Lightning

[Canibul]

I was grounded briefly when I was 14. I didn't like it.

[belizesailor]

Originally Posted by Nicholson58

......

I wonder if total air gap disconnect including the ground/neutral and antennas would go far to prevent damage? This would be about the same as an uninstalled device lying free on the table. I think I will be buying a few switches.

Physically disconnecting makes a path less conductive and thus in theory less likey. This may help reduce physical damage, but even a nearby strike with no physical hit to your boat can fry electronics, even if completely disconnected, due to huge electromagnetic pulse energy. I've had electronics effected by nearby strikes with symptoms ranging from DOA to just having memory scrambled (only a reset required).

Lightening will blow thru solid fiberglass to find a path to ground so a very small air gap is not going to stop it if it decides to go that way (after all it jumped thousands of feet of air to get to ground in the first place).

I think an electronics center with a built in Faraday Cage would be a cool feature. All electronics mounted inside, a metal door that closes over the face of all components to make the box complete when not in use. And some clever/convenient means of islolating or disconnecting all the wires leading to the devices. More convenient and quicker than removing electronics and putting them in the oven. Just close the door and disconnect when away from the boat or when lightening threatens.

[sy_gilana]

Hey I can sell you a lightning protection device, its a little black box that you fix to the neg system. It costs $5000,00 and has a money back guarantee, if you do get hit, you get your money back.

[colemj]

The nice thing about NMEA2000 is that the power and data are all on the same cable and networked - disconnect the power tap connecter and all the instruments are "just lying on the table". For more security, you can also disconnect the masthead instrument(s) cable.

Doesn't prevent EMP damage, but it is very easy to isolate them from direct damage.

Mark

[onestepcsy37]

Originally Posted by colemj

Doesn't the CSY37 have a keel-stepped mast? If so, you are grounded by default. I don't understand why you worry about a strike finding its way to a thruhull and blowing it out, while simultaneously being happy not to be grounded? The purpose of grounding is to provide a more favorable path for the lightning than a thruhull.

Mark

The mast actually sits on a heavily constructed base, a few feet from the keel.

I'm no Steinmetz, so feel free to correct me, but I always thought that "grounding" meant connecting all throughhulls, the mast, the engine/drive train/shaft, etc., together with some sort of ground wire. If true, then wouldn't lightning striking the mast travel through the ground wire to the thruhulls?

Alternatively, I have heard that you can clamp one end of a long jumper cable to the mast and toss the other end overboard. Comments?

[a64pilot]

Originally Posted by onestepcsy37

Alternatively, I have heard that you can clamp one end of a long jumper cable to the mast and toss the other end overboard. Comments?

I do that with about eight feet of 5/16 316 chain I used to use to "tie" into wreck for diving, I hook the chain to a chainplate assuming the standing rigging would be the conductor.
More hope than science as I have seen aircraft tied down with eight chains get struck with lightning, you would think the current would go through the chains, maybe some did, but some went out the pitot tubes blowing holes in the covers, and Lord knows where else.

[CarlF]

Three boats had their electronics fried in our marina last year when a boat was hit and the lightening surge went through the shore power cables to other boats (or so it was described to me).

Is there any sort of surge protector that could be put on the shore power inlet to protect against this?

[HappyMdRSailor]

Originally Posted by belizesailor

I think an electronics center with a built in Faraday Cage would be a cool feature. All electronics mounted inside, a metal door that closes over the face of all components to make the box complete when not in use. And some clever/convenient means of islolating or disconnecting all the wires leading to the devices. More convenient and quicker than removing electronics and putting them in the oven. Just close the door and disconnect when away from the boat or when lightening threatens.

That my friend is a SLICK IDEA!

I'm a test lab guy for furniture, and we see flipper door cabinets for office panel systems all of the time... Door lifts and slides on top of the cabinet. Mount one of these in a nav station, mount your electronics in it... Make a couple of disconnect plugs for the whole box... Flashee come... shut the door... Pull the plugs...

Plus... Now you have a locking panel to cover your stuff....

[Lake-Effect]

A friend of mine runs a small marine electrical service. A strike on one boat at a yacht club caused enough damage to that and adjacent boats that he bought a new van.

Lightning causes a stupendously-big instantaneous current, and a chain, electrically-speaking is a series of lousy connections. I can't remember the source, but I believe I read of chains exploding in a direct hit.

[belizesailor]

Originally Posted by HappyMdRSailor

That my friend is a SLICK IDEA!

I'm a test lab guy for furniture, and we see flipper door cabinets for office panel systems all of the time... Door lifts and slides on top of the cabinet. Mount one of these in a nav station, mount your electronics in it... Make a couple of disconnect plugs for the whole box... Flashee come... shut the door... Pull the plugs...

Plus... Now you have a locking panel to cover your stuff....

Yes, similar idea, but something that won't corrode. Run power via single large gauge +/- cables to bus bars inside to which gear attaches then you just need a dual pole breaker for the power and a few quick disconnects for antennas...to make it quick and easy.

[belizesailor]

Originally Posted by CarlF

Three boats had their electronics fried in our marina last year when a boat was hit and the lightening surge went through the shore power cables to other boats (or so it was described to me).

Is there any sort of surge protector that could be put on the shore power inlet to protect against this?

This is one reason I don't like leaving shore power connected in marinas. I disconnect when not aboard or when lightening threatens.

Had control board on an AC unit taken out this way once. Lightening started, I got up to disconnect....BOOM....not quick enough! Tripped all breakers on the panel but only damage was AC control board.

[colemj]

Originally Posted by HappyMdRSailor

I'm a test lab guy for furniture

My mental picture for this statement is a guy in a lazyboy with a beer watching television…

Mark

[colemj]

Originally Posted by onestepcsy37

I always thought that "grounding" meant connecting all throughhulls, the mast, the engine/drive train/shaft, etc., together with some sort of ground wire. If true, then wouldn't lightning striking the mast travel through the ground wire to the thruhulls?

Alternatively, I have heard that you can clamp one end of a long jumper cable to the mast and toss the other end overboard. Comments?

Originally Posted by a64pilot

I do that with about eight feet of 5/16 316 chain I used to use to "tie" into wreck for diving, I hook the chain to a chainplate assuming the standing rigging would be the conductor.

Originally Posted by CarlF

Is there any sort of surge protector that could be put on the shore power inlet to protect against this?

Connecting all thruhulls, etc together is better known as bonding them, and is done for corrosion reasons - not lightning. Grounding is providing a specific path for lighting to (hopefully) follow. Even if your thruhulls are bonded, you should still have a lightning ground to direct a strike to water. Ideally, the bonding and grounding circuits will be separate.

A jumper cable connected to the mast and put overboard helps, but only if the connection is a good one (a true solid high contact area clamp or screwed on plate and not an alligator clip) and the end has enough surface edge area (meaning some type of electrode, and not just the end of the wire). Better would be to connect your mast to your keel with a stout jumper.

Chain connected to a shroud or chainplate is a poor idea. First, the large aluminum mast itself is a straight, high-current conductor to ground - or close enough to ground to be the same thing - and the small stainless shroud would be a secondary path at best. Second, the chain itself is a poor conductor because the contact areas are very small between links, are in constant movement, and may not even be disconnected at any given time.

You can put surge protectors on your main AC and DC panel feeds, as well as on individual circuits. These are solid state devices that work well at clamping and shorting high over-current and over-voltages fast enough to prevent damage to equipment. Your house probably has one on its main panel, and they are common equipment in computer rooms, radio rooms, etc. They cost a bit, require thoughtful installation and won't help with EMP problems. Whether they are worthwhile is a personal decision.

Mark

[belizesailor]

Speaking of lightening...its crackling pretty good right now as I sit on the hard...may run a cable down to the jack stands! There is a very tall radio tower not far from me...I hope the lightening prefers that.

A big Priviledge 75, tallest mast in the marina, got whacked recently. Carbon fiber does not respond well to big amperage....that's going to be a huge repair bill...electronics fried too.

Mark, want me to check anything on Reach?

[onestepcsy37]

Originally Posted by colemj

Connecting all thruhulls, etc together is better known as bonding them, and is done for corrosion reasons - not lightning. Grounding is providing a specific path for lighting to (hopefully) follow. Even if your thruhulls are bonded, you should still have a lightning ground to direct a strike to water. Ideally, the bonding and grounding circuits will be separate.

Thanks for the explanation. Now I know that I am neither bonded OR grounded. This boat hasn't been bonded in its 35 year life so I think I will just keep it that way. The bottom of the mast sits on a rather substantial base, about 3 feet from the 8000 lb lead keel, which is completely encapsulated in fiberglass. I could run a bigass cable or grounding strap between the two. Something to think about.