Lightning Strikes

[Grottie Yachtie]

I was anchored up on a reef a few nights ago with a bank of storm clouds approaching just on dusk, with a lot of lightning in them. I was a bit concerned as I have read reports of boats having holes blown into them and all instruments buggered etc. I have two sets of house batteries and one set of start batteries and I disconnected all of them, just in case. We ended up getting a lot of rain and wind from all directions and thankfully no lightning strikes. in a severe lightning storm what else should be done to keep the vessel a bit safer from a strike. Has anyone had any experience in such storms?
Would appreciate any feedback.

Grottie Yachie

[Wotname]

There is no shortage of lightning related threads on CF

A quick search using the "custom google search" option in the search pull down menu will get you plenty of reading!

[Spindrift NH]

Personally, I don't think I would have disconnected the batteries. I understand the idea that by disconnecting them you remove the potential for lightening to destroy them if you get hit but if you had had to fire up the engine to move quickly you're SOL. With lightning I just cross my fingers, that's about all one can do.
OK, throw any portable electronics in the oven, maybe?

[Cotemar]

Originally Posted by Grottie Yachtie

In a severe lightning storm what else should be done to keep the vessel a bit safer from a strike. Has anyone had any experience in such storms?
Would appreciate any feedback.

Grottie Yachie

For Catamarans there is no direct path to the keels and the keels are fiberglass.

The best way to make a direct connection from the mast to the water is to run 1 or 2 large 4/0 Gauge Battery Cables with and outside diameter of 0.760 inches straight from the base of the mast right into the water below the bridge deck about a foot deep into the ocean.

Catamaran Lightning Cables.

This method gives Lightning a direct path from the top of the mast directly into the ocean ground plane without going throughout your catamarans electrical system to find the ocean ground plane.
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[Grottie Yachtie]

Thanks for the info on lightning strikes. Appreciate it.

Grottie Yachtie

[Sea Scamp]

Hi
We had a bolt of lightning strike the water about 50 to 100m away from us, while sailing past Nelsons Bay last year,
Both Tracey and I just happened to we looking in the right direction at the right time. It wasn't one of those real big thick bolts of lightning that you see, it was pretty thin really, but had a real good crack to it.
Even though it did not hit us, we lost the screen to our chart plotter, it went all blue, never to recover again .

We sailed through some really scary lightning storms coming home from the reef this year, I was sure we were going to get hit, but we never even got close to being hit.
I personally think it doesn't really matter what you do to stop a strike, we just make sure where not leaning or touching anything conductive, like our helm. Auto pilot rides out all lightning storms on Sea Scamp. And I send Tracey down below, no point both us getting fried.

Cheers

[appick]

I agree with the above comment if the electrical charge is enough to jump from cloud to ground, then it is surely enough to jump the gap of your battery switch or just right through the insulation of any of your wiring. I understand feeling the need to do something to be proactive and protect your pricey electronics. However short of a faraday cage you're just running a blender in a lightning storm.

[appick]

Just sit back enjoy the light show and be ready to respond to whatever happens. It's all a big roll of the dice.

[rabbi]

Well I have seen some writing that indicates making such things as cables into the water may actually attract a lightning strike because you are creating a nice path (instead of keeping the boat isolated).
So with hanging wires into the water you may actually increase the risk of a lightning strike, but at the same time you reduce the potential for damage by making it easy for the lightning to jump off your boat. just a thought, no clue which way is better than the other


One thing I do for lightnning preparation is to start the engines. After a lightning strike their electronics could be dead, so impossible to start.
Once running I hope they would cotinue to run even with dead electronics.

Just in case I have to move because of boats dragging anchor

[Cotemar]

Originally Posted by appick

I agree with the above comment if the electrical charge is enough to jump from cloud to ground, then it is surely enough to jump the gap of your battery switch or just right through the insulation of any of your wiring. I understand feeling the need to do something to be proactive and protect your pricey electronics. However short of a Faraday cage you're just running a blender in a lightning storm.

That is exactly what Boeing had to do to create the carbon fiber 787 Dreamliner. They tested the plane for lighting strikes only to find that lightning put holes into the fuselage and would have killed passengers.

Their solution was to put a thin layer of copper mesh under the final coat of paint and it worked perfect. Basically they made a copper mesh Faraday cage.

[Frankly]

One point often muddled about lightning is that the business of attracting a strike is often misunderstood and confusing, however once the strike has attached to a yacht it follows the laws of physics/ electrical engineering quite accurately.

The idea that a voltage large enough to arc through hundreds of yards of sky can still arc over switches/ breakers is not an accurate way to think things through. Once a stroke of lighting current is flowing through your rigging on its way to the sea surface the voltage developed is a function of resistance/ inductance of the electrical path(s). Providing a good low impedance path to send the current surge on its way is always a good policy and can limit other damages. Us sailors with a good aluminum mast just need to finish the job with a short direct connection to the ocean. A poor/ high impedance main path allows the lightning to flow through alternate paths (think 12 VDC system ground) and that can wreak a lot of havoc on anything that has the the letter "e" in it's name. There is also a large EM field surrounding the current path that can induce voltage surges to also do in sensitive electronic components.

Not saying that a good lightning ground system will solve all the ills of a visit from Zeus, just that it ought to be "job one" on any yacht.

[Cotemar]

Most boat surveyors will recommend that you Bonding your masts to keel bolts.

Its been a recommendation for a long time, but most do not do it, as its time and money or they just do not have the skill set to DIY.

The idea of the Lightning grounding system is to divert the lightning current through a "Predetermined Path" so that it does not make its own explosive path through fiberglass, teak, Electric and Electronic systems and crew members.

Catamarans do not have conductive lead keels so they need a Catamaran Lightning cable from the base of the mast straight into the water below the mast.

Good lightning protection systems will be permanently installed and ready for a strike at anytime even when the owners are not on board.
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[J Clark H356]

There is a lot of information in lightning by a University of Florida professor. The short answer is that if your have a path to the water and are properly grounded, the boat has no more change of being involved in a lightning strike than anywhere else in the water. The lightning path is from the boat up, not as most think the cloud down. Lightning strikes where the potential difference is the most. If you are properly grounded, you should have the same potential as the water around you. That doesn't mean you won't get hit, but your odds are rather the same as anywhere else on the water.

[appick]

Originally Posted by Cotemar

That is exactly what Boeing had to do to create the carbon fiber 787 Dreamliner. They tested the plane for lighting strikes only to find that lightning put holes into the fuselage and would have killed passengers.

Their solution was to put a thin layer of copper mesh under the final coat of paint and it worked perfect. Basically they made a copper mesh Faraday cage.

Sweet I'm way underpaid if I'm qualified to be an aeronautical engineer! Lol jk I'm in no way qualified for that. Great info though. I had no idea about the streamline having that but makes sense given there isn't an aluminum frame to somewhat conduct the currents.

[appick]

Originally Posted by rabbi

Well I have seen some writing that indicates making such things as cables into the water may actually attract a lightning strike because you are creating a nice path (instead of keeping the boat isolated).
So with hanging wires into the water you may actually increase the risk of a lightning strike, but at the same time you reduce the potential for damage by making it easy for the lightning to jump off your boat. just a thought, no clue which way is better than the other


One thing I do for lightnning preparation is to start the engines. After a lightning strike their electronics could be dead, so impossible to start.
Once running I hope they would cotinue to run even with dead electronics.

Just in case I have to move because of boats dragging anchor

Good thought and makes sense.