what procedures should be followed when lightening is eminent

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benlui

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If a lightening storm is passing, what procedures should i take to make my boat and crew as safe as possible and less vunerable to a strike? Is there anything other than praying to god it doesn’t strike my mast or any other part of the boat?
Ie, not standing on deck, getting sails down, shutting down electrical equip etc, is there like a checklist for this?
Had a scare several months back when a lightening storm was passing over us and i wouldn’t leave a crew member on deck to get the main down even dough the wind was blowing 55kts for ten minutes and we had no reef in. It came out of nowhere and caught us by surprise but i felt it was better to run with the wind and let the main blow out rather than rick the crew member getting struck by lightening. Fortunately the sail and rigging withstood the blow and no strike caught us but for future ref im wondering what procedure to follow if you know lightening is about.
 
unplug any cables from equipment u can, e.g. vhf and chartplotter aerials and power cables (presuming they are readily unplagable). Put handheld gps and vhf in oven (presuming its not on of course).

I have seen bad damage to skin fitting where lightening went thru bonding and earthed to see via the thru hulls. I suppose u could turn of sea cocks just incase.

Oh and check your insurance is in date ;-)

Ants
 
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what procedures should be followed when lightening is eminent

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Insure your bote is probably grounded or rusk elocution at see.
 
There is not much doubt that the mast (Al) will be hit if any hit at all.
I think it most important to provide the lowest resistance connection mast to sea. (Not via stays)

If that is not done (or even if it is) priority is to disconnect VHF antenna and any other antenna that is on the mast. Then all other plugs out of radios /electronics.

I think you were over anxious about pulling down the main sail ie not much safer in the cabin. Just don't touch any wiring or metal parts.

good luck olewill
 
For lightening just use darker sun glasses /forums/images/graemlins/ooo.gif.
Lightning: Ion dissipator brush on mast top
Proper grounding mast to keel or grounding plate.
Disconnect instruments and com's.
Store portable devises in the stove.
Pray
 
earthing you mast will not reduce the risk of being hit but may reduce damage done if you are. However do disconnect every cable as the hall effect can create very high voltage surges - I have known old fashioned filament bulbs to light up and a friend got a nasty shock froma piece of cable just waiting to be connected. any portable electronics should be placed in a metal box (closed) better off as far from mast as possible!!
 
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earthing you mast will not reduce the risk of being hit but may reduce damage done if you are. However do disconnect every cable as the hall effect can create very high voltage surges - I have known old fashioned filament bulbs to light up and a friend got a nasty shock froma piece of cable just waiting to be connected. any portable electronics should be placed in a metal box (closed) better off as far from mast as possible!!

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I read somewhere that it in fact increases the risk of being hit, but lessens the damage. Also if you have a deck stepped mast which is not earthed at all (meaning no electric wires and also no metal connection to the keel bolts and also the chainplates not connected in any way to the keel or water) you in fact have a farraday's cage. It is really important that there really is no electrical connection from the mast or rigging to the water, engine, keel or electric panels, battery or whatever...
 
Jenku, I'd take what you read with a very large dose of saltwater. Given that in an electrical storm, there's a high likelihood that everything is going to be streaming wet, it's not going to be possible to isolate the mast and rigging. Even if it were, if lightning hit it, with no path to earth, the lightning will create its own path, and end up blowing holes in the boat.


The idea of earthing the mast is not to create a safe path for lighting to follow, but to let any pre-strike static charge leak way into the surrounding sea, so that the mast becomes electrically no more attractive as a target than its surroundings. A lightning conductor is badly named, it should be called a strike preventer.
 
Anchor chain twice round mast and loops into the sea is the best advice. Once in S Brittany my boat was buzzing and all the instruments going offline. The chain trick stopped all this immediately. Of course it is impossible to say what would have happened if I had done nothing. However, my understanding is that a strongly charged thundercloud induces an opposite charge on sticky-up conductors, so increasing the chance of a discharge between the two. Hence lightning conductors on tall buildings, which probably increase the risk of a strike but provide a high-conductance pathway to ground so reducing structural damage.
 
My Bav has a very heavy copper lead from the base of the mast to a keel bolt. Not an expensive precaution for you to take.

Remember that the mast creates a cone of protection in an electrical storm.

Having said that, and doing what others have recommended by way of disconnecting electrical apparatus, the likelihood of being hit is quite small. It seems counter- intuitive to be the only vessel for miles, the storm overhead, the flashes hitting the sea around you, and yet it is the general experience, and mine too.

Press on, I say, what other practical course of action is there?

PWG
 
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My Bav has a very heavy copper lead from the base of the mast to a keel bolt. Not an expensive precaution for you to take.




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I had heard that grounding internally could lead to the charge blowing a hole in the bottom of your boat! Yes it did conduct the charge away but....... Glug Glug Glug
 
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The idea of earthing the mast is not to create a safe path for lighting to follow, but to let any pre-strike static charge leak way into the surrounding sea, so that the mast becomes electrically no more attractive as a target than its surroundings. A lightning conductor is badly named, it should be called a strike preventer.

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Not really true.
A lightning conductor protects a build by creating a safe path.
The key to it is the point at the top, which due to its small radius creates a high field strength for a given potential difference. The air around it is therefore first to ionise, becoming conductive to the lightning.
It's true that it will prevent major strikes, because by flashing over at a lower voltage, the build up of charge is limited compared to the voltage that is required to flash to say a tree.
 
Confused. This is an interesting thread, but I can't really draw any conclusion from what's been said. Surely there must be a simple, definitive and correct way to deal with this situation. What IS the right thing to do if you are out in the sea, miles from anywhere and there is lightning storm head your way?
 
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