Lightning prevention system.

[Retirement home]

My mum bought me a snake chaser..
Supposed to guarantee snakes would not come near.
(Living next to a large open long grass field)
It is a vibration stake..

Watching the Simpson's I recall a big black dude with a dark bass voice whom snakes loved because of vibration.

Any how.. that season I had a venomous snake nest in back yard.

Did the opposite.

LOL
Anyone for soft shelled eggs? All hatched. Beautiful creatures. Strangers again. No more ground vibration, no more snakes.

[s/v Jedi]

Originally Posted by team karst

Dissipation or transfer? My understanding is these aircraft wicks transfer electron movement away from the antennas, improving comm and nav functions.

They dissipate static charge. If they wouldn’t do that, you build it up until it discharges with flaming effects, instead of continuously like with the dissipator.

Those built up discharges with sparks are interfering with radio communications.

The LM uses the exact same principles to work against building up the static charge, delaying it compared to other objects in the area, hoping that the other objects win the election for forming the upwards leaders that define the path of the strike.

The last link I posted explains the principle pretty good.

[s/v Jedi]

Originally Posted by GordMay

IIRC, NFPA 780 does not cover lightning protection installation requirements for early streamer emission systems or lightning dissipater array systems.

The good thing is that the LM, when it fails to escape the strike, will function like a standard lightning rod conform NFPA780.

[Montanan]

Originally Posted by s/v Jedi

You can not prevent a lightning strike but you can influence where the strike hits. When the atmosphere is charged, many leaders start to form and those are required for the strike to trigger. Not all forming leaders attract a strike.

Read up on St Elmo’s fire.

Mitigation is #1 priority. For monohulls it can 100% protect against sinking from holes blown through the hull or blown out skin fittings. For catamarans it is much more difficult but still a high level of protection is achievable.

Damage to electronics is not really preventable.

I have seen St. Elmo's plasma glow and hiss on metal objects two times.

During a thunderstorm, as a young child in Nebraska, an occurrence of ball lightening formed (a luminescent spherical glowing object) that was about the size of a tennis ball in the hall way leading from our living room towards our bedrooms. It floated slowly down the hallway towards me, and I ran into my adjacent bedroom and watched as it passed by and it silently and non-destructively dissipated into the wall at the end of the hallway as if it was passing through the wall. It was present for about 15 to 20 seconds. It wasn't really scary, just very strange and kind of disconcerting to have it float towards me.

https://en.wikipedia.org/wiki/Ball_lightning

[Frankly]

If nothing else came out of this wide ranging discussion, got me off my can to finish something before Summer Thunderstorms really kick in.

I will report any negative outcomes, positive outcomes hard to ascertain (thought about remote mic to listen for corona discharges).


" May the Force Be With You" and the discharges somewhere else.

[franksingleton]

It has been interesting to me. What would be interesting would be to hear from those who actually have the LM. Much of the input has been theory or opinion without hands on experience of the LM, itself. My initial input was direct experience of the LM. I have seen none from others with real experience. Any takers?

[smj]

Originally Posted by franksingleton

It has been interesting to me. What would be interesting would be to hear from those who actually have the LM. Much of the input has been theory or opinion without hands on experience of the LM, itself. My initial input was direct experience of the LM. I have seen none from others with real experience. Any takers?

If this is an LM,

Then the LM showed signs of being struck by lightning on the boat we purchased. Just to clarify, the boat was struck by lightning and the ends of the small wires on the LM were melted balls.

[Frankly]

Interesting, since there are numerous examples of SS VHF whips turned to scrap metal one would think that if the LM were to take a direct hit the remaining wires it would resemble a buzz cut.

Hope the damage was not too severe.

Just as I was posting my picture this afternoon we had a strike so close it shook the house. Probably see a dead tree (what few are left) in a few months.

Buckle up your seat belt and sail on, none of us gets out alive.


Frankly

[s/v Jedi]

Originally Posted by smj

If this is an LM,
Attachment 258253
Then the LM showed signs of being struck by lightning on the boat we purchased. Just to clarify, the boat was struck by lightning and the ends of the small wires on the LM were melted balls.

That wasn’t a direct strike because only part of the main rod would have been left in that case. None of the thin pointy wires would have been left.

I would actually think it worked and if there was a direct strike (burned out starter motor or other severe damage) then there is probably another point where lightning hit, like SSB antenna (check tuner inside) or any ungrounded metal parts.

[s/v Jedi]

Originally Posted by franksingleton

It has been interesting to me. What would be interesting would be to hear from those who actually have the LM. Much of the input has been theory or opinion without hands on experience of the LM, itself. My initial input was direct experience of the LM. I have seen none from others with real experience. Any takers?

I reported many times about our LM’s.

[smj]

Originally Posted by s/v Jedi

That wasn’t a direct strike because only part of the main rod would have been left in that case. None of the thin pointy wires would have been left.



I would actually think it worked and if there was a direct strike (burned out starter motor or other severe damage) then there is probably another point where lightning hit, like SSB antenna (check tuner inside) or any ungrounded metal parts.

Did the LM work? If I was the guy that spent big bucks to put the metal toilet brush on top of the mast then maybe I could be convinced.
Only electronics that were affected were the vhf and stereo, both sharing the same vhf antenna. Yet there were some small pinholes on the insides of each hull and about a 1/2” hole right above the waterline. Carbon fiber mast still looks and performs as if it were new.
Would be great if I knew what path the strike took or if it were a direct hit, but I don’t and honestly don’t think anyone does.

[Frankly]

With a carbon fiber mast, the cap shrouds most likely carried the majority of the current pulse. Sounds like things did not turn out as bad as a others have reported.

Never had a hole in my hull, but over the years I have replaced 2 inverter chargers, full set of instruments, radar, autopilot, and just last fall my anchor windlass/ bow thruster wireless control unit and don't think I have ever taken a direct hit. Just several near misses.

Still think highways are far more dangerous places to be.


Frankly

[CatLove]

Does anyone have experience with lightning detection/warning devices? The cheap ones can measure the distance to a lightning storm and its intensity, the expensive ones can also display storm direction . I've seen these on land and airplanes but not on boats.

[s/v Jedi]

Originally Posted by smj

Did the LM work? If I was the guy that spent big bucks to put the metal toilet brush on top of the mast then maybe I could be convinced.
Only electronics that were affected were the vhf and stereo, both sharing the same vhf antenna. Yet there were some small pinholes on the insides of each hull and about a 1/2” hole right above the waterline. Carbon fiber mast still looks and performs as if it were new.
Would be great if I knew what path the strike took or if it were a direct hit, but I don’t and honestly don’t think anyone does.

Holes in the hull indicate direct strike. I would investigate further because there can be hidden damage. The lightning went through the fiberglass but it jumped from some conductive object near that hole (every hole). Finding those objects show clues for places to look next.

I don’t think it came down the mast because that would have destroyed the mast. I agree that it probably hit the rigging and came down that way. Unless the antenna was vaporized, the damage to VHF and radio is probably from a transient surge caused by the field picked up by the antenna.

For a LM to work, it must be grounded and all metal parts that stick up from the boat must be grounded as well or they risk to get struck.

[smj]

Originally Posted by s/v Jedi

Holes in the hull indicate direct strike. I would investigate further because there can be hidden damage. The lightning went through the fiberglass but it jumped from some conductive object near that hole (every hole). Finding those objects show clues for places to look next.



I don’t think it came down the mast because that would have destroyed the mast. I agree that it probably hit the rigging and came down that way. Unless the antenna was vaporized, the damage to VHF and radio is probably from a transient surge caused by the field picked up by the antenna.



For a LM to work, it must be grounded and all metal parts that stick up from the boat must be grounded as well or they risk to get struck.

The insurance company hired a company that specialized in lightning strikes to thermal image the boat and rig. This occurred 5 years ago and no other findings.
When we had the boat surveyed before purchase our surveyor found an area with high moisture content that would have to be ground out and repaired. After being ground out there wasn’t a drop of moisture to be found, another thumbs down for the moisture meter in my books, or maybe the way the surveyor interpreted the moisture meter?