Lightning, and what to do about it

[barnakiel]

One thing possibly deserving mention here (since we are at #76) is how challenging isolated lightning/storm clouds are to track.


Most of the time these are not sailing downwind (thinking about the wind direction as observed on the boat). Much more often the cloud will travel at an angle. Driven by winds higher up.



After many years of observation, and much note taking, I think I have discovered what kind of angle it is!


barnakiel

[nortonscove]

I don't give it much thought here in Newfoundland. Almost all of the lightening I've ever seen has been on the land. The water is much too cold to give it my attention.

[barnakiel]

Over open water and offshore I think we met claps on two occasions:


- on the front line ( a cold one),
- on a fuzzy front line (e.g ITCZ),


The ITCZ ones can be really funny to watch as they can be solitary white hell sky towers in otherwise clear sky. When these explode at night the blob of the cloud becomes one hell of a softbox. VERY SCARY.


The former ones create a lot of cloud-to-cloud action. The latter ones tend to hit water with massive sound and otherwise FX.


b.

[transmitterdan]

Grounding a mast has little relation to the probability of a lightning strike. Think it through and you can see why. The lightning has to jump up to a mile or so through the air. The gap between the mast base and the ocean (feet) is tiny by comparison. So as far as static charges are concerned all masts are “grounded”.

But it does help if the current has a low impedance path from the mast to the ocean. Especially so if that path does not include the power wiring and electronics on the boat. So connecting the mast with short heavy wire or flat strips to an external metal plate in the water helps reduce the risk of electrical damage. Same logic applies to shrouds and stays.

You can’t control the current from a lightning strike. You can only give it some “hints”.

[swordds]

Thank you for trying to inform this group of something someone might find interesting. Wrong group for that though. These folks are only interested in hearing their own opinions and ridiculing someone else’s.

[GarthGregory]

I have sailed in a severe storm , with lightning strikes hitting the sea all around the yacht , all this with a 70 foot mast up in the air , not a touch . I wonder if it might help to hang my anchor / chain in the sea and hopefully conduct a strike from the mast down the forestay and chain directly into the sea ?

[rlh1246]

You can't stop lightning from striking, but you can protect your boat and crew from damage once you have been struck. I have been hit once on land and I can tell you it hurts like hell. I was lucky with no residual damage other than a twitch and watching the sky. My boat was also hit one time and thanks to an agressive dissipation system that I designed and installed, once again there was no damage to boat, electronics or crew. You can protect yourself, but not from being struck.

[SSgtPitt]

After reading the thousands of lightning posts on CF, we determined we’d just stand in the middle of the boat and touch nothing metal.

[mfascuba]

Originally Posted by waterman46

Safer under power lines? Sounds questionable.

If a lightning strike popped one of those wires off its insulator, I would not want to be there!

If you look at power transmission lines, there is a single conductor over each line (or group of lines) that is not on the long insulators - that's the static ground. It is grounded at each pole, to draw lightning to it and direct the energy to ground as opposed to having a hit on a current carrying line.

[Q Xopa]

Originally Posted by swordds

Thank you for trying to inform this group of something someone might find interesting. Wrong group for that though. These folks are only interested in hearing their own opinions and ridiculing someone else’s.

Yes, much more fun to be resigned to our fate and just wait to get vaporized by a nature sent bolt.

So far I have seen many good suggestions and some very entertaining ones.

Im no expert, but its easy enough to find out what the industry leaders say on this stuff.

It is not a question of avoiding Lightening bolts. More dealing with encouraging any mischievous lightening bolts to take the easy path away from harms way.

Im not sure how any high rise office or apartment building, TV or Cell tower gets by these days, or aeroplane flying through the ITCZ storms gets by without every TV, radio or whatever being toast everytime.

Motorolla have the industry leading Standards paper on this.

Ok a number of years ago before it occured to people to do things like, give a lightening bolt the easist way out and around harms way, as much as possible.

Before this become normal procedure typically every hit resulted in total loss of all the electronic equipment. Now days it is rare anything is fried. But for those fatalists please feel free to keep praying.

Its not too complicated but especially in the last 10-15 years the communication towers, Ham operators etc have worked out things like-
Having a low resistance path leading outside the main electronics cabin to 'Ground'.

Keeping the path to ground outside of the inside of the boat to ground plates in the water.

So guys that are onto this concept bond/ connect the mast to stays, stanchions, handrails, chainplates, using nice thick cables or copper bonding strips, using gentle bends so the big current flow doesnt try to leak out around corners, to the mast in one 'cone of protection' faraday cage setup. Basically leading any large current strike from the mast, to the stays, stanchion, chainplates outside the hull to the grounding plates in the water.

The basic jist is not magic but giving current the easiest path around the sensitive stuff, like radios, humans etc.

Ie keeping it on the outside the boat as much as possible.

High surface area plates, ie machined grooves etc on outside of the hull, not going inside the boat through thr hull to outside. These are best long plates going mast midships to the rear where the propshaft metal is.

Ok nothing is perfect, but this has improved over the bad old days of wishing for divine salvation.

Proof, hmmm, sorry got nothing. Just like I suspect you, or no one else has. However, I know which way I rather place my efforts and chances.

Your call compleþely if you choose to do differently.

Or not, you can simply do nothing resigned to our inevitable fate.

Im sure the insurance and electronics supplier companies dont mind.

[lituya1617]

Call me superstitious, but I drag over side a short piece (10 feet of old welding lead) of copper cable grounded to both sides of my chain plates when lightening is around. The cables make no obstruction and do not have much water drag so I have left them over the side for an entire trip to South America from Miami. I reason that lightening will hit the mast and the majority of the power will go down the stays into the sea. Of course, the mast is keel-stepped and bonded as usual but it makes me nervous to consider 100 million volts trying to find a way out of the inside of the hull, bonding wires not withstanding. High voltages like to find a path on the outside of things because electrons repel each other. Although I have not been hit by lightening, I just feel better giving the electricity a path it usually prefers to ground. Also, even if a bolt of lightening fails to put a hole in the hull, all the sensitive transistor electronics is going to be fried by the magnetic pulse that accompanies the traveling electric field. It's good to have a sextant then because the radio, radar, autopilot, GPS, chart plotter, computers, and everything digital is going to be junk. You will appreciate paper charts and a Coast Pilot at that point. A sounding lead will appear golden.

[captndale]

I think the best precaution is to offer a small sacrifice to Zeus, Poseidon and Aeolus at the beginning of each season or major cruise. Perhaps a bear, glass of wine or shot of rum each would be appropriate. Not too much, you don't want to get too chummy. Just let them know that you respect them.

[Q Xopa]

Originally Posted by captndale

I think the best precaution is to offer a small sacrifice to Zeus, Poseidon and Aeolus at the beginning of each season or major cruise. Perhaps a bear, glass of wine or shot of rum each would be appropriate. Not too much, you don't want to get too chummy. Just let them know that you respect them.

I like it, I'll drink to that.

[Talos]

As mentioned above, knowing that there is lightning in the area "Situational Awareness" is the first step for safety. By putting your backup navigation tool (iPad .. others) and your handheld VHF in the microwave or other safe location is a smart move. The Talos Lightning detector will alert you when the storm front/lightning front is up to 25 miles away and alerts you if it is approaching .. or departing the area. Mention the Cruising Forum and receive 10% off. Also great to carry one in the dink .. you are the highest point ... a heads up to get back to the mothership ... www.shopTalos.com

[captndale]

Turn on an AM radio and tune it to a dead spot on the dial. When you hear loud static from the radio there is lightening nearby.