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06-07-2021, 19:22
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#16
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Moderator
Join Date: Jan 2010
Location: Minnesota
Boat: Tartan 3800
Posts: 4,759
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Re: Near misses of lighting - use ferrite beads to reduce induced voltage spike?
Quote:
Originally Posted by MathiasW
So, why not liberally add ferrite beads at strategic places in plus and ground lines. (Data lines would also pick up surges, but beads would probably change the shape of the data signals and may create more problems there...)
Any thoughts on this idea? Crazy?
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It is a widely used strategy in the industry.
At one of my previous jobs we had a lab available to us with equipment that would produce deliberate discharges to stimulate static and lightning and a wand that would be applied by a technician to connectors and exposed surfaces of the device under test.
To be clear, we did not simulate "direct" hits (scare quotes because a direct hit is a poorly defined thing). We simulated particular waveforms based on Joules, peak voltage, rise time, etc.
High speed signal lines are the most difficult as ferrites (and capacitors) will tend to degrade the signal quality. Differential pairs with common mode chokes are one strategy. The cost of signal isolation and protective circuitry is a good deal of the cost of a twisted-pair Ethernet port, fwiw.
__________________
The best part of an adventure is the people you meet.
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06-07-2021, 21:36
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#17
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Senior Cruiser
Join Date: Oct 2007
Location: San Antonio, TX/Bocas del Toro, Panama
Boat: 1990 Macintosh 47, "Merlin"
Posts: 2,844
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Re: Near misses of lighting - use ferrite beads to reduce induced voltage spike?
As a recent victim of a neighbor's lightning strike... Best we can tell, our damage came through the water, and our ground bonding system. Most of what it took out is the network of our various network connected Raymarine electronics. Some others as well, but the big ticket items were networked. They power on, they just don't communicate.
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10-07-2021, 14:27
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#18
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Registered User
Join Date: Aug 2019
Location: New England
Boat: Building myself... FTW
Posts: 183
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Re: Near misses of lighting - use ferrite beads to reduce induced voltage spike?
Quote:
Originally Posted by bstreep
As a recent victim of a neighbor's lightning strike... Best we can tell, our damage came through the water, and our ground bonding system. Most of what it took out is the network of our various network connected Raymarine electronics. Some others as well, but the big ticket items were networked. They power on, they just don't communicate.
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Bstreep,
Sorry for your loss. I have a morbid curiosity and would like to ask a couple of questions.
How many nodes/devices are on this network?
Is this a Raymarine topology/CAN/Serial network or a an ethernet network?
Was this network directly cabling directly wired to your ground or indirectly tied to ground?
Do you have a rough estimate of the overall length of cables in the network?
Thank you, for any extra details you can provide.
Ben
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12-07-2021, 22:25
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#19
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Senior Cruiser
Join Date: Oct 2007
Location: San Antonio, TX/Bocas del Toro, Panama
Boat: 1990 Macintosh 47, "Merlin"
Posts: 2,844
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Re: Near misses of lighting - use ferrite beads to reduce induced voltage spike?
Quote:
Originally Posted by bdgWesternMass
Bstreep,
Sorry for your loss. I have a morbid curiosity and would like to ask a couple of questions.
How many nodes/devices are on this network?
Is this a Raymarine topology/CAN/Serial network or a an ethernet network?
Was this network directly cabling directly wired to your ground or indirectly tied to ground?
Do you have a rough estimate of the overall length of cables in the network?
Thank you, for any extra details you can provide.
Ben
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Yes, it's Raymarine. Seatalk NG. Connection to ground was only via a negative from the power supply wiring, from the 12v ground. So, indirectly. Seatalk carries 12v, but it's supplied from either our chartplotter, or our autopilot. Chartplotter was not plugged in.
Our Seatalk cables run from just behind the mast, to the stern, and then back up to the wheel. We are a 47' center cockpit. Probably 70-90' of network cable.
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13-07-2021, 04:08
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#20
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Registered User
Join Date: Aug 2019
Location: New England
Boat: Building myself... FTW
Posts: 183
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Re: Near misses of lighting - use ferrite beads to reduce induced voltage spike?
Quote:
Originally Posted by bstreep
Yes, it's Raymarine. Seatalk NG. Connection to ground was only via a negative from the power supply wiring, from the 12v ground. So, indirectly. Seatalk carries 12v, but it's supplied from either our chartplotter, or our autopilot. Chartplotter was not plugged in.
Our Seatalk cables run from just behind the mast, to the stern, and then back up to the wheel. We are a 47' center cockpit. Probably 70-90' of network cable.
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Thank you for the additional details. I wonder if the Seatalk grounding is considered a "floating ground" in this configuration.
I also am curious if you know if the chassis of the Seatalk devices was grounded.
This real world experience is really interesting to me.
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13-07-2021, 04:33
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#21
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Registered User
Join Date: Jan 2011
Location: Caribbean live aboard
Boat: Camper & Nicholson58 Ketch - ROXY Traverse City, Michigan No.668283
Posts: 6,353
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Re: Near misses of lighting - use ferrite beads to reduce induced voltage spike?
We have installed double pole switches to provide an air gap when off for every electronic device. The power off button on all modern equipment is a soft start circuit so for example, your radio inlet power is still connected to the boat. The negative is always connected. Add in the air gap break on both plus and minus and the device is not part of the boat. We also have a big 48 pin connector at the foot of the mast to disconnect all mast wires. Leave a quick connect in an accessible location for antenna coax. We have been struck three times. I have never lost electronics connected (disconnected) this way.
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13-07-2021, 05:25
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#22
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Senior Cruiser
Join Date: Mar 2003
Location: Thunder Bay, Ontario - 48-29N x 89-20W
Boat: (Cruiser Living On Dirt)
Posts: 49,087
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Re: Near misses of lighting - use ferrite beads to reduce induced voltage spike?
Quote:
Originally Posted by Nicholson58
We have installed double pole switches to provide an air gap when off for every electronic device...
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You can consider an airgap to have an impulse withstand of about 1kv per 1.5mm of airgap. Many protection switches have physical barriers between the contacts, to increase the air distance between them.
A “double-make double-break style” prevents Lightning from passing through, from side-to-side, because the shorting bar is grounded when not energized. Any arcs across contacts would go to ground.
Nicholson's double pole recommendation would require two 'DMDB' devices [1 ea. pos. & neg.]
A double-make double-break looks like this:
__________________
Gord May
"If you didn't have the time or money to do it right in the first place, when will you get the time/$ to fix it?"
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13-07-2021, 05:53
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#23
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Registered User
Join Date: Aug 2019
Location: New England
Boat: Building myself... FTW
Posts: 183
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Re: Near misses of lighting - use ferrite beads to reduce induced voltage spike?
Quote:
Originally Posted by Nicholson58
We have installed double pole switches to provide an air gap when off for every electronic device. The power off button on all modern equipment is a soft start circuit so for example, your radio inlet power is still connected to the boat. The negative is always connected. Add in the air gap break on both plus and minus and the device is not part of the boat. We also have a big 48 pin connector at the foot of the mast to disconnect all mast wires. Leave a quick connect in an accessible location for antenna coax. We have been struck three times. I have never lost electronics connected (disconnected) this way.
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Yes, that sounds quite thorough.
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13-07-2021, 05:57
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#24
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Registered User
Join Date: Aug 2019
Location: New England
Boat: Building myself... FTW
Posts: 183
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Re: Near misses of lighting - use ferrite beads to reduce induced voltage spike?
Quote:
Originally Posted by GordMay
You can consider an airgap to have an impulse withstand of about 1kv per 1.5mm of airgap. Many protection switches have physical barriers between the contacts, to increase the air distance between them.
A “double-make double-break style” prevents Lightning from passing through, from side-to-side, because the shorting bar is grounded when not energized. Any arcs across contacts would go to ground.
Nicholson's double pole recommendation would require two 'DMDB' devices [1 ea. pos. & neg.]
A double-make double-break looks like this:
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That sounds very thorough. The drawing looks like the big cylinder comes down to make the connection, but I think it must be that grounded part moves up to make the connection.
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13-07-2021, 06:01
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#25
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Senior Cruiser
Join Date: Mar 2003
Location: Thunder Bay, Ontario - 48-29N x 89-20W
Boat: (Cruiser Living On Dirt)
Posts: 49,087
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Re: Near misses of lighting - use ferrite beads to reduce induced voltage spike?
Quote:
Originally Posted by bdgWesternMass
That sounds very thorough. The drawing looks like the big cylinder comes down to make the connection, but I think it must be that grounded part moves up to make the connection.
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Yes. It's actually a dwg of a magnetic relay [coil at top, moving contacts at bottom].
__________________
Gord May
"If you didn't have the time or money to do it right in the first place, when will you get the time/$ to fix it?"
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13-07-2021, 06:08
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#26
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Registered User
Join Date: Jan 2011
Location: Caribbean live aboard
Boat: Camper & Nicholson58 Ketch - ROXY Traverse City, Michigan No.668283
Posts: 6,353
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Re: Near misses of lighting - use ferrite beads to reduce induced voltage spike?
Gord,
Any method used needs to also disconnect the negative side of the device as well. The last VHS radio I lost before adding my DPST switch had the rectifier input switching board fried apparently from the negative side. I postulate the negative, very large wire loom throughout the boat can be a source for induced power back fed into electronics. Not sure I follow all there is to your diagram.
In our last hit, Muskegon, Michigan, witnessed by a charter fishing crew at 2 AM, we received a direct strike to the top of our main mast. Branch strikes jumped from Roxy to two other boats. Two additional boats were struck elsewhere in our marina. We lost
Vesper AIS
Stereo entertainment system
18 glass BUSS fuses
60 amp shore power breaker
Aux alternator
Xantrex was wonky but working. Died later
Autopilot controller
Windex wind indicator vaporized
Two VHS antennas
All cabin lighting wires in the forward cabin
8 interior LED cabin lights
3 LED deck lights on spreaders
All LED nav lights, both masts
Raymarine wind speed and direction
Transom paint crazed all around the bronze through hulls
I know I’ve forgotten a few. The ‘fuzzy’ lightening arrestor on top of the main managed to protect itself.
I lost none of my Simrad; chart plotter, depth sounder, radar. Also spared was the electronic barometer. These were all off by both breaker and double pole switch. This convinced me to go full on to add switches and cable breaks for everything else. Living aboard since 2016 we have seen no lightening until the monster tropical storm last November in English Harbor, Antigua. We had hours of flash-boom and 18 inches of rain. I had to scramble to remember my Great Lakes procedures. Fortunately, no issues but nobody else struck either.
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13-07-2021, 06:23
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#27
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Registered User
Join Date: Aug 2019
Location: New England
Boat: Building myself... FTW
Posts: 183
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Re: Near misses of lighting - use ferrite beads to reduce induced voltage spike?
Quote:
Originally Posted by Nicholson58
Gord,
Any method used needs to also disconnect the negative side of the device as well. The last VHS radio I lost before adding my DPST switch had the rectifier input switching board fried apparently from the negative side. I postulate the negative, very large wire loom throughout the boat can be a source for induced power back fed into electronics. Not sure I follow all there is to your diagram.
In our last hit, Muskegon, Michigan, witnessed by a charter fishing crew at 2 AM, we received a direct strike to the top of our main mast. Branch strikes jumped from Roxy to two other boats. Two additional boats were struck elsewhere in our marina. We lost
Vesper AIS
Stereo entertainment system
18 glass BUSS fuses
60 amp shore power breaker
Aux alternator
Xantrex was wonky but working. Died later
Autopilot controller
Windex wind indicator vaporized
Two VHS antennas
All cabin lighting wires in the forward cabin
8 interior LED cabin lights
3 LED deck lights on spreaders
All LED nav lights, both masts
Raymarine wind speed and direction
Transom paint crazed all around the bronze through hulls
I know I’ve forgotten a few. The ‘fuzzy’ lightening arrestor on top of the main managed to protect itself.
I lost none of my Simrad; chart plotter, depth sounder, radar. Also spared was the electronic barometer. These were all off by both breaker and double pole switch. This convinced me to go full on to add switches and cable breaks for everything else. Living aboard since 2016 we have seen no lightening until the monster tropical storm last November in English Harbor, Antigua. We had hours of flash-boom and 18 inches of rain. I had to scramble to remember my Great Lakes procedures. Fortunately, no issues but nobody else struck either.
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I really appreciate all this information and I hope you take this next question with the correct tone
Quote:
Originally Posted by Nicholson58
We have been struck three times. I have never lost electronics connected (disconnected) this way.
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There are a couple of ways I can reconcile these statements:
The electronics lost in that long list were not connected using dpdt switches.
You have been struck since this time but not in Antigua.
The method should work (especially using Gord's specs) but hasn't been tested with a lightening strike.
I'm trying to get a clear picture.
I hope everyone feels this thread is still on topic.
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13-07-2021, 07:13
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#28
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Registered User
Join Date: Jan 2011
Location: Caribbean live aboard
Boat: Camper & Nicholson58 Ketch - ROXY Traverse City, Michigan No.668283
Posts: 6,353
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Re: Near misses of lighting - use ferrite beads to reduce induced voltage spike?
Quote:
Originally Posted by bdgWesternMass
I really appreciate all this information and I hope you take this next question with the correct tone
There are a couple of ways I can reconcile these statements:
The electronics lost in that long list were not connected using dpdt switches.
You have been struck since this time but not in Antigua.
The method should work (especially using Gord's specs) but hasn't been tested with a lightening strike.
I'm trying to get a clear picture.
I hope everyone feels this thread is still on topic.
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The long list wrecked did not include the Simrad and barometer. They were aboard at the time. They were not damaged and were double pole switched. Nothing else was. My opinion, the DP switch should be very close to the device to minimize the possible induced voltage. Disconnecting totally makes the device similar to it sitting in a box on the galley table. Breaking the negative I view as critical. The VHF, Vesper, stereo were off and breakers off. This left only the ground circuit connected. They were fried as I noted on their negative side of the power wire rectifier soft start board. I suspect that on a hit, the entire ground wire system of your boat may become powered either directly or by induction. It is after all a very large antenna at that point. I disassembled all wrecked items except the Vesper. The damage on electronics was always as I noted so at least on that hit, my negative became charged. The Vesper went to New Zealand for rebuild. They also confirmed the same damage to the input start and power board. My alternator had all diodes blown and the safety interrupt opened. The main shore power 60 amp two pole breaker had one leg blown. The inside was a mess of copper coating everything. This was a massive strike as I noted and well observed. My deck was covered with SS balls like solder spatter from the remains of the antennas and Windex. The other boats all lost major gear as well. I have to conclude that all of my I damaged devices would surely have been wrecked too except for the DP switches, the only notable difference.
You are correct as far as we know, the boat has not been struck since installing the mess of switches. We are not on the boat June to November, hurricane and storm season. There have been numerous storms while the boat waits out storm season but we have no idea regarding strikes. We leave all switches off, breakers off, mast wire plug pulled, antenna coax disconnected. All that remains powered I’d the bilge pump. Roxy is currently in Jolly Harbor, Antigua. We prefer Trinidad but not possible lately. Fortunately, both places are surrounded by tall mountains.
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13-07-2021, 07:16
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#29
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Registered User
Join Date: Aug 2019
Location: New England
Boat: Building myself... FTW
Posts: 183
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Re: Near misses of lighting - use ferrite beads to reduce induced voltage spike?
Great thanks for the clarification. I definitely think I will minimize my conductive footprint and have a complete disconnect for DC currents.
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13-07-2021, 07:19
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#30
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Marine Service Provider
Join Date: Feb 2020
Location: www.trimaran-san.de
Boat: Neel 51, Trimaran
Posts: 448
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Re: Near misses of lighting - use ferrite beads to reduce induced voltage spike?
Quote:
Originally Posted by Nicholson58
We have installed double pole switches to provide an air gap when off for every electronic device. The power off button on all modern equipment is a soft start circuit so for example, your radio inlet power is still connected to the boat. The negative is always connected. Add in the air gap break on both plus and minus and the device is not part of the boat. We also have a big 48 pin connector at the foot of the mast to disconnect all mast wires. Leave a quick connect in an accessible location for antenna coax. We have been struck three times. I have never lost electronics connected (disconnected) this way.
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Thank you! All very valuable information. From this I take it that the damage is NOT done by inducing voltage INSIDE the device, as some earlier responses at suggested, as your double switch would not protect against that.
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