Lightning question

[H2O Gal]

We just got back from a trip in the Bahamas and while we were there a man who had just arrived was in a lagoon at the Wyndham during a lightning storm and he supposedly got struck while standing in waist deep water. He died and witnesses said he had severe burns on his entire upper body. Although this isn't a scuba incident it got me thinking--what happens if you are on a large metal dive boat several miles offshore and lightning hits the boat? Or hits the boat while you are nearby it in the water? I'd think that salty water is quite conductive...:shocked2:

 

[joystershell]

Check out this story.........

Diver struck by lightning in FL

 

[openmindOW]

what happens if you are on a large metal dive boat several miles offshore and lightning hits the boat? Or hits the boat while you are nearby it in the water?

Excellent questions, H2O Gal. Thank you. I'm not qualified to answer, but I look forward to reading knowledgeable responses.

 

[victor]

Here are my thoughts
If you are inside a metal boat then no issue. The lightening is going to be conducted through the metal boat, not you. This is similar to an experiment where a car was struck by artificially generated lightening, no problems.
If you are in the water and the boat is struck by lightening, also no problems. Lots of electricity in the sea but no reason for it to pass through you.

Now for the very unluck man in Florida. His tank was struck, his surface area is very large, compared to the tank, so the electricity chose that path stopping his heart on route. He must have been increadibly unlucky as the tank can only have been a few inches above the surface wheras the boat would have been a much bigger target.

What to do if you find yourself coming to the surface in a thunderstorm?
That is an interesting question.
Do you stay below the surface until you run out of air?
Do you dump your tank, BC, and regs before attempting to get on to the boat?

Thoughts please

 

[Haiko]

I don't know If just dumping a Tank and BC would protect you from being hit by lightning.
Sometimes cow (no pun intended) are struck when they are just grazing in the fields. And they don't have any metal on them. I'll guess lightning can struck just about anything. Metal or not.

Correct me If I'm wrong.

 

[kaerius]

Lightning tends to strike higher things before lower, though conductivity has a role too.

Basically, if you are swimming out in the open waves you're more likely to be struck(being the highest and most conductive object around) than if you're close to the boat(in which case the boat is more likely to be struck).

Personally I'd go for an underwater swim all the way to the ladder.

Ditching gear while going up isn't going to help at all unless you actually leave it in the water... in which case there may be a minute lessening of risk.

Though note that you may feel some effects of the lightning if it hits the boat and you're next to it in the water...(just like you should never hide under trees in a lightning storm).

 

[Starcruiser]

Excellent question... I've wondered about it myself. Common sense would say to stay out of the water if there's a thunderstorm, but if one pops up while you're out, what do you do? I've always played it safe and if it LOOKS like there are boomers nearby, I opt out of the dive.

 

[bsee65]

The gear ditch could help you get aboard more quickly once you reach the ladder, depending upon the circumstances. Still, that could be an expensive decision to expect someone to make on the very slight chance of suffering a strike. Maybe if you had a net on a line that the gear could be placed in and recovered it would be an easier option to select. Of course, if you're planning for that eventuality, maybe you should have thumbed the trip to begin with.

 

[Garrobo]

Just as an aside to cows being hit now and then, I was reading about animal strikes a few years ago (why, I don't know) and read the fact that lots of complete elephant carcasses have been found in the African bush which had been struck by lightning and killed. No other explanation could be found. So my opinion is that I wouldn't recommend that any elephant go divng off of Deerfield Beach in a thunderstorm. Other than that, when your bell rings......................

 

[Crush]

From my response at http://www.scubaboard.com/forums/basic-scuba-discussions/337783-lightning.html#post5279604

From a perfectly physical perspective, electricity takes the path of least resistance. This is why many people who survive lightning strikes are found naked and burned, but alive - the electricity flowed around their bodies, through wet clothing and along wet (salty) skin, causing the water to boil and their cloths to blow off. Many lightning fatalities are found perfectly clothed - their dry skin and cloths did not conduct, therefore the lightning went through them.

From that perspective, being immersed in a conducting medium - good stuff! Fresh water is good (fresh lake water conducts well - there are many impurities), but salt water is even better.

Later edit: The above situation assumes that you are not wearing any metal. Obviously this is not the case if you are diving. To a crude approximation, our tank will "attract" lightning (by having charge induced in it by the developing lightning discharge), but this charge will be over a factor of 80 times more intense where your tank is exposed to the air as opposed to being immersed in water.

Further reflections: Salts in decaying matter at the bottoms of lakes may make that layer slightly more conductive than the bulk of the water.