LIGHTNING DETAILS -Risk Management

[GTom]

Originally Posted by boatman61

Low level sheet lightning.. wiped out all electrics that were in use at the time.. Nav lights, VHF, Tiller Pilot, GPS etc..
Batteries and wiring were fine but instruments and bulbs needed replacing.

That makes me rethink why on earth have I bought the more expensive navlights, plotter, solar controller...

I wonder if any of the active instruments can be protected? The solar controller (I know, just 200€) can live in a metal box + some frequency filters added on the wires...

[puffcard]

Originally Posted by Cadence

I'd be suspect of hi-pot shorts in wiring bundles after a lightening strike.

After last strike, couldn't start the boat because it had open in the dc ground in a couple places from the heat and arcing. Seems the big highway for the strike is your gound/plane. Which everything is hooked up to with zero protection.

[Cadence]

Originally Posted by GTom

That makes me rethink why on earth have I bought the more expensive navlights, plotter, solar controller...

I wonder if any of the active instruments can be protected? The solar controller (I know, just 200€) can live in a metal box + some frequency filters added on the wires...

I don't know I would worry about it. You have as much chance of winning a high $ lotto.

[boatman61]

Originally Posted by Cadence

I'd be suspect of hi-pot shorts in wiring bundles after a lightening strike.

Don't think it was an actual strike.. just the sheet was low enough to cause a surge that blew the instruments.. and the guy from Pantaenius cleared everything else as good to go.. doubt he'd have done that if it was not.
It was a KISS boat after all..

[Jammer]

Originally Posted by Pelagic

Why makes aircraft safe flying near or thru thunderstorms?

Aircraft try to avoid thunderstorms because of the wind and turbulence, by flying over or around them. When aircraft go through a storm, they spend as little time as possible in it. So they aren't exposed to storms much while operating.

And, to some extent, the aluminum skin forms a Faraday cage.

If lightning struck the stainless Mast Caps of my wooden Masts, would it not just travel down the path of leat resistance....i.e the heavy rigging to hull and dissipate in salt water?

The problem is that the enormous current pulse in the rigging, around 10,000 amps, is enough to create large induced voltages in other conductive objects nearby. You probably also have an antenna and masthead light, and the wiring for those will take part of the hit.

[Jammer]

Originally Posted by GTom

Yupp, that's the EMP. I am shopping for my new boat and a few metal boxes are definitely on the list, but I have to educate myself which ones qualify.

The most practical thing to use is an aluminum box with a tight-fitting lid.

Here are a bunch of them to consider, various sizes:

https://www.alliedelec.com/enclosure...0Manufacturing

You can also just wrap the items to be protected in a couple of layers of aluminum foil.

Steel boxes will also work reasonably well. A piece of copper pipe with copper caps on each end will work, and is ideal for smaller items.

[Jammer]

Originally Posted by Cyrus Safdari

FYI folks Faraday cages only work if they're grounded. Your oven probably isn't.

That is not true.

[Cadence]

Originally Posted by boatman61

Don't think it was an actual strike.. just the sheet was low enough to cause a surge that blew the instruments.. and the guy from Pantaenius cleared everything else as good to go.. doubt he'd have done that if it was not.
It was a KISS boat after all..

I hope not. I had a truck hit while driving down the road. I saw it hit the hood, I'm still here so I guess Faraday's cage works. It died on the spot but had crazy things happen with the electronic continually after repeated dealer visits.
I traded a beloved truck, they were never going to replace all the wiring harnesses. Who know where the pin holes here in the insulation. Just a thought on the effect of a lightning strike and wiring. Going from wire to wire with a mega might find them, what a no. of combinations. A boat might be easier.

[Jammer]

So, what can you do.

You can try ground the mast, either to a grounding plate or a conductive hull.

You can pressure your electronics vendors to do a better job of protecting the power and I/O against surges. It is not possible to build electronics that are lightning proof. It is very much possible to build electronics that are less likely to to be damaged by a lightning strike elsewhere in the boat.

For the VHF, there are lightning arresters that go in the coax. Ideally they would be at the base of the mast (or where the coax exits the mast on a keel-stepped mast) and would be bonded to the mast and to a ground plate. These products actually do help and are widely used in the industry:

https://www.polyphaser.com/products/rf-surge-protection

You can add surge protectors to your DC wiring at strategic places. The solar industry sells them prepackaged and ready to wire:

https://www.altestore.com/store/encl...tor-500v-p473/

Or you could make one using off-the-shelf components:

http://www.littelfuse.com/~/media/el...ation_note.pdf

You can clean up DC power considerably with a combination of varistors, small inductors, and medium sized capacitors.

One obvious place would be to add one for the power leads going up the mast. DC power inputs to the navigation and communication electronics would be another.

Data and control connections for a windex and radar would be another area of concern. The safest thing to do is avoid them by using a fiber optic connection or wireless networking. Fiber optic converters for NMEA are not available off the shelf but could be improvised; industrial RS-485 fiber optic "extenders" are readily available that could perhaps be made to work as the NMEA protocol uses RS-485 voltages and signalling. A web search turns up over a dozen.

The main problem is that this stuff isn't packaged and marketed for marine use and there are no widely accepted best practices. There's no real reason that the manufacturers couldn't build this into their products for a few dollars a unit, other than cost.

With a reasonable amount of effort and reasonable budget, it should be possible to protect the electronics to the point where most lightning strikes will no longer destroy all the electronics on the boat. It would be reasonable to expect instead that most of the electronics (over half) would ride through 90% of the hits.

[Pat_D]

Originally Posted by Olddan1943

I have read about folks who, while underway, put a handheld VHF and handheld GPS in the oven with the hopes of isolating them only to bake them the next day.

A good reason to always store stuff in the oven. That way, you always check.

[Cadence]

Originally Posted by Pat_D

A good reason to always store stuff in the oven. That way, you always check.

Broiled GPS and baked Vhf for tonight's dinner. It may work. I don't think it need grounding. It may be better off not grounded.

[CFS Klopas]

Use a microwave. You don't need to preheat it to cook food and it's already designed to shield EM radiation.

[Ken Z]

pelagic, lighting at sea one of my worst concerns ,pirates my second. I have been heavly hit once, airborne 24’ before landing on my butt, lightening strike blasted thru my aluminum drop rudder crossing the gulf stream, to feel like a truck parked on my arm for 4 hrs. no damage, a marine ply glassed boat the air borne , on land, lightly burned the bottom of my feet where there were nails in the sole of my boot were. I think static lighting, the rudder was direct. The other was trying to out a fl sguall, got to dock, tied up, ran for the house, lighting everywhere, hit alum. mast or s s stays dont know, blew a 2x4 hole a few inches above the waterline of a piver tri main hull a ply glassed hull .Got caught in the fl panhandle this summer 14 mi. out, it was a holly molly, so much lighting around, a clear the decks moment, I was amazed I didnt get touched,a hour that every 15 seconds was it s 15 fiberglass hull . I wrap copper ground wire around my stays and turnbuckles and extend 20 “ under water at 4 points of the boat at dock in mansoon weather. I have no answers, lighting is sooooo sporatic just from living in the tropics. good luck , assume nothing , expect less ,leave fear somewhere else, and carry on.....😯🤤😯🤤😀

[GTom]

Originally Posted by Ken Z

I wrap copper ground wire around my stays and turnbuckles and extend 20 “ under water at 4 points of the boat at dock in mansoon weather.

^^, I thought about hanging some 5-6x, Ø10mm copper tubing pieces from metallic parts (radar pole, stays, anchor). Lightning is "AC" and I suspect likes tube conduits better than solid wires/rods, besides a tube has far more contact area with water. My concern is that copper corrodes and over time it becomes a poor lightning catcher.

[puffcard]

The funny thing that happened on my first strike. The hit came in through the VHF antenna the antenna was connected to the radio and after the strike the radio still work, long live ICOM. Everything thing else was toast, handhelds were still also ok.