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Hit by lightening - electronics

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Mike Rauh
Deckhand

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11 Posts

Initially Posted - 07/27/2008 : 13:22:44

I boarded my fixed-keel 1980 C25 with some friends and began getting ready to sail. One friend who was down below came up with the end of the master switch in his hand. "It just came out in my hand." I thought this was unlikely and went down to check out the electrical panel. What I found was painful to see, the master switch was actually melted!

I checked around and found the bilge pump had the cover blown off and was partially melted. The radio was shot, even when I bypassed all switches and ran a temporary lead from the battery to any component. My depth and speed guages were also zapped along with my electric start Nissan 4-stroke 9.8 motor.

At the top of the mast I saw my windex vane and antenna were gone too. It's so depressing, over the past 3-years I've put in all new plumbing and wiring. All the electronics and the motor were under 3-years old.

Before I start to replace everything I'll call the insurance company (Boat US) and see if I'm covered or if it's an "act of God."

Prior to installing new electronics I'm interested in getting some collective wisdom on improving the electrical system.

Should I install some sort of fuse arrangement or would lightening just jump the fuse and melt everything again. I've searched the site for information on grounding pros and cons. Do any of you know of any recent information that would give me reason to ground the mast to the keel?

In this topic I'm looking for electrical know-how; I'll start a second topic on lightening and physical impacts. Thanks for any assistance you provide.

For the record, my boat is on a 350-pound mooring at a yacht club where it's surrounded by other boats with taller masts. One of them was also struck the during the same storm. The boat is in salt water (the Long Island Sound, NY). My battery still puts out 12.76 volts and the cabin lights still work. The outboard will start by pulling the starter rope but will not start electrically - even after replacing the 20-amp fuse in the motor it just blows when I connect the battery.

1980 C-25 TR/FK
Capt. Mike
City Island, NY

Edited by - on

Dave5041
Former Mainsheet Editor

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USA
3758 Posts

Response Posted - 07/27/2008 : 17:08:37

Be assured that if lightning can jump several miles of air, a fuse won't help. For protection, search for a recent thread discussing lightning protection. It has some good references. I am of the mind that grounding, but with an air gap, is probably best.

Edited by - on

redeye
Master Marine Consultant

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3477 Posts

Response Posted - 07/28/2008 : 08:26:20

It seems it would be best to try to add grounding to mast and reduce conductance from mast to electrical panel.

I might add a big wire from the mast to the keel and wire the mast lights with 18g and fuse both the hot and ground.

A perko battery selector switch might help to isolate the engine.

I'm afraid I agree with others in that is seems the fuses don't help with lightening. I'd like to hear what has happened to others in this case.

Sorry to hear of your loss, and such a strange way to have it happen.

On my boats I disconnect the radio and depth finder each time I leave.

It gives me a chance to rub some oil on the connections.

Edited by - on

Stardog
Captain

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USA
319 Posts

Response Posted - 07/28/2008 : 13:07:01

I read a lot of research on lightning, there isn't much you can do unless you install a lightning protect system. Research shows that even with a lightning protection system you have a 50/50 chance of having severe damage. Such systems are very expensive and use special metals bonded to your mast and other parts of your boat to conduct the electrical strike, even then the best you can really hope for is that the lightning will pass to the water through your keel without blowing holes in your hull. I used to always go with the old "tried and true" method of hanging a chain into the water from one of my shrouds, but reseach shows that the lighting will not take that detour, it will go directly through the cabin top and bulkheads to the water. On the bright side, according to the odds you're probably never going to be hit again.

Edited by - on

stampeder
Master Marine Consultant

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1608 Posts

Response Posted - 07/28/2008 : 13:25:43

IMHO - there is not much you can do on a 25 ft boat. That said, the best protection for a 25' boat is to be close to bigger boats and to be ashore when lightening strikes.

The challenge with Lightening is that it is High Amperage, in other words, electrity moving at high speed - and it is the high speed that does the damage because the voltage itself is rarely great enough to do much harm. You were probably hit by a fairly small bolt of lightening, or were hit by lightening that partially dissipated itself on another boat.

A chain on a shroud would likely have helped dissipate as it would have increased the load. But again, lightening is moving with such force that it wants to continue moving forward like a bullet once it makes contact with something.
I'm in a very high lightening area. What I do is get off the boat, and I disconnect everything, especially the batteries.
In previous threads I have claimed that I prefer simplicity and don't have a lot of gadgets on my boat - one of the reasons is lightening frequency at my lake. I also sail on the west coast on Vancouver Island which is conversely, an area that has the lowest number of lightening strikes in Canada.

Edited by - on

Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts

Response Posted - 07/28/2008 : 14:58:35

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by stampeder
 ...the voltage itself is rarely great enough to do much harm.
<hr height="1" noshade id="quote"></blockquote id="quote">Yup--only a few hundred thousand up to a couple of million volts... But it's true that amperage is the issue-- 1/50 of an amp through your chest cavity will likely kill you whether it's at 12 or 1200 volts. Lightning is generally of the magnitude of 50,000 amps per strike. The greater the distance and/or the drier the air, the higher the voltage has to be (~30,000 volts per inch at 0% humidity). The physical shock wave from exploding moisture and the magnetic impulse from the bolt itself can cause damage to things that were not actually "hit". The "speed" is the same as that of the spark you generate by shuffling on the carpet and then touching your little sister, but that spark has extremely low amperage--just "empty volts". I think I heard that an electrical discharge through air averages something like 50,000 miles per second--the rate at which the charge moves from molecule to molecule.

Well, there's the bell.

Edited by - Dave Bristle on 07/28/2008 16:09:40

stampeder
Master Marine Consultant

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1608 Posts

Response Posted - 07/28/2008 : 15:33:48

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Yup--only a few hundred thousand up to a couple of million volts...<hr height="1" noshade id="quote"></blockquote id="quote">
Of course, you are right Herr Doctor. However, it is the amperage that does the killing (and sinking and melting). If 100,000 volts had hit his boat at 100,000 amps, he would have found the pieces of his boat on the bottom of the lake. It is the individual discharges called strokes or flashes that combined, look to the naked eye like a lightening bolt, that most likely hit his boat. An individual discharge (flash/stroke) would IMHO, have hit at high amperage, relatively low voltage.
A single lightening bolt can have a voltage (potential difference) of several hundred million volts. It is a continuing current from a full on lightening bolt that would start a fire, not a single episodic discharge.

Edited by - on

Mike Rauh
Deckhand

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11 Posts

Response Posted - 07/28/2008 : 19:32:05

Thanks for the discussion and reference to earlier association information.

I also went to the Boat US website and then to their insurance section where I located the "Seaworthy" magazine archive articles. There was a good article about lightening which covered many of the points you brought up.

I've called the Boat US insurance line and opened a claim. So far they've been very helpful. I'll open a topic about my expereince with them as my claim moves along.

Thanks for responses.

Edited by - on

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