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Old 05-10-2009, 20:25   #1
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Really ? No Lightning Protection ?

that works... does anyone have their electronics on a "plug n play" setup where you could easily unplug them from everything, perhaps hide them in the boat when you are gone.. something so easy you could do it in 15min....pull them out and put them back in... everthing from radar, chart plotters, SSBs, VHF etc... Insurance has me bummed out and I am thinking this is really the biggest exposure (except for sinking )

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Old 08-10-2009, 21:12   #2
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Not really, most of the instruments are buried in the walls of the boat or below decks with only the "readouts" up at the helm station. The more things you can recess into the bulkheads or mount on the bulkheads so that they are thru-bolted reduces the likelihood that anybody could steal them. And then they only get the repeater instruments and not the computer boxes that are mounted inside the vessel. Portable GPS's and stuff can be slipped out of their holders and stored below.
- - You can engineer disconnects for the cabling so that you can unmount and store below free standing systems but that is a lot of work. Normally if the systems are bolted into the structure of the boat quickly getting them off the boat is not possible.
- - If storing the boat for a long time where you cannot check on it then dismounting displays becomes practical but normally just find a storage boatyard with a "secure" section is a lot easier.
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Old 14-10-2009, 09:33   #3
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You might consider making it easy to disconnect your VHF and SSB antennas from your radios. These are the things that are most likely to sustain damage from a nearby strike, which is much more likely than a direct strike. With a direct strike, there may be nothing that will with certainty protect your equipment short of pulling it and putting it in your Faraday cage (i.e. oven). Anything you can do to remove your equipment from likely conduction paths will improve your odds, however. You can also put "lightning arrestors", like from Polyphaser, on your antenna leads, and even other signal and power leads for more protection. Again, these may not protect in a direct strike, but could save you lots of money with a nearby strike. It just depends on how much effort you want to put into it.
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Old 15-10-2009, 07:21   #4
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Very common, my boat was hit, my dads boat was hit. Could be as minor as a damaged VHF or blow 60 holes in the bottom as that surge go's to ground. Insurance is best, install one of those mast head chimney brushes ( they do work ). Most equipment is damaged from the surge through grounding (the back door ).
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Old 15-10-2009, 09:29   #5
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My radar control head , GPS, depth sounder and laptop all go home with me in the computer bag. No problems with thieves or lightning. This seems to work well for me but probably wouldn't with a larger or more complicated setup. Lightning doesn't seem to be an issue in the PNW, and the "bottle brushes" aren't seen atop masts as much other areas and it rarely comes up in conversation. I have no idea why.
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Old 23-01-2012, 07:49   #6
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Re: Really? No Lightning Protection?

With smaller boats with limited (or basic) instrumentation removing the items when you head home is a very good idea. Even for mid sized sailing boats it might work.

But then you get the full time cruising boats and all that stuff is bolted into the gizzards of the boat. And it is all connected together with a rat's nest of wires and cables and connectors. And a big potential problem with introducing more disconnects is corrosion. Each connector is exposed to the salt air environment and the contacts/pins/connectors will corrode and you will lose the signal strength necessary for operation.

I have seen boats that have been "stripped" by thieves, etc., and usually they simply use bolt cutters and wire cutters. The wiring to the unit is chopped off and the base unit removed. If you prowl the used boat parts stores you will radar units where the cabling was hacked/cut off.
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Old 23-01-2012, 08:25   #7
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Re: Really? No Lightning Protection?

But you still won't be immune. We had a direct strike with no reason to believe it would happen. No previous lightning activity and none after the strike either. Just an overcast day without big thunderheads and BOOM - then smoke. It simply would not be practical to unplug and hide everything whenever it is not used, let alone what would you do if under sail?

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Old 23-01-2012, 08:57   #8
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Re: Really? No Lightning Protection?

Which is why, personally, I don't think there is any practical thing as "Lightning Protection." What I do think is possible and practical is "Lightning mitigation" or minimalizing the damage done by a lightning strike. Static dissipators and good grounding paths from mast to ocean is about all you can do when underway.
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Old 23-01-2012, 09:08   #9
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Re: Really? No Lightning Protection?

There are plenty of stories on here of handhelds in the ditchbag, with their batteries disconnected, getting fried from a lightning strike. You can mitigate it as best as possible but there's no way to ensure success. It's lightning.
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Old 23-01-2012, 09:20   #10
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Re: Really? No Lightning Protection?

The magnetic fields around a lightning strike are so intense that even the runs of wiring on a circuit board are long enough for damaging currents to be induced. If you want to protect your ditch bag equipment, probably including batteries it all needs to be in a steel container, not aluminum or stainless, that completely encases the items. A small cash box would do the trick for a ditchbag. For a very close or direct strike, luck becomes a factor too.
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Old 28-01-2012, 20:45   #11
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Re: Really? No Lightning Protection?

Perhaps off topic, but would any of you buy a boat that has a history of being struck by lightening ?

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Old 28-01-2012, 20:59   #12
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Re: Really? No Lightning Protection?

If there was no unfixed or improperly fixed structural damage (get a surveyor and tell him it was struck by lightning), then no problem at all.

If by "a history of being struck by lightning" means that it regularly gets hit once a week or so, I wouldn't go close enough to it to make a decision.

Of course, we own a boat struck by lightning...

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Old 28-01-2012, 21:20   #13
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Re: Really? No Lightning Protection?

Quote:
Originally Posted by Adelie View Post
The magnetic fields around a lightning strike are so intense that even the runs of wiring on a circuit board are long enough for damaging currents to be induced. If you want to protect your ditch bag equipment, probably including batteries it all needs to be in a steel container, not aluminum or stainless, that completely encases the items. A small cash box would do the trick for a ditchbag. For a very close or direct strike, luck becomes a factor too.
(Red strike-through my formatting).

ANY metal box or cage should do, so long as it is a good conductor. Google the phrase "Faraday cage".
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Old 29-01-2012, 08:50   #14
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Re: Really ? No Lightning Protection ?

Question, would grounding the mast, or onboard wireing through an anchor chain to a set anchor make a difference in giving a strike a path off the boat?
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Old 29-01-2012, 15:08   #15
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Re: Really? No Lightning Protection?

Quote:
Originally Posted by SailFastTri View Post
(Red strike-through my formatting).

ANY metal box or cage should do, so long as it is a good conductor. Google the phrase "Faraday cage".
Point taken up to a point. Any metal box will do the job for electrical currents but my understanding WAS they won't do it for magnetic fields.

Faraday cage - Wikipedia, the free encyclopedia

I researched this a bit more and found supporting evidence for my belief but nothing really definitive. The most definitive things I found were that there are shielding manufacturers that specialize in shielding for magnetic fields and a site that discussed military watches immediately after WWII where the movement was encased in soft iron to prevent magnetic effects.

Jaeger-LeCoultre Mark 11 Tracking Page
Is there a faraday cage for magnetic fields besides a superconductor? | Answerbag
Electrical Engineering: Faraday Cage/Ice pail effect, magnetic field strength, hollow sphere
Microwave & electromagnetic engineering - Is this a Faraday cage?

Ultimately I came back around to Wikipedia again and found this:
Electromagnetic shielding - Wikipedia, the free encyclopedia.

What I ultimately have taken away from all of this is that a Faraday cage of any metal will provide some protection against high frequency magnetic fields of weak to modest strength.

For low frequency or very strong fields a ferromagnetic (iron or a relative of iron) metal is better, the more permeable the better, and multiple layers improve performance too.

You can argue about the frequency of the magnetic field in a lightning strike but most would agree the magnetic field is going to be pretty strong in keeping with the very high electrical field.

In the interest of cost vs performance, I would go with a small steel cash box inside a larger one.
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