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Thread: Lightning/storms in open water swims - safe distance?.

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    Lightning/storms in open water swims - safe distance?.

    My family has had a vacation/weekend house on a lake for a few years. One of my daughters has made our LSC's open water zones team. That meet is this weekend in Chattanooga. Weather is a threat - first race is late Friday, others are Saturday and Sunday mornings.

    So my question is how you determine when to get out of the water or call off an event? In a pool, generally, if you hear thunder, you get out (and having had a tree in my yard get hit 10 minutes before the rain fell, I get why). However, on large bodies of water, the sound can carry so far, I'm wondering how you determine when you get out? During one weekend last Summer, we got out at the lakehouse when we heard thunder, but our neighbors just ignored it and kept on swimming. I'm guessing we were over cautious, and while I don't want to take chances, during this time of year, we can go on for hours upon hours hearing thunder, and never get hit. So I hate to waste any of the few days we get. Obviously, I'm also wondering what to expect for this weekend, primarily the Friday night race.

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    Moderator Rob Copeland's Avatar
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    Re: Lightning/storms in open water swims - safe distance?.

    So my question is how you determine when to get out of the water or call off an event?
    Since every event has its own unique characteristics, I suggest you directly contact the event director and event referee to find out what they plan on doing at Southern Zones.
    The opinions expressed in the above post are mine and not those of U.S. Masters Swimming.

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    Re: Lightning/storms in open water swims - safe distance?.

    Quote Originally Posted by Rob Copeland View Post
    Since every event has its own unique characteristics, I suggest you directly contact the event director and event referee to find out what they plan on doing at Southern Zones.
    I appreciate that, and could certainly do that, but I'm honestly thinking more in generalities. LIke I'd mentioned, we have a lakehouse. I hosted the local kids on the Zones team for a workout (run by our coach). We may host some more this Summer. Just honestly have no idea how to make the call if it is mine to make. Should I go with a quantifiable (e.g. 20 miles away on radar), or something else?

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    Re: Lightning/storms in open water swims - safe distance?.

    Since you are hosting a USA Swimming workout I suggest you or the club invest in a Portable Lightning Detector. Itís also a good investment if you plan a lot of water activities at the lake house. Now, if it was just you swimming alone Iíd suggest checking a weather app and follow the same basic rules as most pools; if you hear thunder or see lightning, get out.

    There are a lot of Portable Lightning Detectors on the market. Strike Alert, SkyScan, and AcuRite are the industry leader. Weather Geeks has a good review of models from these three at https://weathergeeks.org/lightning-detector-reviews/
    The opinions expressed in the above post are mine and not those of U.S. Masters Swimming.

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    Re: Lightning/storms in open water swims - safe distance?.

    Quote Originally Posted by 67King View Post
    ...That meet is this weekend in Chattanooga. Weather is a threat - first race is late Friday, others are Saturday and Sunday mornings...
    Weather forecasts looks bad fro Friday. But if they do get the swim in it will be fast. The outflow at the Chickamauga dam is predicted at 82,000+ cubic feet per minute. https://www.tva.com/Environment/Lake-Levels/Chickamauga
    The opinions expressed in the above post are mine and not those of U.S. Masters Swimming.

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    Very Active Member Kurt Dickson's Avatar
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    Re: Lightning/storms in open water swims - safe distance?.

    If you ever find the answer to your question, I'd love to hear it. I did a literature search one time and could find no deaths of lightning in water (some cases around water). I would think if you had a near miss, the lightning would go right through you as you are not grounded. It seems you would find more dead fish or sea animals in a lake after lightning. I guess nobody wants to mess with it, but I wonder if you are safer in water (I know, dumb).

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    Re: Lightning/storms in open water swims - safe distance?.

    Quote Originally Posted by Kurt Dickson View Post
    If you ever find the answer to your question, I'd love to hear it. I did a literature search one time and could find no deaths of lightning in water (some cases around water). I would think if you had a near miss, the lightning would go right through you as you are not grounded. It seems you would find more dead fish or sea animals in a lake after lightning. I guess nobody wants to mess with it, but I wonder if you are safer in water (I know, dumb).
    Everything I have found is about pools, not lakes. And yes, the answers are confusing. There are all kinds of speculations about only running on the surface to running through you to ground if you are standing on the bottom. But dissipation is also a thing. An open body of water has so much volume that the lightning would be able to dissipate much more easily than a pool. Conversely, some things talk about how much more conducting wet skin is than dry skin, leading me to believe that the fear is that someone may be more likley to be struck actually out of the pool, but not dried off.

    And like I said earlier, you can hear thunder from such a long way away that the rule of thumb about hearing it and getting out is worthless. Even if I did have a lightning detector, I wouldn't have any idea what would be a safe and reasonable distance. That's kind of what I was hoping to find here, but I'm guessing no one really knows.

    Funny thing about the race this weekend. They moved it. The river is now a flood zone, so presumably the current is too strong. It will now be in an open body of water notably upstream of the city, on the other side of the dam. And they canceled tonight's event, and moved the others. There was to be a masters race, don't know about it.

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    Moderator Rob Copeland's Avatar
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    Re: Lightning/storms in open water swims - safe distance?.

    According to the CDC there on average 33 lightning related deaths in the USA each year. Around 8% of these are water related (boating, swimming, beach Ö); of these most are boating related. So in any given year there are typically 0 to 1 swimming lightning fatalities in the USA.

    Some research indicates that lightning dissipates within 20-60 feet of a water surface strike and in most lakes it doesnít dissipate down more than a few feet. Also water acts somewhat like a Faraday cage dissipating around rather than through objects in it. Some research also indicated that many lightning fish kills may be attributed to the sonic blast and not electrocution. And the sound waves travel much further underwater, so swimming underwater to avoid the surface dissipation is not always a good idea.

    So based on current data the ďsafe distanceĒ is 0 miles. However, if Iím running a race or a USA Swimming practice Iím going to use 6 to 12 miles as my safety perimeter and evacuate the water if lightning is detected in this circle. If itís just me and a small group on training swim, we generally keep going through thunder or cloud-to-cloud lightning or cloud-to-ground lightning more than 2 miles away.
    The opinions expressed in the above post are mine and not those of U.S. Masters Swimming.

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    Re: Lightning/storms in open water swims - safe distance?.

    Quote Originally Posted by Rob Copeland View Post
    According to the CDC there on average 33 lightning related deaths in the USA each year. Around 8% of these are water related (boating, swimming, beach Ö); of these most are boating related. So in any given year there are typically 0 to 1 swimming lightning fatalities in the USA.

    Some research indicates that lightning dissipates within 20-60 feet of a water surface strike and in most lakes it doesnít dissipate down more than a few feet. Also water acts somewhat like a Faraday cage dissipating around rather than through objects in it. Some research also indicated that many lightning fish kills may be attributed to the sonic blast and not electrocution. And the sound waves travel much further underwater, so swimming underwater to avoid the surface dissipation is not always a good idea.

    So based on current data the ďsafe distanceĒ is 0 miles. However, if Iím running a race or a USA Swimming practice Iím going to use 6 to 12 miles as my safety perimeter and evacuate the water if lightning is detected in this circle. If itís just me and a small group on training swim, we generally keep going through thunder or cloud-to-cloud lightning or cloud-to-ground lightning more than 2 miles away.
    Thank you! That's the kind of info for which I'm looking. Read about the Faraday cage thing, too (hence the "wet swimmer out of the water" thought). And I had come to conclude that with my menial understanding of electricity (I'm a Materials and Mechanical guy), that indeed, there shouldn't really be a problem. But anecdotes and "common knowledge" dictate otherwise, and neither mine nor my kids' lives are worth it.

    Were you planning on doing the Rat Race?

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    Re: Lightning/storms in open water swims - safe distance?.

    Quote Originally Posted by 67King View Post
    Were you planning on doing the Rat Race?
    Not this year. Stan and his crew always put on a great event, but I fortuitously didn't get entered on time this year.
    The opinions expressed in the above post are mine and not those of U.S. Masters Swimming.

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