LIGHTNING DETAILS -Risk Management

[GTom]

Originally Posted by Basil

Hi
As for protection a friend had his super lightening protector unit which he had purchased at the top of his mast, this still remained after he was struck ,but both his outboard motor had gone along with most everything else.

Do you have any information what kind of lightning -scarecrow was it? There is quite a lot of snake oil in tge market advertised even in various topics of this forum.

Originally Posted by thunderhoof

Also, I think a good place to keep your battery operated radio and GPS should be in your sock drawer - literally. Someplace not near wiring, rigging or plumbing. Placing the items in a metalized container could only help.

Faraday cage (can be a copper mesh bag, metal box, whatever. All electronic items you value and not a must, your handheld vhf can fry from the EMP 30' away from the lightning path...

[Basil]

Hi
Sorry I don’t know what type of lightening protector it was , but it certainly did not work.
This thread is missing the point. If you are near or struck by lightening it makes no difference if things have fuse etc or are unplugged. The air is alive with electricity an I know of cases where spare LEDs stored in a dry bilge (not connected) have all found to have been blown.
If there was a proven method of stopping the damage of a lightening strike insurance companies would have been demanding yacht owners fit it.
I have not problem saying a lightening storm scare,s me like nothing else, you just sit there an wait.

[Pelagic]

Originally Posted by puffcard

My boat has been hit twice. The 2nd strike happened just after I finished fixing the last item from the first hit. I just replaced the AM FM radio and turned it on for five minutes to test went home and the boat was struck that night. I've also personally was hit while working on a boat that was sitting on the hard high and dry.

Thanks puffcard for sharing.

That last one sounds like what they call... "Bolt from the blue" lightning type....as described in my first/second post and here.
http://stormhighway.com/types.php

I am not convinced that knowing the types of lightning you are observing, is not useful in managing what precautions you need to take t


This upward moving ground to cloud type is Specific to talk structures.
Does that apply to masts?

http://stormhighway.com/tower.php

[GTom]

Originally Posted by Basil

Hi
Sorry I don’t know what type of lightening protector it was , but it certainly did not work.
This thread is missing the point. If you are near or struck by lightening it makes no difference if things have fuse etc or are unplugged. The air is alive with electricity an I know of cases where spare LEDs stored in a dry bilge (not connected) have all found to have been blown.
If there was a proven method of stopping the damage of a lightening strike insurance companies would have been demanding yacht owners fit it.
I have not problem saying a lightening storm scare,s me like nothing else, you just sit there an wait.

Yupp, that's the EMP. I am shopping for my new boat and a few metal boxes are definitely on the list, but I have to educate myself which ones qualify.

[clownfishsydney]

Originally Posted by Cadence

Out of curiosity, was the rigging bonded. I've always wondered, does it help of invite lightning? I'm sure the are many threads and opinions on this. I have had boats both ways and I think I've just been lucky.

Sorry, no idea what bonded means.

[ottow]

A set of wooden plugs that fits any transducer holes is a good part of a risk management strategy.
There has been several documented instances where a lightning strike has blown out the transducer from the fitting, with obvious results.

[Cadence]

Originally Posted by GTom

There are a few lightning topics already on CF, from those I learnt that there is no real protection against the hit, you can only reduce the damage. E.g. keep valuable not used/backup electronic equipment in a Faraday cage/box. Disconnecting stuff doesn't help, the EMP of a nearby lightning fries a completely isolated handheld VHF/mobile phone too. Actually I can imagine if my neighbor in the marina takes a hit my instruments fry too, without being in the actual lightning path.

Cats, bilge keelers need to pay attention on conduits to ensure the path of lightning to the sea.

Lightning produces one hell of a corona so, as you point out, a direct hit running through the electronics is not necessary. That said I wonder how many bonded boats are using a shielded wire from rigging to grounding plate? Then again what would you wire the shield to ground? Possibly a spark gap to ground? just food for thought.

[Davidhoy]

I'm going to be rebuilding the nav station on my boat, and am thinking of creating a storage area that has a built-in Faraday cage, in the form of a copper foil/mesh lining all the interior surfaces, with appropriate conductive gaskets at the opening. If I keep my ditch bag inside (which contains an EPIRB, spare handheld DSC-VHF, sat-phone, etc.), then hopefully at least those items will be spared the destruction caused by the EMP accompanying a lightning strike. Any thoughts about the viability of this approach?

Of course nothing is guaranteed protection against lightning, it is a truly strange beast...

[ottow]

Hard to know until tested ;-)
But probably a lot better than keeping the bag in a locker.

Mitigation is the way to go, I honestly do not believe one can protect a AWB yacht from lightning.
The bolt jumps 100s of meters in free air before striking, carrying millions of amps. Any protective device smaller than a main battle tank will simply fry...

Bonding wiring (of sufficient gauge) or wires from the stays/rigging to water may protect the hull and provide a better path for most of the energy.

[Lambretta]

Originally Posted by clownfishsydney

Sorry, no idea what bonded means.

And I thought I was the only one
Bonded for me either means glued or someone who has a registered bond on your property

[puffcard]

As an electrical engineer, I have access to Mylar ESD bags that electronics come in. I was using them to put my portable devices in during thunderstorms. But a static discharge and a lightning EMP are two very different events. So I'm going to look into Faraday bays to store devices like the list below. Needs to have about 60dB of attenuation. I'll keep the ESD bags to bag each item.

laptop
tablet
cell phone
handheld gps
solar charger usb
solar light, Luci
LED flashlight, old school ones are ok
handheld radios, (VHF, shortwave radio)
Also thinking of keeping a spare solar controller and voltage regulator in a bag.

If you want to make a cheap Faraday cage, take a metal cooking sheet or bake pan. Preferably not with any non-stick coating. Put your items in it and wrap with aluminum foil.

[ottow]

Originally Posted by Lambretta

And I thought I was the only one
Bonded for me either means glued or someone who has a registered bond on your property

Bonding (in this aspect): http://threesheetsnw.com/files/2012/...protection.jpg
From http://www.threesheetsnw.com/blog/20...g-experts-say/

[Cadence]

Originally Posted by clownfishsydney

Sorry, no idea what bonded means.

In spite of all the wise guys with the glue, it is basically grounding the rigging to an under water conductive surface. ottow illustrated it.

[noelex 77]

Lightning damage is a common problem for cruising boats.

Ensuring a strike has electrical path to ground (water) reduces the chance of significant issues, for example, where a hole is blown in the hull. Not nice .

Many people worry this grounding will increase their chance of a strike, but all the evidence suggests it actually reduces it (because grounding reduces the static charge at the masthead), although the effect is only slight. The yacht should be grounded primarily to reduce the chance of severe damage, not because it reduces the chance of the strike. The brush head static charge dissipators seem to have only a very minor benefit in reducing the chance of a strike over simply grounding the mast.

If you have a moderate or severe strike, all your electronics will be toast, but in a minor strike switching off or disconnecting electronics (preferably with a large air gap) helps. Storing some essential electronics in a Faraday cage is, I think, sensible.

Grounding the mast, having good insurance, and having some essential electronics in a Faraday cage are the most important steps. If you turn off as much electronics as possible when lightening is about, this is also helpful.

Oh, and don’t be watching the movie Titanic when lightning is about (voice of experience ).

[Cadence]

Originally Posted by noelex 77

Lightning damage is a common problem for cruising boats.

Ensuring a strike has electrical path to ground (water) reduces the chance of significant issues, for example, where a hole is blown in the hull. Not nice .

Many people worry this grounding will increase their chance of a strike, but all the evidence suggests it actually reduces it (because grounding reduces the static charge at the masthead), although the effect is only slight. The yacht should be grounded primarily to reduce the chance of severe damage, not because it reduces the chance of the strike. The brush head static charge dissipators seem to have only a very minor benefit in reducing the chance of a strike over simply grounding the mast.

If you have a moderate or severe strike, all your electronics will be toast, but in a minor strike switching off or disconnecting electronics (preferably with a large air gap) helps. Storing some essential electronics in a Faraday cage is, I think, sensible.

Grounding the mast, having good insurance, and having some essential electronics in a Faraday cage are the most important steps. If you turn off as much electronics as possible when lightening is about, this is also helpful.

Oh, and don’t be watching the movie Titanic when lightening is about (voice of experience ).

It's a crap shoot! It would be nice if the answer could be found.