Lightning Strike on a 34' Searay

JByers

JByers

New Member
Oct 14, 2008
29
Woodstock, Ontario, Canada
Boat Info
340 Sundancer 2001
Engines
6.2s 320hp
I got caught in an extreme storm last week, lightning all around hitting the water. What happens if it hits the boat? I have a 34' 2001 Sundancer. Thanks John
 
What happens when it hits the boat will vary widely depending on whether the boat is equipped with a lightning protection system, or not...

If not (and most cruising boats aren't) the lightning is going to seek a path to ground and there's no way to know where the electrical charge is going to flash while seeking a path to ground and what's going to happen at that point. Best bet is to anchor up and go below to wait it out. I've got outriggers which are a huge lightning rod, so I drop them when lightning threatens. An alternative would be to ground them by clipping a heavy gauge wire to them and trailing it in the water; but there's the paradox. Installing a lightning protection system actually invites lightning aboard the boat since you're creating a direct path to ground- which is exactly what lightning is looking for.
But, boats with an LPS will withstand a strike better than one without.
 
A boater was killed at my boat club at ramp many years ago when his boat was struck by lightning waiting to trailer it during a storm. Cardiac arrest and hundreds of holes in the hull!
 
That article confuses cages and cones. The Faraday cage only tangentially pertains to lightning. Its purpose isn't lightning protection. There must be a better reference available that that.
 
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At least if you are in the slip there are sailboats around and they are more likely to get hit than you!
 
When I stuck the big antenna mast on my hardtop, I looked into the lightening protection aspect as I now have about 30 pounds of ungrounded aluminum over my head. On top of that, I have a big grounding plate for a SSB radio that is a perfect RF ground and lightning loves that...

I've read several stories about lightning hitting boats (sailboats) and killing people. There are feeder bands that come off a lightning strike so it's not a clean "point A to point B" thing... it engulfs the whole boat... grounded or not... It's like trying to predict weather or a woman's mood.... forget it.

Unless you have an all metal/steel boat you are sitting in (like a car), I basically think you are screwed...
 
If you're number's up, it's up.

There was an article in the paper when I lived in Florida ('79 or '80). Three men on a golf course, running to get inside during a thunderstorm. The man in the middle was struck and killed. The two on either side were unharmed.

Go figure.
 
AndersonAcres said:
If you're number's up, it's up.

There was an article in the paper when I lived in Florida ('79 or '80). Three men on a golf course, running to get inside during a thunderstorm. The man in the middle was struck and killed. The two on either side were unharmed.

Go figure.
Click to expand...


--------------------------------------------------------------------------------

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SPORTS ACTIVITIES & LIGHTNING INJURIES
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Lightning is among the most awesome and frightening phenomenon known to man. In the US an average of about 100 people die from lightning strikes each year and about 250 are injured. About 30% of lightning strikes to humans result in death.

The sports activities that are associated with the highest number of lightning injuries and deaths are water sports, golf, camping, hiking, baseball and football. Most fatalities occur in water-related activities such as swimming, fishing, and boating. The risk exists not only in water, but also next to lakes, rivers and on beaches.

LIGHTNING FACTOIDS

° A lightning stroke discharges about a 100 million volts of electricity and travels at 87,000 MPH.
° The temperature along the lightning path is about 54,000 degrees F (30,000 C), six times hotter than the sun's surface (9,940 degrees F).
° The sudden air expansion creates a shockwave which is heard as thunder.
• The average lightning bolt is about an inch wide and five miles long. The longest lightning bolt ever recorded crossed 118 miles in the Dallas-Ft. Worth area.
• Lightning can strike like a "bolt from the blue: —from a clear sky without threatening clouds. However, the source of lightning is a parent thunderstorm that coulde be 25 miles away from the lightning strike.
° Time in seconds from lightning flash to thunder divided by 5 = Distance in miles from lightning source.



SOURCES
Lightning Injuries: Who Is at Greatest Risk?
Michael Cherington, MD / Physician and Sports Medicine. Vol 18. No 8. Aug 90
The facts behind lightning's flash
By Karl Gelles and Bob Swanson, USA TODAY . 5.21.2008
http://www.usatoday.com/weather/resources/graphics/2008-05-18-lightning-flash-graphic_N.h



Lists & Tables
 
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I thought I read somewhere that if you are in a small boat and can get with in this cone of a sail boat you should if you can't get out of the storm???


LIGHTNING PROTECTION CODE
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The National Fire Protection Association, Lightning Protection Code, suggests a number of ways in which the boater can protect his boat and minimize damage if the boat is struck or is in the vicinity of a lightning strike. These suggestions are summarized below:
  • A lightning protective mast will generally divert a direct lightning strike within a cone-shaped radius two times the height of the mast. Therefore, the mast must be of sufficient height to place all parts of the boat within this cone-shaped zone of protection (see Figure 6).
http://www.nasdonline.org/docs/d000001-d000100/d000007/d000007.html
 
If you live, you call your insurance company to repair or replace your boat.
 
10. MYTH: Go near a tall pointy isolated object when thunderstorms threaten, to be within the 45° “cone of protection”
TRUTH: The “cone of protection” is a myth! While tall pointy isolated objects are statistically more likely to be struck
by lightning, it’s not nearly reliable enough to rely on for safety. Lightning can still strike you near the tall
object. Besides, the lightning electricity will likely spread out along the surface of the ground and can still kill
you over 100 Ft from the “protecting” object. Also, if you are close to or touching the tall object, you can be
electrocuted via side flash or contact voltage.


There is a lot of current research (including people who have been zapped and killed) that point to the whole thought of being in a safe zone of a "cone" as being BS...

http://www.lightningsafety.noaa.gov/pdfs/LightningMyths-1.pdf
 
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Jack F said:
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I thought I read somewhere that if you are in a small boat and can get with in this cone of a sail boat you should if you can't get out of the storm???
Click to expand...


I have a friend with sailboat who we raftup with very often, does this mean that if we're caught in storm while anchored I should tell him to that we need to split until storm passes since his boat is most lightning inviting object near me?
 
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When I have been in raftups, we tend to break up BEFORE the storm because of potential anchor drag issues. (don't want a single anchor holding multiple boats)
 
Last year lightning hit the mast of a sailboat while in a slip in our marina. The end result was almost every boat in a 50-75' from that sailboat suffered severe damage to their electronics. Yes, lightning can be weird.
 
Not boat related, but interesting personal experience...

Last summer while none of us were home, lightning hit near the top of a very tall (~140ft) tulip poplar tree about 15 feet from the corner of our house. This tree is 36" in diameter. About 4 ft. away from this tree and aobut 15' up, the power line and phone line for our house ran by. The lightning blew the bark off the tree in a nice line all the way down the tree until it got to the phone line, 4ft. away. The tree was clean from there down. But the Verizon phone box on the side of the house was blown to bits, along with some of the vinyl siding around it and the ground wire going behind it to the ground.

All of that electricity figured it was easier to make it to the ground via the phone wire and grounding wire, than to finish the job in the 3ft. diameter tree. So even a little grounding wire that is very conductive helps a lot...

Tom

btw, the tree survived...
 
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I really appreciate all the information everyone has shared. I know I'm going to pay a lot more attention to the weather. We where a long ways to shore and a lightning strike could have taken all three of us out. Thanks John
 
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