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Old 23-07-2007, 10:40   #1
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lightning storms

I’d like to solicit some opinions about how to handle lightning storms in various circumstances. I’ve got a lot of experience on daysailers, where you just get off the water, but not much cruising experience (in the process of changing that now…). In particular, I’d like to know what people do in situations such as when you are

1) in a bay or inlet, with no opportunity to get off the boat, and possibly, no opportunity to anchor (coral, etc,);

2) near shore, especially too near to heave to in a longer storm, but not near enough to anchor (or coral bottom, etc);

3) offshore with plenty of room to maneuver.

Do you try to keep your hands off the wheel (by using the lock or the autopilot). Do you turn all the nav systems off? What if you have to steer, such as in the first two cases?

Thanks for your input. Pete
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Old 23-07-2007, 11:48   #2
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I just took a hit over the weekend. Run against the storm direction if you can, the idea being to get through it quickly. If the wind is 50-60 knots in microcells that won't be possible. In that case, hang on to the wheel steering to keep your boat on the blue wet stuff and keep your head down.

That other thread is at:

was hit by lightning today
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Old 23-07-2007, 14:20   #3
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yep...

Hi Rick: yep, I had already read your story a few days ago. Prompted me to ask my question. Thanks for your input, and congratulations on getting through it unscathed!!! Thanks for the advice as well. Best, Pete
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Old 23-07-2007, 20:11   #4
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I would agree with Rick. Get the sails down, the engine running, and tie eveything down and get through it as fast as you can. When you start to see it coming it's time to act. You can't do any of this if you wait for it to hit you. Radar can help you see it and better judge the distance. Main thing is don't wait too long to prepare.
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Old 28-07-2007, 12:59   #5
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Lightning dissipation/diversion system for a sailboat?

This is an interesting topic, but I could not find a consensus on what to use for lightning protection – except prayer. Because this approach risks the development of TMJ during a severe storm, I plan to try something simple and inexpensive. The direct, low resistance path includes no connections or bends which would add resistance and heat up. The hope is to keep most lightning out of the boat, not just give it a safer route through the boat via the mast. This would also keep it further away from the electrical/electronic systems and reduce field effects.

There is a great deal that we do not know about lightning and lightning protection.
The “non-conventional” systems, based on “lightning elimination”, or “early streamer emission” have not demonstrated clear superiority to the conventional system; at least not enough to create a consensus. Whether the rod tip is a sphere, pointed, rounded, a brush, or any combination of these, may not make a huge difference, since the definitive study has not yet been done. Controlled studies are difficult, and the favorable reports are something like; “it works for my customers”, from groups with a financial bias.

There is also a great deal we do know.
A “conventional” system consists of a rod (or air terminal) with a conductor to ground. This system has been quite effective on land for centuries.
The “rolling sphere” theory seems to have a reasonable consensus, as does the speed of sound, whereby your can calculate the distance from the lightning at 5 seconds per mile when hearing the thunder. We also know that you can’t predict where or when lightning will strike, so any lightning protection should be set up at the onset of the storm, or sooner. That is - long before the first close hit. You don’t want to be handling a hoisted copper wire then, even if it is insulated.

The plan.
Hoist half inch PVC pipe, 8-10 ft long, with a halyard (attached near the bottom of the pipe, and a rolling hitch 3-5 ft above the attachment), so that the top of the pipe is near the top of the antenna. 8 G (or larger) stranded, insulated copper cable (about $0.62 per foot at Home Depot, or $150 for 100 ft of tinned marine grade, from Boater’s World) runs through it, ending at least 12 inches above the antennae. The top 12 inches of insulation are removed, and the bare copper wire strands are possibly splayed open (or pointed or rounded). For a catamaran, stretch the wire almost straight to the bow netting, away from metal, through a small piece PVC pipe and into the water. Remove insulation near the water level and splay open at least three feet of the wire in the water. The wire is held in place in the upper PVC tube by a wad of electrical tape on the wire. For a monohull, lead the wire through a short piece of PVC pipe, over the lifelines. Choose the side that has the least electronics to minimize any field effect.

The PVC will add rigidity to allow the wire to be hoisted above the antennae, and extra insulation where the wire contacts other surfaces.

If the wire is left in the water for long periods of time, it should be cleaned periodically. If left in the water for prolonged periods, consider the tinned copper wire. Also, rinse any salt off the wire and PVC pipe so it doesn’t become a conductor.

If your mast height can navigate the ICW, this whole system should cost you less than $50. (Of course you could pay more if you feel that will help it work better.) If your mast is much taller, consider 6 G wire (or larger). Once you have determined where to attach the halyard, and have put the tape on the wire, it should only take a few minutes to set up. This process will be more difficult when sailing.

Of course, I would keep this completely separate from the bonding system.

I am not trying to sell anything, and I would appreciate suggestions about this simple, inexpensive approach. I am not a lightning expert, but have put considerable thought into the problem after reviewing some of the literature.
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Old 28-07-2007, 22:40   #6
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I'm not sure I would anchor

It would seem one would be creating just the inviroment the lighting wants, a path to the earth. I guess, if your chain was hooked to a lighting rod......
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Old 28-07-2007, 23:14   #7
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When sailing offshore with thunderstorms in the area, we use our radar to tell whether the cumulonimbus cloud is going to come down on us. We put an estimated bearing line on the cloud, and if it comes down the estimated bearing line, we change course and turn on our engine to motorsail away from the ill-mannered cloud. At night, doing this is harder because we can't always see the offending cumulonimbus cloud, and that makes it harder to follow the cloud on radar. Most of the time, we have been able to dodge the clouds, but sometimes we have had to motor full throttle for up to an hour to get away from large menacing clouds that are heading our direction.

When at anchor, we are at the mercy of the lightning gods. If it's a bad storm, we disconnect as many electronics as possible. We stay away from metallic objects like the steering wheel, and stay inside our farraday cage - meaning try to have as much metal between us and the lightning as possible in case there is a strike. We don't wander around on deck in lightning storms. If we are at the mast, we don't dilly dally - we drop the sail into the lazy jacks and get back into the relative safety of the farrady cage created by the metal components of our boat.

I think it is mostly a matter of luck. When we were in Singapore, there were five yachts struck by lightning during the first week that we were there. That made us a bit nervous.

We read in a cruising guide that one yacht out of a thousand gets struck each year in the Bahamas. That doesn't surprise me, because nearly every afternoon that I was in the Bahamas, there was an afternoon thunderstorm.
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Old 29-07-2007, 21:25   #8
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We just had a nasty one here tonight, actually ended up with a little tornado action. Anyhow had some odd items burn up, first was a 12vdc flourescent light, second was the CD player, which blew the breaker and stunk like electronics do when the entrapped smoke is released. Odd though neither were on at the time. I am just hoping nothing major got fried, i haven't checked the electronics yet.
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Old 30-07-2007, 17:20   #9
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Since lightning strikes actually "Start" from the ground not from the air (ion charge path)... moving the ground higher by providing an excellent path would not be in your best interest unless your intent is to cause any near by strikes to hit your target. Most systems on a boat will have a spark gap to reduce the chance of making the high point more attractive but if the strike occurs it will jump the gap.

The most effective protective measure is to avoid the problem, the next is probably to protect yourself with a Faraday shield type of environment ( like an umbrella) NOT a primary point to have strikes attracted to. With an effective Faraday Shield a strike would follow the Shields elements leaving the areas protected by the umbrella effect more protected.

This is what is used in very sensitive applications, like explosive/ ordnance factories and even many space vehicle applications while on the ground. You would never want to have a lightning rod directly tied to either of those but have a shield. A reasonable effective shield can incorporate the standing rigging of most sail boats.... the poor power boats have far less ability for using the Faraday Shield concepts.

BTW we typically evacuated the ordnance facility when lightning was within 2 miles as determined by a strike recorder.

It would be unrealistic to assume the power of a lightning strike can be fully directed by a copper cable when other nearby items such as standing rigging and other equipment are within a few yards. Lightning is not a small current flow event... in a storm with salt spray and water a single path is totally unrealistic. The Faraday Shield accomplishes part of its task in providing the multi point of discharge but only when needed.
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Old 30-07-2007, 17:34   #10
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I would certainly agree that Faraday Shield's are the textbook answer to a lightning strike. May I ask if you've been onboard during a lightning strike? In a catamaran the fastest way to ground was through my twin drive shafts into the water. It turns out that I had built in lightning protection all along.

was hit by lightning today
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Old 30-07-2007, 17:57   #11
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I've not been hit but have been within under 100 feet of a strike several times.... that reaffirmed my belief I didn't want something saying " hit me" sticking in the air. The hair standing, numb feeling and metallic taste in the mouth is as close as I ever hope to get.

I did work in a ordnance facility in Central Florida just across the Hwy from Kennedy Space Center where we did receive several hits over my 13 years. The Faraday Shield system prevented/ reduced the potentially volatile situations had a direct strike occurred on one of the factory buildings or bunkers protected by the shields.

These same systems are used at other sensitive facilities over the entire world and I have seen them from Norway to Turkey and a couple of locations in the Pacific. I think it is rather universal in applications where maximum protection is required... of course they still evacuate when storms approach... nothing dealing with nature is fool proof.

However attracting it isn't a great thing unless it is part of the overall Shield. A Mask with a ground potential at its top isn't something I would desire. As part of an overall shield with spark gaps it is useful but you would not want to increase its height even a inch.
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Old 30-07-2007, 18:23   #12
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I was hit while motoring, just south of the Pineda Causeway. An area it sounds like you might be familar with.

The storm rolled in within minutes and there was no place to go, so I would imagine that a 40 something foot mast would pretty much have a "hit me" sign on it.
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Old 30-07-2007, 23:38   #13
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Quote:
Originally Posted by Reality Check
I did work in a ordnance facility in Central Florida just across the Hwy from Kennedy Space Center where we did receive several hits over my 13 years. The Faraday Shield system prevented/ reduced the potentially volatile situations had a direct strike occurred on one of the factory buildings or bunkers protected by the shields.
How fine was the mesh in the shield? Would it be practical to reproduce that structure in a boat?
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Old 31-07-2007, 08:47   #14
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Quote:
Originally Posted by rickm505
I was hit while motoring, just south of the Pineda Causeway. An area it sounds like you might be familar with.

The storm rolled in within minutes and there was no place to go, so I would imagine that a 40 something foot mast would pretty much have a "hit me" sign on it.
You are correct! between Pineda and 520 Causways... both in the Banana and ICW. Great sailing area, wide and long but those summer storm can pop up and role in before you can do anything. Twice I've been in microburst in that area where the ICW is widest just south of 520 where the wave action went from under a foot to more than 5 in about 5 minutes but it only lasted about 5 minutes. Was in a 26' sloop and thought I was on a mustang. First time I dropped sail and tried to motor with a 4hp Volvo inboard sail drive... into it but it slid me back but I was some distance from either shore. Second time I was anchored and that was worst as far as having to hunker down below and bounce from the settee to the cabin liner every few seconds just for fun...

COOT: The do not use Mesh... a series of elevated lines ( some 25 feet or so) that are spaced some 10 to 15 feet apart run over and adjacent to areas being protected. Each pole has a ground strap but in some these are spark gapped, but in others a hard ground is used. I have seen systems where either positive or negative potentials are placed on the shields Lots of different views on this type land protection system but on a boat in salt water the standing rigging provide the protection but spark gaps are used to avoid bringing the ground level to the top of mask and sending a "HIT ME" to the area storms.
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Old 31-07-2007, 12:11   #15
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Originally Posted by Reality Check
They do not use Mesh... a series of elevated lines ( some 25 feet or so) that are spaced some 10 to 15 feet apart run over and adjacent to areas being protected. Each pole has a ground strap but in some these are spark gapped, but in others a hard ground is used. I have seen systems where either positive or negative potentials are placed on the shields Lots of different views on this type land protection system but on a boat in salt water the standing rigging provide the protection but spark gaps are used to avoid bringing the ground level to the top of mast and sending a "HIT ME" to the area storms.
Isolating Spark Gaps electrically connect the grounds, at higher lightning potentials, that are otherwise isolated*.

* The lightning down conductor may be isolated (at lower voltages, under several hundred volts) in order to reduce galvanic corrosion and eliminate electrolysis.
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