Lightning rules

[david_e]

With lightning forecast for the week-end - what are the general safety rules when lightning is about for;

1 Sailing
2 Motoring/motorsailing
3 At berth in the marina
4 At anchor

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[Juggler7823]

In reality, there is absolutely nothing that you can do except you are not in the wrong place at the wrong time.

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[Sybarite]

I keep a chain shackled to the shrouds which I let into the water in times of lightning. I don't know how effective it is but at least I feel as if I have done something.

John

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[tony_brighton]

Try not to hang onto anything metallic.

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[Rob_Webb]

And say after me.....

"Our father......"

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[jimi]

switch all the electrics off and put whatever hand held stuff you've got(gps vhf etc) in the oven .. assuming the oven is'nt on cos if it is it might get roasted rather than fried!

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[AJW]

Get close to someone with a taller mast that you? But not too close /forums/images/icons/smile.gif

Interesting question though. Last week sat through a thunderstorm on board two identical 38ft yachts rafted together on one anchor and two kedges. Much debate between the two crews as to who was the most vunerable and what we could do about it. Decided that nothing other than having another beer!

AJ

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[ecudc]

I suggest that in a marina or at anchor you head for the nearest pub or your car (before it arrives) and sit it out. Don't leave the boat if the lightening is already close as you could become a target.

If you can't leave, the best place to be will be inside the boat as otherwise if your mast is struck it could leap to you or conduct through any water on the boat so take shelter/anchor if you can or switch on the autopilot and pray.

Electrics in the oven should work as it would create a faraday? Cage, which any encroaching lightening shouldn’t penetrate. I suspect that if hit all your other electrics will be shot to pieces but switching them off may stop fires.


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[vyv_cox]

See last month's YM for an article about this. Every electronic and electric item on board was ruined, including the alternator, except for some spare stuff, GPS and hand held, from memory, that was put in the oven.

I knew some people whose boat was struck in the Intracoastal waterway. Their experience was the same but all of their electric wiring went too. They had supposedly full protection including earthing plates to a keel-stepped mast. Didn't do anything for them.

I like to hope that not earthing the mast is a safer option. But in the end "lightning rules' is an oxymoron. There are no rules with such an unpredictable force.

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[Paul_H]

Go here www.cdc.gov/nasd/ and search on “lightning” for info.



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[alant]

Turn the gas off

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[Oldhand]

Make sure you on board a sailing vessel with metal rigging as the mast and rigging act as a Farady cage, you are thus safer than being out in the open but inside a car is probably safer. As per USCG requirements all structural metal fittings should be electrically bonded to the largest metallic object which is totally immersed, the keel in most cases. Stay down below and be prepared to try and plug a hole in the bottom of the boat should a lightning strike not take a "preferred" route to ground. One example was that a strike favoured the echo sounder wiring and transducer as the route to ground and blew the transducer out of the hull - the boat sank. Avoid touching metallic structure in the boat. Your electronics are just as likely to be destroyed when switched off as they are when switched on due to EMP, unless they were designed for the nuclear war theatre.

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[Neraida]

Fab answer!
I also believe that, if your boat has a strap to a keelbolt, that when you get to port, you should have the bolt(s) checked/replaced, along with the whole rig.

Vessels I have sailed on have been struck on numerous occasions, and I have seen the damage that can occur even to large commercial vessels. Chunks blown out of the foremast and cranes, usually on rusty bits.
We all know that lightning can pop your seacocks and transducers, so, as you said, be ready. Softwood plugs and some bits of timber, plywood, cushions/pillows and a mallet is all you really need. Its also good to have a plan/drill as to what you would do with regards to damage control, not just for lightening, but for all other catastrophies.

Not trying to be patronising, but I am suprised at the amount of times this question comes up in the forum and in mags. If you believed all you read you'd be too scared to venture out of the marina. Lightning, containers, dead welsh people covered in barnacles under the surface, ships running you down in the TSS, lobby pots, gas leaks etc etc etc etc.

IMHO planning is the best action you can take.

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[MainlySteam]

That was a fab answer in answer to a fab answer.

Have heard it claimed, and think it may be pretty well right, that people overestimate their chances of being hit through having a mast. The concept went along the lines that if you imagine the mast providing a cone of protection for the spot of sea the boat sits on (cone tip at top of mast), then the area of the bottom of the cone at sea level is actually very small in comparison to all the sea around. So, to be struck, the lightning was pretty much going to have had to hit very close even if there was no mast - the chances of a hit are therefore only slightly higher with a mast than no mast at all, unless the mast is very tall.

Like most such things, I am not going to try and test it.

John

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[david_e]

Thanks to all, looks like the BBC have cancelled the lightning this week-end so hopefully won't be affected.

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[Twister_Ken]

BBC cancels lightning

So if I'm listening to R4 I should be safe?

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[clouty]

Don't just switch off, unplug.

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[david_e]

Without prejudice

Perfectly safe milud, but only if you are in PW, methinks the solent is going to suffer 'strike & awe' type storms this week-end)

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[oldharry]

I do not beleive that metal rigging on the boat is going to create a sufficient Faraday cage effect to make any difference to the safety or otherwise of the crew. Lightning wll strike where lightning will strke, and the power behind a full discharge will cause major problems on a boat.

Accounts from those who have survived a strike while on their boats, suggest a) keep well clear of metallic objects as they can give a hefty shock even if not involved. b) electrics are likely to be fried regardless - even those that are 'Nuke-proofed' - the only recourse being to disconnect everything and put it in the oven or a large biscuit tin (Farady cage effect does work here) c) be ready for any metal fitting in the hull to be blown out d) be ready to tackle a possibly quite serious fire.

As to Lightning Protection, it seems on balance there is no such thing. The 'Lightning Conductor' attached to large buildings etc is just that - it attracts ligtning, then gives it an easy route to earth without causing structural damage. At least in theory.

Arguably an earthed mast will actually attract a ligthning bolt - the very thing we seek to avoid! Consider what happens in a strike: as the electrical charges increase beteen cloud and earth prior to a lightning discharge, a downward leader from the cloud jumps in a series of steps. As it approaches the ground, corresponding upward leaders rise from various raised objects, until one connects with the down leader and provides a pthe for the main series of discharges - which may in any case jump to another upward leader nearby during the series. This is why pictures sometimes show several streaks of ligthning all originating fro one source in the cloud.

The key seems to be to stop the upward leader from forming, and as this mechanism is not well understood, it is not clear how to do this. However normal electrical physics would suggest that unearthed objects are less likely to form leaders, except that 'normal' physics rules seem not always to apply where lightning is concerned!

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