Copper Coat as faraday cage ?

If lightning is around disconnect the VHF from the aerial and take it off it's mounting plus any other electrical equipment up the mast or outside the boat. Disconnect CD/DVD player FM/AM radio and anything else and take it off it's mounting and then put everything in the oven, also the handheld GPS. That's what we did, don't turn the oven on ;-)
 
KellysEye said:
If lightning is around disconnect the VHF from the aerial and take it off it's mounting plus any other electrical equipment up the mast or outside the boat. Disconnect CD/DVD player FM/AM radio and anything else and take it off it's mounting and then put everything in the oven, also the handheld GPS. That's what we did, don't turn the oven on ;-)
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Did everything still work after the strike?
 
rob2 said:
Giving it some more thought, particularly as you were originally interested in whether protection was offered from acharge coming in from a nearby sea strike rather than a downward air strike. High voltage discharges tend to flow across surfaces rather than through a conductor, in fact a wet hull is attributed to be instrumental in the conversion of a strike into St Elmos fire within the vessel. Not sure how all this fits together, but I suspect that any wet surface would react much the same above a critical voltage.

Rob.
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Veering off at a tangent, HV burns(including lightning) can manifest themselves as fern or feather shapes on the skin, as the energy travels along the skin rather through flesh and bone.
 
AntarcticPilot said:
Actually, even if it were conductive - which it isn't - it wouldn't make a Faraday cage. A Faraday cage is a complete enclosure, with no holes larger than the longest wavelength it is to block. The Coppercoat - or copper sheathing or whatever - on a hull has a dirty great hole in the top!
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I tend to agree, I see little point in having an underwater Faraday cage. Certainly copper granules set in resin will not act as one. Even if it did the heat generated would write-off the hull and probably set the yacht on fire. You would need some sort of grid of wire mesh to have any real effect.

A further thought is the power involved in a lightening strike. I've seen lead sheathed cable vaporised by lightning strike, together with the copper conductors inside it. I suspect that even a wire mesh "cage" on the hull would do considerable damage to the hull anyway were it to be struck.

How long wire mesh would last under sea water is questionable too - as is how it would react with other metal through-hull fittings.

Life is full of risk, the probability of damage from lightening is very very low. Its a risk best managed by insurance, make sure your policy covers it and stop worrying about it.

In any case, if you take a solid hit by lightening it'll probably kill you - so you've nothing to worry about anyway
 
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Interesting that modern jet aircaft often get lightning strike. I heard a claim once that averages once per year. Though they flyat an altitude above storms and use weather radar to avoid storrms they still often descend/ascend through storms to land or take off. The typical strike is from tip of tail or wing tip to nose or other wing. Obviously cloud to cloud strikes. The huge amount of low resistance aluminium means that a lot of current can flow with little harm. Carbon fibre or GRP extremity parts always have copper or alim mesh near the surface to reduce resistance. The typical damage is a small burn mark at entry and exit. Of course all systems are checked after a strike and the mafnetic compass is checked for errors or change of errors due to possible magnetisation of ferrous parts by high current.
In the context of this argument you might describe the fuselage as a Faraday cage though I would rather describe it as a current conductor. good luck olewill
 
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