable with a plate are susposed to help disipate any static build up in the boat its self. There is a cone of protection from the mast, which is grounded. I have personally been hit 3 times with minor side lobes of lightning strikes. Never any serious damage (at least my wife doesn't think so)--The only time was on the water on a friend's boat. His idea was to get as close to the sailboat ahead of him--mine was to go below decks. The sailboat had a direct strike and blew out all electrical gear, stopping the diesel engine along the way. There was a small side lobe which hit our bimini top, jumped to my arm and to my wife. Like a minor shock.

One of our long distance boats which had a 60 foot mast and an "ideal" grounding system (3/4" copper tubing, flattened from the base of the mast to a 1 sq foot copper plate in the water just under the mast, and a dissipator on the masthead)--had three direct strikes after I sold the boat.
Lots of damage, blown out thru hulls, fired all electrical etc. One stike came thru the water.

My policy in a boat like the C Dory is to put down all antennas. Get close to shore and anchor if possiable--if I can outrun the storm, I will try (we have them frequently in Florida). I go below, stay below deck away from any metal objects during the storm. I also disconnect all electronics. This includes all antennas, power sources and grounds.

I don't anticipate putting anything different in the new TC 255 than we have in the C Dory22. No specfic lightning ground, although I will have a ham radio ground.
 
The radio antenna as an attractor? I don't think so.
Valkerie is infinitely more experienced than I, but I'd certainly take issue with this quote. It may be consistent with his personal experience (to date), but golf umbrellas have been notoriously effective attractors, with tragic consequences. I can't imagine any antenna being immune from attack.

e.g.
 
The antenna is no where big enough to take the whole lightening bolt, but instead serves as an attraction point as it leaks electrons off into the air, causing the air to become an ionized conductor, and offering a path to the electrical charge above to the ground below.

Joe.
 
There's more to worry about with a thunderstorm at night than lightning. And, as I said, it amazes me what can brew up during the night following an otherwise lovely evening. Last summer we played the odds and anchored in one of our favorite, though somewhat exposed, spots, only to be damn-near blown into the rocks during an unforcasted thunderstorm at 2 AM. It's quite sobering to see waves crashing on the lighning-illuminated shoreline about 20 feet away while being buffeted with violent downbursts of storm-driven air. I'm glad the anchor held.
Al
 
Sea Wolf,

Just as a I thought, a science type came along and debunked my ideas! Now you know why you taught science and I taught English and history.

Nick
"Valkyrie"
 
What Sea Wolf mentioned is an important perspective on prevention.... lightning seem so choose it's target based upon a 'stream' of electrons coming UP from the potential target much PRIOR to the actual strike. As such, even the tiniest conductor can set up a predelective increased probability of being hit.

Worried about all the lightning we get here in Kansas, I have scoured the Internet and other sources for years trying to find some reasonable protective moves. It seems there are alot of cases where those who have put the huge underwater plates and grounding have suffered severe damage including holes blown thru the hulls! With all the thousands of small boats out on the water during storms here in Kansas, the amazing thing is the low number that actually get hit. It does seem from observation that you don't want to beach your boat during a lightning storm in that beached boats were hit more often than boats in the water. Maybe the trees on shore draw strikes nearer to shore?

I have been out on the Gulf of Mexico several times with the rigging glowing with St. Elmo's Fire, and our hair on end, but we never were actually hit...

John
 
More comparisons.... You know that cars are one of the safest places to be in thunderstorms (relating to lightning), but cars are NOT grounded. The lightning jumps from the metal car parts to the ground. As such, I always figured it ought to be able to jump from the chainplates to the water without me trying to guide it intimately close to my hull with a ground plate.

they say that, if you feel the hair on your head or extremities standing on end, you need to let go of anything metal and get as low as possible, without actually lying down on the ground. JOhn
 
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