Swimming With Lightning

[OutlawCaver]

I felt the following was worthy of its own thread:

For a submerged diver or surface swimmer exposed to a divergent electric field like that created by a lightning strike, the following apply:

Sea water: The resistivity of the water is low and conductivity is high as compared to fresh water. Therefore, the worst case scenario is being upright in the water column with hands at your sides facing or your back to, the point where the strike occurs.

Fresh water: The resistivity is high and conductivity is low. Therefore, the worst case scenario is hands outstretched floating or swimming horizontally in the water column with head or feet pointing toward where the strike occurs.

Obviously, you don't have advanced notice as to when or where the strike will take place so you can't orient yourself according. You can however, improve your chances on the surface by swimming horizontally in sea water and swimming vertically in fresh water. If the lightning strikes you or in very close proximity, it will be of little consequence how you orient yourself in the water.


For eggheads like me, I have the electric field gradient and current density equations and graphs to support these recommendations if you are interested.

[Moonfuzzy]

Does that mean cave divers need to start swimming with our head up and fins down for our own safety?

(hee, hee)

[Angie Reim]

Yeah well I'm an egghead too and I don't need to see the graphs to know that it hurts no matter what position you happen to be in at the time.

[JE]

I should have grabbed that eel I saw coming out of the ceiling in Luraville 1 during a storm. Then it could have been called a true electric eel, Huh-. I don't like lightning, at all. My hair really does stand on end from it-!

j. 8)

[sskasser]

Good info Vince, thanks.

Vertical in the caves? I think I'll take the chance with lightning. Somehow, the thought of my old cave instructor happening along in PI while I'm swimming vertical is scarier than a bolt of lightning.

[Guy Bryant]

In 1981 Lee Sams and I were laying line in the downstream section of Thunder Hole. Our total time under water was about 5 hours. While decompressing at our 10 foot stop a bad thunder storm came up and washed a lot of mud into the basin. Our vis went to about 6 inches but you could hear thunder and see the water light up every time lightning cracked over our heads. On top of that when we saw a flash of light our lips would tingle with the electric charge. This concerned me as I was wearing nice lightning attracting metal tanks on my back. I decided to take my tanks and deco bottles off durring the storm to possibly prevent me from being fried if lightning did strike the water. I hoped I would have a better chance without metal on my back.

I consoled myself with the idea that fish were in the basin and thunder storms are quite common durring the summer. I figured if lightning had struck the basin in the past and the fish survived maybe I would too. All kind of ideas run through your head when you feel the tingle of electricity on your lips every time lightning flashes. We had just started our 10 ft deco when this occured so I was hesitant to leave the water, still had 99 minutes to go. Let's see - electricuted by lightning or bent? Lee and I decided to take our chances with the fish. We survived but it was hair raising at the time.

[OFG-1]

Does that mean cave divers need to start swimming with our head up and fins down for our own safety?

(hee, hee)

NO, however all should carry a 8' long copper rod to pound into the earth at our 20' stop, a length of 4/0 electrical cable with a large clip on the end, like the end of a jumper cable, and enough tools to pound in the rod, attach the cable to the rod, attach the clip to the cable, and then be quiet enough to attach the clip to our buddy's manifold.