Lightning, and what to do about it

[transmitterdan]

Storm fronts are also easily observed on radar. I use mine a lot for that purpose.

[Cpt Pat]

Originally Posted by Talos

As mentioned above, knowing that there is lightning in the area "Situational Awareness" is the first step for safety. By putting your backup navigation tool (iPad .. others) and your handheld VHF in the microwave or other safe location is a smart move. The Talos Lightning detector will alert you when the storm front/lightning front is up to 25 miles away and alerts you if it is approaching .. or departing the area. Mention the Cruising Forum and receive 10% off. Also great to carry one in the dink .. you are the highest point ... a heads up to get back to the mothership ... www.shopTalos.com

I watch the demo video. That looks like a very useful product. I had a Sperry Stormscope (salavaged from an aircraft) on my Westsail 32. I was a big hunk of expensive hardware.

Is the lightning detector tolerant of VHF radio transmissions? I don't want my AIS setting it off (the antenna is 20 feet away from the cabin). I presume it detects radio bursts in the MF/low HF spectrum.

[barnakiel]

Copper wires are only somewhat effective. A sound prayer is way better.


Also if you are not religious (like me).


barnakiel

[Steve DAntonio]

Having worked on the Chesapeake Bay for much of my career, I have dealt with lightning both personally and professionally. While Fl is the US lightning capital of the US, the number of boats struck on Ches Bay is considerable, and the ferocity of the storms, rolling off the Blue Ridge Mountains as they do, are unlike anything I've ever seen; when I managed a yard there, their wasn't a summer that went by that we didn't deal with several lightning strikes, in one case the same boat was struck twice. My property was hit at least 5 times that I knew of, with varying degrees of damage, thankfully none very serious. Ultimately I surge protected all the electrical and electronic gear, networks etc.

Lightning is a subject I've studied and written about on several occasions. I can find no reputable source that can describe a system that verifiably prevents lightning strikes. There's plenty of theory and claims, but nothing definitive or proven. Any time I hear someone claim it can be done, my BS meter starts to go into the red zone.

PS has a booklet on the subject, written by EE Stan Honey. Stan is very sharp, but the publication, and his claims, are dated IMO (I critiqued it for the editor just a few weeks ago), today few pro's will go so far as to say there's a proven system for small craft lightning strike prevention.

I'm headed to FL next week to review a recently-struck cat...

More on lightning protection here https://www.proboat.com/2016/04/3530/

And this very good article written by a colleague https://www.boatus.com/seaworthy/mag...protection.asp

(In Taiwan)

[echomax]

The unit you need is a CMCE-25

https://www.preventlightning.com/marine

[echomax]

The unit you need is a CMCE-25

https://www.preventlightning.com/marine

[Frankly]

CMCE

On a scale of 0 to 10 my BS meter is reading 9.8.


Frankly

[fcallard]

Originally Posted by onestepcsy37

i have posted before on our lightning experience.

short story.

most or all of your electronics have a fuse on the positive wire. put a fuse on the negative wire as well.

the only piece of electronics that survived was our navtex. it came with a negative wire fuse, which was blown. i replaced the fuse and it started right up.

none of the positive wire fuses were blown on any of our electronics.

We’ve had 2 lightning strikes: one was a side strike and the other was a direct strike (blew the VHF whip off the mast).

In the indirect hit, we noted that our VHF had inline fused on both wires and they looked like popped flash bulbs. The VHF didn’t work. We also had a removable AP control box that was sitting on a shelf, not connected to anything, and it didn’t work either. We lost all of our electronics in both strikes.

A direct strike that electrifies your wiring is one thing, but there is another problem in an indirect strike with the high voltage electromagnetic fields associated with the lightning discharge that can radiatively couple to your electronic circuits and easily exceed the semiconductor breakdown voltages. One term used for this effect is electromagnetic pulse (EMP).

So, you can use all the fuses you want, but if lighting can close a 1000’ gap between cloud and the surface, it won’t have a problem jumping the gap in an open breaker or the gap created by an open fuse.

Best bet: buy a proper insurance policy that provides for replacement of your electronics with no depreciation. Worked for me!

[Frankly]

There is one point that most seem to miss. While the voltage required to produce a lightning discharge is in the million(s). Once a discharge path through your mast is established, the pretty well understood laws/physics of electricity are in effect. If the impedance of a well grounded mast is say one Ohm to seawater, and the peak current is 10,000 amps, then the common mode voltage on the mast and rigging is going to be 10,000 Volts. Not a trivial potential but not the end of the world (power line in front of my house 6,770 Volts). If your ungrounded masts exhibits an impedance of say 1000 Ohms, then you are in the million(s) voltage range. At that level prayer and insurance are viable options.


Frankly

[Q Xopa]

Originally Posted by Frankly

There is one point that most seem to miss. While the voltage required to produce a lightning discharge is in the million(s). Once a discharge path through your mast is established, the pretty well understood laws/physics of electricity are in effect. If the impedance of a well grounded mast is say one Ohm to seawater, and the peak current is 10,000 amps, then the common mode voltage on the mast and rigging is going to be 10,000 Volts. Not a trivial potential but not the end of the world (power line in front of my house 6,770 Volts). If your ungrounded masts exhibits an impedance of say 1000 Ohms, then you are in the million(s) voltage range. At that level prayer and insurance are viable options.


Frankly

Not many have quantified the concept using a ohms law figures example.

However most people, that are not in the 'prayer' camp, agree in using low resistance conductor path to ground.

[fcallard]

Originally Posted by Frankly

There is one point that most seem to miss. While the voltage required to produce a lightning discharge is in the million(s). Once a discharge path through your mast is established, the pretty well understood laws/physics of electricity are in effect. If the impedance of a well grounded mast is say one Ohm to seawater, and the peak current is 10,000 amps, then the common mode voltage on the mast and rigging is going to be 10,000 Volts. Not a trivial potential but not the end of the world (power line in front of my house 6,770 Volts). If your ungrounded masts exhibits an impedance of say 1000 Ohms, then you are in the million(s) voltage range. At that level prayer and insurance are viable options.


Frankly

Just a note on the physics. When you electrify a conductor (mast, shrouds) at high voltage, there will be a sheath of ionized air (called a “corona”) created that will likely conduct many orders more power that the metallic conductor itself.

[lucyrabbit]

I am in Hong Kong and we have our fair share of lightning strikes here too...a mix of sheet and bolt and the way I have seen these systems recently, is one of bolt lightning hits on one boat causing a spread of secondary strikes to closely moored boats. In my case, my next door neighbour had a direct hit and I received his secondary voltage effects that took out most of the Nav platforms, bilge system, genset, fridge system and engine alternators. The alternators were destroyed through the diodes but I have recovered the bilge, fridges and replaced the alternators with new.
The "parent" strike on my neighbour, took out ALL his electrics and pretty much cooked his wiring. The aspect of sheet effect seems more to "soft" strike and upset the balance of finely tuned electrics such as autopilot and chart plotters. My nav platform is B andG..I had Raymarine for over 12 years and that weathered many electrical storms without bother..it has made me wonder if some brands are more prone to electrical upset than others?
If there is any knowledge out there WRT generator electrical integrity and replacing of voltage regulator/alternator, boards etc, then glad to receive...buy yes, I agree with the general presumption that much is spoken about this phenomena but little is known...!!!

[Q Xopa]

Originally Posted by lucyrabbit

I am in Hong Kong and we have our fair share of lightning strikes here too...a mix of sheet and bolt and the way I have seen these systems recently, is one of bolt lightning hits on one boat causing a spread of secondary strikes to closely moored boats. In my case, my next door neighbour had a direct hit and I received his secondary voltage effects that took out most of the Nav platforms, bilge system, genset, fridge system and engine alternators. The alternators were destroyed through the diodes but I have recovered the bilge, fridges and replaced the alternators with new.
The "parent" strike on my neighbour, took out ALL his electrics and pretty much cooked his wiring. The aspect of sheet effect seems more to "soft" strike and upset the balance of finely tuned electrics such as autopilot and chart plotters. My nav platform is B andG..I had Raymarine for over 12 years and that weathered many electrical storms without bother..it has made me wonder if some brands are more prone to electrical upset than others?
If there is any knowledge out there WRT generator electrical integrity and replacing of voltage regulator/alternator, boards etc, then glad to receive...buy yes, I agree with the general presumption that much is spoken about this phenomena but little is known...!!!

Sorry for your loss. I know of a number of similar stories personally.

Here in Panama where it seems quite common. A buddy of mine was hit 3 times, each time taking out a large number of his electronics. His Insurance company wiped him the 3rd claim. Which I can understand it does sound dodgy, but was acually true. We joked with him that he was unlucky and Im not anchoring near him. But really its not nice. This was over a period of a few years, the last 3 years ago.

Another one of my neighbors more recently got hit, everything fried including his starter, so he couldnt even motor home. He's now saving trying to get stuff replaced. His attitude is that there's no way to mitigate this risk. Essentially they both had no Lightening strike measures. From what I see, this seems the common approach.

I have taken their losses to heart and researched if or how we can potentially minimise damage.

Using some hopefully good information out there AYBC and others, I have put a 1/2" rounded end copper rod/ 'air terminal' on my masthead. 6" higher than anything else, ie my VHF Antenna. 2AWG conductors with 8" min bend radius. To long 2" W x 1/4" T copper strips, basically from the mast either side to the transom, for Grounding bars. Apparently some people machine grooves in them to increase surface area, which is what matters. I didnt go to this extent.

I dont know if this will work. The experts seem to think it gives you a good shot at survival. Hopefully it doesnt get put to the test.

But I figure for, in the boat scheme of things, its a reasonably small cost, well under a Boat buck, and a bit of my time and effort its cheap insurance, and worth a go.

If I was religous I would give prayer a go too.

Can we ask what, or if, you or your neighbor had in the way of lightning conductors?

[lituya1617]

The lightening strike on a boat is a rapidly traveling wave of very high voltage electricity. Simple physics requires that a very high amplitude magnetic field travels right along with the bolt of lightening. This rapidly moving field cuts through conductors (wires) in all boat electronics and INDUCES a large voltage spike with a rise time (time to go from no voltage to maximum voltage induced) that is very short, often less than a millisecond. No transistor system can withstand voltages of hundreds of volts! Surge protectors are OK for nearby lightening strikes because the amplitude of the magnetic pulse falls off as the cube of the distance from the strike; HOWEVER, no known surge protector can prevent a catastrophic voltage spike from a direct hit from lightening. Transistors fail around 2 - 5 volts and many fail at 1.7 volts. Integrated circuits cannot withstand the magnetic pulse/voltage spike typical of a lightening strike. It is not a matter of having fuses on both the negative and positive feeds to your electronics. Very high voltage will pass right through the air gap of a blown 12 volt fuse. Commercial radio stations have expensive, bulky systems that protect their transmitters but these are not of much use on a boat. Also, the little building at the base of transmitter towers are built much like a Faraday Cage so the only voltage/magnetic spike entering the building is contained to the antenna and power wires which are usually isolated by a battery-like and large tuned and grounded resistor/inductor that easily passes only a certain frequency while large spikes are shunted to ground. Power input has another type of isulator that uses an inductive shunt and often interposes a battery and inverter system to prevent throughput of voltage spikes. Even with all this, transmitters often fail with a direct strike. A Faraday Cage will protect any electronics totally contained within it and having no connections (wires) outside the cage. Obviously, your depth sounder, chart plotter, autopilot, alternator (yep, they have a type of transistor in them called diodes) and LED lights are not very useful inside a Faraday Cage disconnected from their usual locations and connections. Bottom line: a direct strike will fry your electronics and anything with transistors in it. Not much you can do about it unless you go low-tech. I carry extra diode sets for my alternator. I put my cell phone, GPS, hand held VHF, EPIRB, depth sounder head, in a home-made Faraday Cage when lightening is within 20 miles. There are YouTube videos showing how to build a cage. It's basically a metal can. A microwave oven is said to be a good approximation to a cage. I do not know if they work. You can hear the lightening if you use an AM radio not tuned to a station and listen for the crackles of lightening; it's quite distinctive. Sometimes the best you can do is accept fate.

[Frankly]

"Just a note on the physics. When you electrify a conductor (mast, shrouds) at high voltage, there will be a sheath of ionized air (called a “corona”) created that will likely conduct many orders more power that the metallic conductor itself."

My observation of strikes over the years (a couple too close for comfort) as far as the the visible phenom of the process (corona, plasma, ionized air, ect). When lightning strikes a poor conductor (usually a tree) the visible strike will continue all the way to the ground. When lightning strikes a well grounded structure (tower, static power line, ect) there is (in my observations) no visible part apparent from the conducting structure. That would in some instances support the above, if a well grounded structure/ mast limits the common mode voltage below the level to produce the ionization.


The cell phone video of a strike of an ungrounded sailboat mast (widely circulated last year) would support this. The visible strike was head to toe. Keep in mind a 10,000 amp strike is a different animal from a 200,000 amp discharge.


Frankly