Lightning Strikes

sailingandsuch · Jan 31, 2013

George,

I have been in your shoes and concerned with the lighting and have done some research several times always coming up with different opinions.

I've heard different things like:
Have a chain you can hang from the backstay into the water during a lightning storm
If you have keel bolts you can run a hefty wire from the base of the mast to the bolts
Or
You can do like I think most sailors do and just go.... (this is what I do....) and if a storm does come up just go below and try to stay away from many metal objects, especially ones that are connected to lots of metal on the boat on outside of the boat.

Your the safest in the cabin but unless you are at anchor you likley would be in your cockpit when the storm hits. In that case, just pray.

This is just what I have gathered over time and I bet some people will have much better ideas that mine. I'm interested in following this thread.

capta · Jan 31, 2013

In over 50 years as a professional mariner, I have had trouble w/ lightning twice. Once it hit the boat next to me (a house boat) and came through the shared power pole and trashed all 115 v a/c systems that were not operating. Another, in the SoPac, north of NZ we had a strike on our wooden mast, but no damage resulted.
In June of 2011, sailing south of Long Island NY, I was hit by a very strong front, which some of you may remember; it was a memorable blow. Winds around 40 knots and lightning the likes of which I had never seen before. Hundreds of strikes per hour and many strikes within the visible horizon. With a 73' spar and nothing taller within 3 miles for sure, why we didn't get hit I have no idea. Many summers in Fla thunderstorms and again. nothing. Many different kinds of boats and materials, so it's not just the luck of one boat.
Being caught in a thunderstorm is indeed intimidating, but it's not near the inevitability that it would seem (being struck) even if you are alone and far from taller objects.
I worry much more about that guy headed toward me with the intention of anchoring right on top of me even though we are the only two boats in a bay the size of Rhode Island!

Rick I · Jan 31, 2013

After being hit by lightning while sailing I read everything I could on the subject. I've concluded that prayer is as good as anything. You can buy those fuzzy bottle washers and put them on the top of your mast or hang jumper cables over the side. It might make you feel better but it won't prevent a strike.

Ken13559 · Jan 31, 2013

I have had electronics damaged by induced lightning surge. Now I fit a 24V zener across all electronics supply inlet, hopefully any transient voltage will get snub out by the zener. Nothing you can do if Thor leaves a calling card.

TLW · Jan 31, 2013

lots of conflicting information on this subject. Google "cone of protection from lightning"

As a sailboat dealer, I had two customers' boats hit by lightning - one of them was hit twice - Hmmmm. So much for that old saying. Both boats had pin holes blown thru the hull causing slow leaks. Boats had to be pulled. The boat hit twice was a San Juan 28. The other was a Hunter 28 that had a factory installed bonding system.

Chris Patterson · Jan 31, 2013

This is one of those subjects that I've spent WAY more time studying than I should have. And still know very little about it, which is about in line with the experts and scientists as well. While I kind of like the idea of the chain overboard attached to a stay, I think it basically just makes me feel like I'm doing something proactive.

A while back, lightning dodged every tall rig in the marina, to hit a small flat jon boat down on the end. Wow.

And some years ago at a home I owned, in the middle of the night, lightning hit, and dodged one of those HUGE aluminum C-band satellite discs on top of a 15 foot pole, a thousand feet of 5 foot chain-link fence, to strike a NAIL I had holding some landscaping timbers together. And by the way, ran through a vent hole in the foundation to the electrics and destroyed every electric thing in the house. Light bulbs, tv's, hair dryers, (I used to have hair then), EVERYTHING. It cost thousands to restore it. A nail, go figure.

And that's just it, go figure. Nobody knows. It's all conjecture and speculation still.

While Forespar makes the "dissipator" look good in their ads, further research blows that theory out of the water. Literally. If it makes you feel better, by all means put one up there. But the bottom line is, it's still very, very misunderstood. And strangely, I think I like that. Some things should be.

So, I too stay low and pray. And also hope that it's not just the last refuge of the scoundrel..

kenn · Jan 31, 2013

From my bookmarks, here's the grandaddy of lightning link pages.

We've been caught out once in a canoe when a storm overtook us, with lightning all around (possibly my most religious experience), and once on an overnight anchored with 11 identical boats, when a thunderstorm system gave us light shows for most of the night. We're all still here...

Here's my conclusions so far:

- (this is a fact) people in a sailboat are much more likely to survive a lightning strike than people in a mastless boat
- the mast apparently isn't as great a lightning attractor as you'd think
- we're gaining understanding of the dynamics of a lightning strike and why it takes the paths it does, but it's far from certainty still. The keel could be grounded, but often there's still some holes punched at the waterline. And so on.
- the wire brushes on the mast are mostly voodoo. More important is to provide an electrical path from the mast to the water that minimizes the risk to people in the cabin.

ken13559 said:
I have had electronics damaged by induced lightning surge.

I haven't lost any electronics yet but I have lost some home-built-LED navigation lights. LEDs can be very susceptible to relatively low levels of reverse voltage, even that from static. I rebuilt them all last year with small capacitors across them, and reverse-biased diodes, and they've survived one season... I'll know better in the spring.

The only absolute for protecting electronics that I've heard of is to completely disconnect them and chuck them in the oven if you have one. It acts as a Faraday cage, protecting the electronics from high-voltage fields.

finding41 · Feb 1, 2013

Next time a storm rolls through check the local lightning strikes on a weather site. You may note here that most of the lighting hits.... land. I don't know why it does. It just seems to. That said. I'm not trying to encourage anyone to go and chase lighting in there sail boat or any other boat.
I just think if you are an inland sailor or close to the coast the chances are better that it will be hitting stuff on land.
Here is a link for Canada. http://www.weatheroffice.gc.ca/lightning/index_e.html
Here is one for the USA. http://www.intellicast.com/Storm/Severe/Lightning.aspx
I think it comes down to this while at anchor. If it hits your boat in the middle of the night you will either be woken up or never wake up.

Bill Roosa · Feb 1, 2013

Lightning protection is not hard. We do it all the time in buildings and it works 99.44% of the time.
Basics to understand:
clouds have electrical charge in them during a thunderstorm
that charge induces an opposite charge in the water SURFACE under the cloud
The electrons don't want to stay separated from their partners on the other side. (other side because it could be a positive cloud or a negative one, up stroke or down stroke)
The lowest resistance path between the two charge "clouds" WILL be used.
masts make good conductors
people make good conductors too but try to avoid using people as part of the circuit, ie don't make a circuit through the boat, make it around the outside of the boat.
The keel does not make a great terminal as the electrical charge has to pass through the plane of the water surface (where the charge is induced) then up to the surface. In those cases it will likely 'go sideways' out the side of the boat near the water line probably near some metal object located along the hull and at the water line.
Sooooo
put a lightning rod on the top of the mast (follow the rules on lightning rods for buildings)
connect all the standing rigging at the deck (metal gunnel works great) to equalize the potential around the deck level
provide a path to the water surface on the outside of the boat at as many places as you have standing rigging entering the deck ground ring (fore--stay, side stays and back stay)
do not connect the mast to the keel as that encourages lightning to come into the salon.
I took a set of jumper cables and cut each into two lengths. clamp the "battery" end to the standing rigging for a good electrical connection and put the other end in the water at bow, stern, port and starboard. Cut the cables to length so they still drag in the water with the boat heeled over. Strip the insulation off so there is metal exposed at the water surface (think short on the heeled over to side and long on the heeled over from side) so there is always bare metal exposed to the SURFACE of the water when heeled.
The lightning will be attracted to the lightning rod and be conducted along the standing rigging to the jumper cable and into the water.
You get the 5:5 guarantee with this system, 5 minutes or 5 feet!!!
Gota be better than running lightning through the cabin though.

Chris Patterson · Feb 1, 2013

Bill, what about out running it? I've got a pretty fast boat.

RichH · Feb 1, 2013

A LOT of changed thinking about boats and lightning has occurred in the past several years. Go to http://www.marinelightning.com to read 'some' of the latest expert opinions. Take a good look at the 'side arc' electrodes to equalize the 'surface' effect.

Ive been 'hit' two times on separate occasions with different boats ... aint 'fun'.