lightning

[Cruisingdad]

Now SD, don't get technical.

The point of a dissipator is the following: Out in the ocean, the lightning finds an easier path away from you... likely one of those mountainous swells.

In the marina: The lightning strikes your buddies boat - you know, the whole cone of uncertainty!!

Which is why, whenever I am in a new anchorage and a storm approaches, I find the lonely Sea Ray, drop his anchor in the water, and raise his VHF Antennae. Does it work...? I will never tell.

[hellosailor]

"Does anyone know where to look for a real scientific answer???"

Sure. Any plasma physicist can tell you that when there's a kajillion volts and amps flowing around, it is going to go anywhere it damn well pleases. You can influence the path, sometimes change the odds a little, but for hard answers and guarantees? Uh-uh!

Short of that, "modern" science still doesn't have definite answers for how to keep lightning away. That's why NASA, with their lightning rod on the launch tower, still went exploring to see what might have fried when the lightning rod "took" a big strike this weekend. They just don't know. The final decision was based on a very low-tech inspection routine: The techs SMELLED something burnt.

All the high tech science, and the Mark1Nose was still what they chose.<G>

[marinedtcomRob]

OK, so I've been hit twice so far. Once on my grounded Little Harbor 38 and once on my Grady White 23 motorboat which I grounded to beat the band because I'm paranoid. The sailboat got hit at Three Mile Inlet (Long Island) and the Grady got hit at Cape Lookout, NC. The Grady was nestled in among about 15 sailboats with much taller masts than my 20' outriggers. So, if I had no grounding might I have not been hit? I'd guess that would be likely. On the other hand, a few weeks before the Grady got hit an ungrounded sailboat got hit. The strike went down the shrouds to the chain plates, then blew holes out the bottom of the boat below / near the water line. The boat sunk quickly. So after two strikes, while I hope the third is NOT the one that kills me, I'll still take my chances being grounded. At least I have an idea the of the path the lightning will take. In neither of our strikes did we experience any significant damage. I had disconnected all the electronics I could and lost only a small electronic module on the Grady engine and a Heart Pathmaker on the sailboat.

[Cruisingdad]

There are inexpensive ways to ground your boat. A very, very accomplished sailor-friend of mine grew up in the islands. In all honesty, they would wrap the anchor chain around the shrouds and let it drape just off the boat.

Thus, if you are really that worried about it, you can just do that. Is it worth it... well, that is a question we each must answer...

I have read about the dissipators and the science seems logical. Of course, I am a biochemist, not a physicist. However, it is not 100%. When I said earlier that you keep your boat from being hit so it hits your buddies boat... well, that is not far from the truth. And the trick about lightning, as MANY OF US HAVE SEEN: IT DOES NOT HAVE TO HIT YOUR BOAT. If it hits anywhere close to you, you can kiss your electronics goodbye. Thus, here is a good reason to: ALWAYS CARRY HANDHELD BACKUPS. They are not that expensive, and might just save your life.

[hellosailor]

As undertand it, the problem with grounding everything on the boat is that while grounding provides a more direct path for lightning to "come down", and in theory come down directly without flashing over into everything including the crew, that same grounsing also ensures that if there is a charge building up in your area---you are now elevating that charge and putting the ionic path higher into the air, so it is closer to the cloud charge and more likely to be hit. Oopsie.

I'd still rather have the direct path for the strike to come burning down (or up, since ground to cloud strikes are also normal) than have it take a random walk all over the boat.

Safest thing to do is just sink the boat, and dry it out afterwards. Probably almost as good to careen it way over, but for some reason, not very popular. <G>

[sailingdog]

Originally Posted by Cruisingdad

There are inexpensive ways to ground your boat. A very, very accomplished sailor-friend of mine grew up in the islands. In all honesty, they would wrap the anchor chain around the shrouds and let it drape just off the boat.

Thus, if you are really that worried about it, you can just do that. Is it worth it... well, that is a question we each must answer...

I have read about the dissipators and the science seems logical. Of course, I am a biochemist, not a physicist. However, it is not 100%. When I said earlier that you keep your boat from being hit so it hits your buddies boat... well, that is not far from the truth. And the trick about lightning, as MANY OF US HAVE SEEN: IT DOES NOT HAVE TO HIT YOUR BOAT. If it hits anywhere close to you, you can kiss your electronics goodbye. Thus, here is a good reason to: ALWAYS CARRY HANDHELD BACKUPS. They are not that expensive, and might just save your life.

A couple of points...wrapping anchor chain around the shrouds and then dropping it into the water doesn't really help as the lightning will often take the straightest path into the water...at the voltage it is at, the slight resistance caused by an inch or so of fiberglass is not really a problem.

Also, handheld backups of electronics will also get fried on a boat that is hit by lightning unless you store them in a faraday cage. Best simple way to do this is drop them into the unused pressure cooker and seal the top. That way any EMP from the lightning bolt won't fry the handhelds...

[sailingdog]

I just had one more question...Why is this in the HerSailNet forum???

[Cruisingdad]

SD,

Why is this in the sailnet forum? I cannot say.

I agree, you have to protect the handhelds or they will get fried too. I have heard the pressure cooker thing. I always kept mine in a glass jar with clamp lid. I have not done a full scientific research to determine the valididty of whether this will truly work in a lightning strike... but I did live aboard in S Florida (lightning capitol of the country) and they always worked. As far as they pressure cooker, Fooogeettaabbouuut iittt! Love my wife. She is the best and loves boating more than me. However, you really think she would remember to always put those things back in the pressure cooker after dinner?? I don't think so. I would sometimes question whether she would remember to even take them out first!!

As far as the anchor/shrouds - I cannot attest to whether it works. Lightning/electricity will take the easiest path to ground. If the resistance is less going down the shrouds, chain, then water... well, it would seem logical that it would take that path. Fiberglass is not a good conductor (thus the damage via lightning). Now, if your boat WAS grounded, it would seem that tossing over the anchor chain would not make a lot of difference.

You are right though, a gap in the chain could very well change its path. I did not say I did it... but he did and a lot of the locals.

[hellosailor]

CD-
A glass jar won't help. A Faraday cage (all metal enclosure with no gaps or breaks) works by carrying the electrical charge on the outer skin and not allowing it to enter the "cage". Metal screening can work, if the mesh it tight enough, but solid sheet metal is recommended for high power like lightning. That isn't always enough thought, there is some question of whether *magnetic* eddy currents can still be induced into any circuitry inside the cage (like a transformer) causing the contents to get disrupted anyway. Still, the Faraday cage is your best bet and protects against significant problems.

It is OLD technology, but still state of the art for protecting facilities from EMP associated with nuclear attacks. Yes, they do whole rooms and bunkers with all metal seals on everything. (Steel yacht anyone?<G>)

The pressure cooker would *not* make a good Faraday cage unless you replaced the rubber lid gasket with something like metal mesh, or there was a good metal-to-metal contact between the lid and the pot. Any break in the metal-to-metal, and the cage doesn't work.

Folks have also suggested using an oven (which can be a problem if you forget to take the goodies OUT, no joke) or a breadbox, or any cabinet or locker (preferably small) fully lined with metal mesh or metal window screening, copper roof flashing, etc.

If your ToDo list is short enough, or you're in lightning country, those might be things to think about.

The mason jar will certainly help keep your VHF dry and floating if the blast sinks the boat though.<G>

[Cruisingdad]

My old man mentioned another thought to me to protect it: He said wrap it in lead foil??

I thought about that... now why wouldn't that work?? Course, I asked him where I am supposed to get lead foil. He suggested an electronics store. I never know if he is pulling my leg or not.

I have to admit, I did well in physics in college, but it never was my favorite subject. No good looking teachers. In fact, I think the whole floor was devoid of human life. Damn I should have been a business major. Oh well. Point being, I am fairly uneducated in it and should read-up.

Lead foil anyone?? Is that made by Reynolds Wrap??