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Old 04-03-2016, 06:40   #1
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Lightning Strike - EPIRB etc

My wife asked me a question I couldn't answer (ok stop the laughing - my wife asks me lots of questions I can't answer - but here's one for all the gurus)

Assuming the boat is struck by lightning - all electronics in the boat will usually get fried unless they are in a faraday cage (or the oven f.eks).

What about the EPIRB? Ours is mounted on our targa bar. Will it also get fried? Meaning it should be put into the oven if we get caught in a lightning storm?

PLBs? and the like?

carsten
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Old 04-03-2016, 07:32   #2
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Re: Lightning Strike - EPIRB etc

OK, this is opinion, but it may get the discussion started.
I don't buy the "all electronics get fried" Now assuming electronics that are in the path of the discharge, radios that have antennas on the mast and or backstay for example, they get fried due to massive electrical current coming into the antenna, but electronics that are sitting around in the cabin, like a VHF handheld, do they always get fried too? Only thing that would fry them is the EMP of the lightning strike?
Now back in my Army days, we had a lot of electronics that were EMP hardened, so that in the event of a nuclear event, they would still work, it's not all that hard to protect from an EMP.
Aircraft for example that are struck by lightning, almost never suffer any significant electrical damage, they are of course not grounded is likely why, but being in the circuit of the lightning bolt, they are subject to the EMP aren't they?

So do ALL electronics always get fried? Or do electronics that are connected to the ships electrical system, often get fried?
I'd have to think it's unusual for a battery powered electronic device, like a handheld radio, GPS etc to get fried?
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Old 04-03-2016, 07:37   #3
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Re: Lightning Strike - EPIRB etc

A boat got hit in the Baltic some time ago. They tested the EPIRB immediately afterwards and it was kaput. Browse older Segeln issues for the story.

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Old 04-03-2016, 07:49   #4
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Re: Lightning Strike - EPIRB etc

There is a huge magnetic field around the current pulse and that field can induce voltages in any conductive/ semiconductive material inside that field. The magnitude of that induced voltage is dependent on several parameters, but one is the relative geometry between the conductor and the field. So it is possible for an electronic device to survive, but not easy to predict. Put the epirb in the oven is the best policy (you typically know if you are in lightning territory) .
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Old 04-03-2016, 07:54   #5
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Re: Lightning Strike - EPIRB etc

Quote:
Originally Posted by a64pilot View Post

(...) but electronics that are sitting around in the cabin, like a VHF handheld, do they always get fried too?
I have read the following explanation: As the charge passes thru or close to the boat, electric current is induced in all equipment that contains a coil. This current may destroy other components of the equipment.

VHFs, GPSs and EPIRBs may contain coils. The ones I have opened up mostly did. This may change in the new units that are more processor/chipset oriented.

Commonly wiped out by a near strike are: starters, alternators, radioes and all other equipment containing radio functionality (hence GPS and EPIRB too).

There are no hard rules. there seems to be a consistent random element as to what gets obliterated.

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Old 04-03-2016, 08:09   #6
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Re: Lightning Strike - EPIRB etc

You guys are both explaining EMP of course, I'd be a little surprised if something as important as an EPIRB weren't shielded, shielding amounts to being in a metal box, or mesh in the plastic etc.
I doubt you could get a hold of someone who would know, but it would be a good question for the manufacturers

Guess it may add to the possible importance of having more than one EPIRB?
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Old 04-03-2016, 08:26   #7
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pirate Re: Lightning Strike - EPIRB etc

Only thing to pop up with 'lightning resistant' was this


MT403FF 406 MHz EPIRB Float Free Auto-Release

The Global Maritime Distress and Safety System (GMDSS) compliant MT403FF is a 'state of the art'Enclosed satellite distress beacon designed to operate in conjunction with the COSPAS-SARSAT International Satellite Search and Rescue System.

Designed to meet the most demanding regulatory approvals the GME MT403FF is a Class 2, Category 1 EPIRB in a fully enclosed float free housing with a Hammar HRU that will release the beacon at a certain depth, the beacon will then automatically activate.

Using the same innovative technology that produced the MT400 and revolutionised the EPIRB world, the MT403FF now offers commercial vessel operators the same GME performance and value enjoyed by recreational boaters. A key feature of the MT403 series is the use of non-hazardous battery packs that are IATA compliant and allow for restriction free transportation.

The cost of 406 MHz beacon ownership has been dramatically lowered by the introduction of the MT403FF. GME's unique energy conserving microprocessor technology enables the battery replacement period to be extended to 6 years. This technology has significantly reduced both the size and accordingly the replacement price. The MT403FF is factory programmed with a unique serial number which should be registered with the appropriate national Search and Rescue Authority. In many countries, authorities permit the EPIRB to be coded with the vessel's Maritime Mobile Service Identity (MMSI) number or Radio Call Sign. This reprogramming is undertaken by a GME authorised Dealer.

Advantages of a 406 MHz EPIRB over the older analogue EPIRBs include world wide coverage, position location accuracy to within 5 kms, and a more stable transmitted signal resulting in faster response time. Most importantly, the addition of a unique digitally coded message provides Search and Rescue authorities with vital information including the country of beacon registration and identification of the vessel in distress, thus greatly reducing the incidence of false alerts and unneccesary deployment of valuable rescue resources.

An auxiliary homing transmitter is included in the MT403FF to enable suitably equipped Search and Rescue vessels to home in on the distress beacon.

Features
Unrivaled in technology, performance and price.
COSPAS-SARSAT worldwide operation.
Ground breaking microprocessor based design, delivers unparalleled performance and value.
Meets AS/NZ 4280.1:2003 standards. C/S T.001/007. IMO A810 (19).
Zero warm-up digital technology.
Non-hazardous IATA compliant battery pack for restriction free transportation.
High intensity solid state strobe.
Enclosed in a UV resistant float free housing that automatically deploys and activates the EPPIRB when submersed to a depth of 2-4 metres.
Rugged easy-to-mount design.
6 Year battery life.
Easy, in-built self-test with audio / visual alert.
6 Year GME Warranty.

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Old 04-03-2016, 09:42   #8
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Re: Lightning Strike - EPIRB etc

Quote:
Originally Posted by carstenb View Post
My wife asked me a question I couldn't answer (ok stop the laughing - my wife asks me lots of questions I can't answer - but here's one for all the gurus)

Assuming the boat is struck by lightning - all electronics in the boat will usually get fried unless they are in a faraday cage (or the oven f.eks).

What about the EPIRB? Ours is mounted on our targa bar. Will it also get fried? Meaning it should be put into the oven if we get caught in a lightning storm?

PLBs? and the like?

carsten
I have sent an inquiry concerning the matter to the Technical Dept at ACR Electronics and will post the response. FWIW I have seen boats that were hit by lightening, including one two slips away from us in 2008, where not all of the electronics were toasted. If it happened to us, I would definitely want the EPIRB tested to ensure it's working when/if needed.
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Old 04-03-2016, 09:59   #9
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Re: Lightning Strike - EPIRB etc

We were struck by lightning in 1995 - and lost some, not all, of our electronics. The insurance resolved that. As a result we bought one of the Canadian made 'upside down toilet brushes' made of S/S that was meant for electricity poles. We take it from boat to boat - and have not been struck since, despite often having the tallest mast.


Quote:
Originally Posted by svHyLyte View Post
I have sent an inquiry concerning the matter to the Technical Dept at ACR Electronics and will post the response. FWIW I have seen boats that were hit by lightening, including one two slips away from us in 2008, where not all of the electronics were toasted. If it happened to us, I would definitely want the EPIRB tested to ensure it's working when/if needed.
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Old 04-03-2016, 09:59   #10
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Re: Lightning Strike - EPIRB etc

We had a close by strike a few years back. I say close by because none of the three onboard radios were harmed. IP connects one of the backstays to the bonding system as part of a lightning dissipation system. That conductor is a #10 AWG and the insulation had visual distortion because of heat. I had replaced that length of wire a few years earlier and it wasn't like that when I installed it. I had installed an external copper plate below the mast shortly after I purchased the boat for a real lightning dissipation system.

The most logical conclusion is there was enough current induced into that back stay to heat up that #10 copper wire.

Cbreeze was plugged into shore power as well as my 30' Hunter (both in the same receptacle, and both with mast connected copper ground plates). Got the Freedom 10 inverter/charger on the IP and the Radar on the Hunter. No other damage.

Lightning can be pretty fickle mistress.
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Old 04-03-2016, 10:40   #11
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Re: Lightning Strike - EPIRB etc

I was standing in the hanger door in Fliegerhorst Germany watching an unusual thunderstorm, and as I watched an AH-64 go hit. It came in the tail thru the FM radio antenna, splitting so it looked like hair and at the time I assumed it exited thru the chains holding the aircraft to the ground on the tailboom, I was hoping we would be OK as there aren't really any avionics back there.
After the storm we went out to look at the aircraft and noticed that both pitot tube covers had burn holes in the end where apparently the lightning exited there.
I figured the aircraft was toast, but after getting clearance we ran it up and everything electronic worked, but the compass was toast, we got the magetometer out and discovered that every little bit of steel in the aircraft was magnetized.

Lightning does whatever it wants to I guess.

Couple of years ago was sitting in a little restaurant in Carrabelle Fl, and bang, lightning struck a nearby baseball field, hit right at about where the pitchers mound was, did not hit any of the tall light poles surrounding the field, not the tall steel backstop behind home plate?
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Old 04-03-2016, 11:00   #12
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Re: Lightning Strike - EPIRB etc

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OK, this is opinion, but it may get the discussion started.
I don't buy the "all electronics get fried" Now assuming electronics that are in the path of the discharge, radios that have antennas on the mast and or backstay for example, they get fried due to massive electrical current coming into the antenna, but electronics that are sitting around in the cabin, like a VHF handheld, do they always get fried too? Only thing that would fry them is the EMP of the lightning strike?
Now back in my Army days, we had a lot of electronics that were EMP hardened, so that in the event of a nuclear event, they would still work, it's not all that hard to protect from an EMP.
Aircraft for example that are struck by lightning, almost never suffer any significant electrical damage, they are of course not grounded is likely why, but being in the circuit of the lightning bolt, they are subject to the EMP aren't they?

So do ALL electronics always get fried? Or do electronics that are connected to the ships electrical system, often get fried?
I'd have to think it's unusual for a battery powered electronic device, like a handheld radio, GPS etc to get fried?
Yes it is interesting. I've been working on commercial aircraft for 30 years now and we get many, many lightening strikes every year. They almost always cause some damage, static dischargers blown off flight controls/wings, small holes in the fuselage and composite areas, etc but I really don't ever remember any avionics or electrical equipment getting fried. And I really don't think it's because the aircraft parts are built any better. There are numerous non-safety items such a toilet pump motors, entertainment systems etc that I know aren't built any better than the stuff on a boat.

Of course these aircraft are airborne but the lightening still has a an entry and a exit point so it is going through the entire aircraft in some cases. And I would have a hard time really understanding how a boat is "grounded" floating in the water. Maybe since most of the aircraft I work with are primarily metal it helps but there is a quite a bit of composite structure in modern aircraft too. The composite seems to take it just as well the metal in some cases.
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Old 04-03-2016, 11:29   #13
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Re: Lightning Strike - EPIRB etc

I believe pretty much all the composite has a metal mesh in it, sort of making it metal from a lightning perspective, most aircraft of course have to be certified for lightning, little ones and Ag etc. being the one that aren't.
But I had the same questions you have, the aircraft is subjected to the same or similar EMP that a boat is, so why isn't most everything fried?
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Old 04-03-2016, 11:36   #14
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Re: Lightning Strike - EPIRB etc

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I believe pretty much all the composite has a metal mesh in it, sort of making it metal from a lightning perspective, most aircraft of course have to be certified for lightning, little ones and Ag etc. being the one that aren't.
Some of our composite structures do have metal in it however there are a lot of places that don't such a non-structural fairings. Also radomes do not have any metal since that would be an obvious issue.
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Old 04-03-2016, 11:46   #15
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Re: Lightning Strike - EPIRB etc

An EPIRB typically is exposed, and most vulnerable, when it is an auto-launch type designed to float off and turn itself on in the event you sink or roll over without any time for a human to toss it in. But unlike other electronics, it is isolated from the entire electrical system. There's no power connection, no ground, no big antenna. So lightning has no incentive [sic] to travel through an EPIRB on or below deck.
Lightning basically will always take the path of least resistance to ground, and that's usually from a tall metal object straight down, if it can. What kills the electronics in boats, is flashover from one path to another, or a direct strike traveling through connected wires, or an "induced current". That is, if there is any long conductor, straight or coiled, and that conductor is next to a path that lightning is traveling on, the high power will induce a secondary voltage on any nearby long wiring run, etc. even if they are not physically connected.
This is the same process that is used for electromagnetic devices, like your alternator or generator. Power going through one of two "close but separate" lines, induces power in the other line.
And a Faraday cage works by allowing that power to flow around it, on the skin of the cage, so there is no reason for the power to be induced through it, to the objects being protected inside.
Could the EPIRB on deck still be fried from stray current that way? Probably. Just very low odds, unless it was mounted "in" the main ground path. It couldn't hurt to have a second one in the abandon ship kit, or kept in the stove (or better metal box) since even without lightning, deck mounted EPIRBs (and life rafts) get ripped off and float away when you really don't want them to.


FWIW the only lightning damage I've taken was to my CAR, which was parked under a large overhanging tree during a storm. When I got back in, there was no sign of any damage--except one 15A ATO type fuse was blown, for no reason. Apparently one of the longer wiring runs in the car managed to generate enough induced voltage from one of the very close strikes, to blow a fuse.


So it isn't limited to boats and planes. Friends don't send friends golfing with umbrellas during lightning storms, either.(G)
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