Lightning and sailboats

[Cpt. Jon]

Hello,

I know this is very long, but I wanted to share the experience that leads to the questions at the bottom. With another infant on the way and a ‘new to us’ boat again, this memory has come back and years later I still don’t know the answer to the questions below about lightning. I am hoping that some of you will have some knowledge and/or experience(s) to share with the community. Thanks, and I hope you enjoy the long read!

My wife, 6 month old daughter (at the time), and I set out on our maiden voyage in our sailboat a few years ago. The weather was beautiful and it was mid-afternoon very early summer. Enough time for us to sail leisurely and motor-sail if needed to get the boat home from the yard with plenty of time to spare. We didn’t check an updated forecast or radar which turned out to be one of the biggest learning mistakes we’ve ever made.

We got clobbered by 3 severe thunderstorms for 3 hours, with winds topping 50+mph and over 1000+ lightning strikes in our area in those 3 hours. By the time the storms were closing in on us, we were at the mouth of the York River heading into the Chesapeake; I had to go with my instinct which was to find a sheltered place to ride it out, we couldn’t make it back to the marina in time. I tried to get into a channel that I normally can get into at anything but low tide, and started to rub the bottom, I decided that I didn’t want to be aground with high winds and this storm and made a quick turn back out deep enough be clear and we were sheltered enough there that big waves off the Chesapeake and York shouldn’t effect us too much. I dropped anchor and set it well and we sheltered below.

For the next three hours of phone calls, and coast guard chatter about capsized boats on the bay by this sudden storm on the radio, I kept wondering if we were doing the right thing. I didn’t want to be on deck in the event of a lightning strike, but I REALLY didn’t know if it was safer below. The mast is deck stepped and I figured the whole hull may basically become charged in the event of a lightning strike, and a keel stepped mast would have been safer.

As the boat wandered back and forth on the anchor line in the gusts and at times heeled so much that it seemed we may get knocked down, my daughter slept peacefully through the WHOLE ordeal, I had fear of a lightning strike or something else and was prepared to have to call the coast guard and ‘abandon ship’ if the time came. My wife was calm and seemed to have more faith in the boat and my decisions… I grew up on the water, have lived on the water most of my life, but rarely have I been in a situation like this (a few experiences in Iraq being an exception), motor boats can outrun storms, but you can’t outrun much at 5 knots (lesson learned).

Eventually, the storm started to clear, visibility got better, and the lightning subsided. I pulled anchor, and we made a B-line back for the marina, which was closed at this time. The sun was out that evening and it was once again peaceful. Some friends met us at the marina with some towels, food, and dry clothes (sailors as well and the friends that we bought the boat from). They worried the whole time we were out there and we’ve talked about it numerous times. In the end, just about everybody I’ve talked to said that I made the right decision to ride it out as we did, and I almost always go with my instincts. I installed a radar application on my cell phone the next day and we’ve never been on the water in a storm since, but it’s a matter of time, not every cruise can be as lucky as we have been the last couple of years.

My questions are: What about lightning? With all that lightning around, I can’t believe we didn’t get struck, to be honest. I am glad that we were fairly close to shore because the trees were more likely to get struck, I guess. What happens when a sailboat gets struck? What is the safe course of action in a situation like we were in? Where should you be in the boat in a lightning storm? I assume away from metal and the bulkhead under the mast, we were near the companionway and my daughter was sleeping on the bed made from the settee table and benches.


Thanks for the input,

Jon

 

[kloudie1]

Interesting. My boat was struck while in the slip. I was not aboard. You can see my slip on Google Earth at 30º21’ 04.96 N and 90º03’13.42W. There are trees close by (within 55 feet) that are higher than my mast which is 53 feet to the top of the VHF. The VHF aerial and the radio itself were smoked. The light bulb in the AC panel for the reverse polarity indicator was blown across the cabin and was on the table. The light bulb in the stern navigation light was exploded. The steaming light and mast-top anchor light were fine. The nav light breaker on the electrical panel had the aft end of its case blown off but it still functioned. The power fuse in my old LORAN was blown out but it works fine after the fuse was replaced. The aerial is on the stern rail, close to the stern light. The antenna coupler in the base of the aerial was not damaged. There are interesting oxidation trails in the black paint on the back side of the electric panel, travelling from the blown nav light breaker case to the green ground buss of the AC panel. I had replaced all of the indicator lights of the DC panel with LED’s and all are still functional. Sorry about the blurry pictures. Some of the Interlux 2000 barrier coat on the iron keel was blistered when I pulled the boat three years later, but I don’t know if that was caused by the lightning leaving the keel or was (more likely) due to the crappy yard work. While anchoring during a storm off Horn Island, Mississippi, a few years back, lightning hit the water about 300 yards away.. Nothing taller than my mast for a few miles..
Leaving Gulfport, still in the channel, for the start of the Gulfport To Pensacola Race, a J-30 about 100 yards in front of us was hit on the mast top. We saw the VHF aerial blow up, lots of fire up there for a second. There were 5 people in the cockpit.. We could see that they were very excited for a few seconds but everyone was fine and they finished the race.. They lost their wind instruments in addition to the VHF.
No one can predict..

 

[sailingdog]

Dropping anchor is a good storm tactic if you have decent ground tackle. If you have an all chain rode, that might increase your chances of getting hit. Thre are basically two schools of thought on lightning and boats.

The first is that you should ground the mast and have heavy bonding between the stanchions, chainplates, pulpit and such to the mast. This should give you more protection in the case of a lightning strike by forming a "Faraday Cage" to protect the occupants of the boat. However, statistically, boats that are well grounded tend to get hit a bit more often.

The second school of thought is that you shouldn't ground your boat. The idea being that you're less likely to get hit. However, if you do get hit, the damage tends to be much greater.

If you have a keel-stepped aluminum mast, creating a lightning ground path is relatively easy. For boats with deck-stepped or non-aluminum masts, it is a bit more difficult.

 

[Mike B]

Sounds like you did all the right things. Lightning is an interesting phenomenon. It's unpredictable and random in the way it impacts what it hits. We had a near miss a few years ago. While trying to avoid one set of cells we encountered another. Knowing we couldn't dodge it we motored on. I watched my wind display go blank and moments later a bolt struck about 100 yards out. Nothing else around but us. No damage to the boat. I also know of two others that have been hit, both while tied to a slip. One was a power boat, the other a sail. Both sustained losses to their electronics. I've also heard in rare cases of thru hulls being melted. As for your hull becoming "live" that wont happen as it's fiberglass and wont conduct electricity. The mast and shrouds should shunt it safely away from you. Actually the cockpit is a safe zone in that all the metal surrounding it forms a cage. The metal in the cage conducts the charge thereby keeping you safe. That said I'll add that it's wise not to hang onto or lean against anything metal during a storm as the voltages lightning produces are quite large and can potentially harm you if you're touching metal during a strike. Some times it's just a matter of hanging on for good luck.
Mike

 

[Ross]

Lightning is so unpredictable that you can do everything known to the mind of man and you neighbor can do nothing and for the next fifty years neither of you will get hit. In a marina with a thousand boats one may get hit and it may not be the tallest, it may be in the middle of the fleet or it may be out at the edge. It may or may not have any provisions for lightning abatment.

 

[Cpt. Jon]

I guess I have seen the "cage" that is created by the stays etc on that boat when looking this up a few times, I think that since it was tiller steered, holding onto the tiller bothered me. Good point about the hull being fiberglass.

I wonder if the boats in the slips get it worse because the lightning finds the path through the pilings the easiest and jumps and travels through the electrical system to get there easier. boats at anchor may provide an cleaner path to travel. And boats not at anchor or in a sliip it might just come down the mast and seeks it's way to the keel and out the fastest. Scary stuff to me though.

 

[Mike B]

Capt Jon, it's a good time to convert that tiller to a nice wood one

 

[Bob Poff]

Talked to a guy at the marina one day. He told me this story:

He and his wife got caught in a thunderstorm. They were anchored fairly in the open near Turkey Point on the Chesapeake. Took shelter below. During the storm they heard a loud BOOM. (I forget if they saw a flash or not.)

After the storm passed he hopped over the side (Mac 26 wth the keel swung up in shallow water) to inspect the boat. He found what at first he thought was some "fly crap" just above the water line. Then he noticed that the specks formed a line.

Some time later in the the they both began to feel ill. Nausea and trouble thinking.

They went to the Doc. He said "You've been hit by lightning".

The specks of flly doo..... pinholes in the hull.

 

[Cpt. Jon]

Capt Jon, it's a good time to convert that tiller to a nice wood one

Oh, it's wood but connected to metal and it does go through what I would imagine to be that electrical "cage".... I guess wood isn't a good conductor, but still..... anyway I have recently upgraded to a new boat that has a wheel though.

Ross: I know you are right, and I really am really glad to hear these experiences people are sharing and especially measures people take in a storm and what happens. As you know, the everday forcast in summer on the Chesapeake seems to be "Chance of Isolated Thunderstorms". I know some people have rules of getting to destinations early so they are their their before most afternoon storms are setup.

 

[Ross]

We had an old dead snag in the back yard year ago. It was about 75 yards from the house. One night we had a storm and lightning hit that tree with a boom like a couple of sticks of dynamite. The next morning I found chunks of bark within thirty feet of the house. I hate to think what a strike of the force could do to a house or a boat.

 

[Chris Burti]

I can relate my experience for whatever that may be worth. We sail in an area prone to frequent and sudden summer squalls that are often accompanied by high winds, driving rain, hail and lightning. If you are going to sail in the summer around here, you are going to have to risk it some. That is not to say that I would voluntarily be out in a bad forecast. Enough experience with these squalls makes you just comfortable enough to forgo putting on a pair of Depends with your foul weather gear yet leaves you as nervous as fox in a pack of hounds.

When I see a squall line approaching, I immediately drop and secure all sails and lines. I rarely anchor because I don't trust a hastily set anchor in those conditions, though many do. Assuming that the squall will miss you is a sure invitation to disaster. However. they usually pass quickly, but you should expect the wind direction to reverse itself and end up with a significant shift.

You should expect gusts up to 40 knots which can lay you over to 30 degrees under bare poles and will knock you flat if any sails are up or break free. Hail can be painful and horizontal driving rain will make it difficult to see. Visibility will drop to less than a boat length. I've seen lightning hit the water less than a boat length away on several occasions.

I've been hit by lightning just once while aboard in over forty years of sailing. Wouldn't care to repeat the experience. I was at the wheel of a friend's Pearson and the rest of the crew was down below with instructions to stay as clear as possible of chainplates, mast and electrical panel.

When the lightning hit, I saw a blinding flash, but didn't notice much sound. The crew later reported hearing a huge boom and feeling tingly, but didn't notice any flash...go figure. Immediately after the flash, I saw molten metal hitting the foredeck. I reflexively jerked my hands off the stainless steel wheel. My first conscious thought to myself was "Well Cap'n Stupid...that's a pretty dumb move...too late now to zap you!"

Insurance (less the deductible) took care of the VHF whip, Wind sensor and Windex, all of which were vaporised, the damage survey, haul-out, and the replacement instruments. The only real damage to the instruments was that the SeaTalk capability was fried and the hull survey came out clean.

You kept your head, made difficult decisions and kept your vessel and crew safe in trying conditions and did not add to the risks. My experience leads me to offer no criticism whatsoever to your handling of your situation. I have seen no substantiated, quantitative scientific evidence that any particular anti-lightning trick or device is materially any better than any other or even better than snake oil. In this context, 'random' is more than a mere buzz word, pardon the puns.

I would suggest that while second guessing in a storm is normal, changing one's mind in the middle of a crisis when circumstances haven't leads to poor decision making.

 

[txjim]

There are trees close by (within 55 feet) that are higher than my mast which is 53 feet to the top of the VHF. The VHF aerial and the radio itself were smoked. No one can predict..

When we run lightning protection analysis on multiple antenna fields, a 45 degree cone of protection is modeled. If you are right next to a taller structure, you may have protection but this depends on conductivity as well. Best bet for protection is next to a taller mast or other large structure.

Regarding using anchor+chain for grounding: Don't remember the factors for water to metal conduction. For proper grounding on earth, a minimum of an 8 foot rod is required under normal circumstances. There was a recent post talking about a jumper cable dangling in the water as a ground point. This is guaranteed not to work.

 

[Mike B]

Capt Jon, not that it's an issue now that you have a wheel but wood is an excellent insulater. Much better to have your hand on that in a storm than on a wheel. That's when it's time to use the autopilot or lock the wheel down so it steers without touching it
Mike

 

[kloudie1]

Remember that the wheel (ok, most wheels) is connected directly to the metal skeleton (ground) of the rudder through cables and chains..
More stuff .. The mast on the Hunter 34 is deck stepped but it does have a heavy wire, 8 ga, straight through the compression post to the keel. The wire was closely inspected after the hit and no problem was found. The chainplates are grounded that way as well.
Another hit story.. The guy I sold my Spirit 23 trailer-sailor to a few years back was hit. He was in the cockpit and his wife was inside the cabin. He was hanging onto the wood tiller and reported a flash and a lot of bang, but was fine, other than commenting that his laundry folks would know how scared he was. There was no mast ground. Wife in the cabin reported a flash inside along with a pop. The cabin overhead lights (3) all blew up, spreading glass all over. The lightning went through the hull on its way out . The hull had two spots about 1 foot square on each side of the keel where the resin had been pretty much melted through leaving those spots oozing seawater through the glass mat into the boat. They were able to get to the yard using a manual pump every 10 minutes or so for the three hours it took to get to the yard and put her into the slings of the Travelift®. The keel on that boat is a fiberglass shell molded into the hull into which a bunch of lead shot is poured and sealed with epoxy (no ground available). The swing keel has no metal in it, other than the lift bail and pennant.
You are right, Jim.. I’ve done the same for tall pressure vessels in petrochem plants but what strikes ya (small pun there) is how small the cone actually is, which leads to the strange patterns of strikes amongst a forest of tall things. My neighbor’s mast top vhf antenna is outside of my cone but he had no damage from “feeders” at all.

 

[Pops]

Lightning is crazy stuff. I've never been hit while on the boat, but I get real nervous in thunderstorms. Several years ago I was enjoying a cold beverage under my house (my house is on 8ft pilings) with my next door neighbor when the house across the street was hit by lightning. A side flash traveled 100ft to where we were standing. My next door neighbor was knocked to the ground and I had lightning flash into the palm of my hand from the metal door that I was standing near. He was unhurt, but it took me a couple of years to recover from the nerve damage to my right arm. The house across the street lost almost every electrical item. I hate lightning.:cussing:

 

[CalebD]

Here is a link dedicated to research on lightning by the U. of Florida (lightning capital of the US): http://www.lightning.ece.ufl.edu/

and more specifically related to lightning and boating: http://www.cdc.gov/NASD/docs/d000001-d000100/d000007/d000007.html

 

[higgs]

The Faraday concept is demonstrated in this video of a high tension line worker. interesting video
http://www.youtube.com/watch?v=EQYDToVK6Z0

My boat got hit in its slip and cost the insurance company over 4k. This is what it did to my battery charger located in the engine compartment of my old Irwin. All ohter electronics were toast and allthrough hulls had to be replaced.

 

[Mike B]

I don't know how much the man in that video makes but it's not nearly enough. Better him than me up there.

 

[sailingdog]

Seen that video before... They don't pay that guy enough IMHO. That suit, being Nomex and Stainless Steel, must heat up on a hot summer day like nothing else...

 

[Don12364]

Insulators - No such thing in a thunderstorm

When it comes to lightning there is no such thing as an insulator. A 'spark' which can travel thousands of feet in air will have no trouble in passing through fibreglass or wood - either through the laminate or along it. Indeed it can easily carbonise the material in an instant whence it becomes a good conductor.
The Faraday cage theory is the best idea yet (I once did physics experiments in the lab where Faraday worked). The 'cage' is theoretically a cone 45° cone from the masthead - but my boat has no backstay!

Lightning storms are often quite localised and on two occasions I have monitored the track and then sailed right round the storm noting the extraordinary wind changes as we went - the wind blows towards the center so we sailed a course round half a circle whilst close hauled all the time. Once we weighed anchor and left the cove we were in because we were directly in its path. As a result we saw nothing of the big winds in the centre. Fortunately we found searoom for this but it only required a couple of miles deviation.

As Ross says lightning is so very unpredictable as to where it will strike.
I also subscribe to the concept that it could be best to be near to something tall and conductive like another taller boat; but so why do they tell you not to stand under a tree? Many golfers die this way.