Lightning + Mast = ????

RichH · Jul 15, 2012

Ive been hit several times. If the boat is well bonded (all metal objects electrically connected by heavy wiring, etc.) and there is an 'easy' pathway overboard for the lightening strike then there typically wont be much structural damage, other than 'fried' electronics.

There has been a continual 'shift' in the current thinking of how to keep lightening out of the inside of a boat. Here's the probable latest thinking on the subject: http://www.marinelightning.com/
The person who runs this corporate entity was the famous 'lightning guru' at the University of Florida and his recommendations for marine protection then were probably the most sought after in the entire country.
Apparently his thinking has evolved since his retirement to start a commercial marine lightning protection company - multiple 'sideflash' electrodes installed along the boats waterline, etc. etc. to help get the strike 'out' of the boat.

kloudie1 · Jul 15, 2012

not long after I sold my Spirit 23 to a friend, he was hit .. Wife was inside the cabin .. the light bulbs inside and in the navigation lights popped .. She was not hurt.. He was at the tiller and also was not hurt.. The lightning did jump from the chainplates and out the hull.. It vaporized the resin in a couple of spots below the waterline leaving a gauze of fiberglass cloth that wept water .. He was able to manually pump and got the boat back to the boatyard and on the hard so she would not sink. It was repaired and no other problems were noted.. engine had a non-electronic ignition system, and there were no electronics on board when they were struck..

Douglast · Jul 15, 2012

i often think the path the lightening will take is from the mast to the bottom of the mast then bursting sideways through me on the way to the outboard as im on the tiller ..

regardless i am going to connect the mast to my drop keel with #4 wire and my shrouds and forestay with #6 to my keel or a seperate large conductor that i can put in the water.

i am going to try for wiring that can be non permanent but quick to "hook up"

i want to be able to pull the sails,throw anchors,hook up ,lift outboard and get in the cabin...lol..

onecoolair · Jul 15, 2012

Back when we were doing a lot of J-24 racing. Sometimes we would get caught out in some pretty nasty lightening storms. We would connect the spinnaker pole and drop the other end into the water and then hunker down pray and wait it out.

AtlanticAl · Jul 15, 2012

You take some of your mooring chain, wrap it round your mast, drop the other end into the water. Then unhook your VHF, and MF radio if you have one. You stick any electronics such as walkie talkie or epirb, in the oven (which is a faraday cage) Then you hope you dont get hit.

If you have a carbon fiber mast, then good luck, those things explode when hit. I have sailed right through a lightening storm, and not been hit, i think its a tiny chance you ever will be hit. What i thought in the first storm, was my boat is the highest thing around, but if you think of it, if the lightning comes from right above you, then your boats mast is the closest thing to the earth, but unless it right above you, your thirty foot mast is not the closest thing, if its off to your side, lightening takes the shortest path, if its a hundred yards to your side, then the shortest path is still into the sea. To hit your mast, means it has to travel, a longer distance.

kenn · Jul 16, 2012

Protection of Trailer Sailors...

Douglast said:
...I am going to connect the mast to my drop keel with #4 wire and my shrouds and forestay with #6 to my keel or a seperate large conductor that i can put in the water.

Having a similar boat, my feeling is that you should avoid anything that would guide lightning in or through the cabin, and I'd also be concerned that any connection to your drop-keel becomes a potential failure point in case of a strike (pronounced "sinking") . The 'lightning' wiring itself could explode or melt in the cabin... not so nice for anyone inside.

From reviewing this subject and reading most of the experts, my conclusion is closest to Atlantic Al's. I'd use something like jumper cables clipped to the mast base, the other end clipped to a metal bar or chain and overboard. The idea is to route the energy into the water through the heaviest path possible (mast & jumpers) that protects the cabin.

I would not bond the shroud bases; our stays are only 1/8" ss wire and could fail if required to carry heavy current.

And seconding the disconnection of electronics, especially antenna leads, to try to minimize equipment damage.

onecoolair · Jul 16, 2012

Slow Mo^cean said:
I like the jumper cable idea. I think from now on, I'll carry a set or two and connect one to the mast and one to one of the stays.

Best if you can drop one end of jumper cables into water. All those extra amps needs to go somewhere and overboard is best.

KD3PC · Jul 16, 2012

Were I you guys, I would really research the idea of chains and jumper cables....they are way too "iffy" a connection to provide ANY safety..read high resistance path, link gap, connectivity, current capacity of chain link and jumper cables, add wet to the above...etc

else Darwin will have his way....

You can actually make the chances of a hit better, or worse disturb the "natural" shedding provided by the design of the boat...

All that being said, it is your boat and your butt...but don't be surprised if you get a hit and the insurer does not pay....anything....for your efforts.

YMMV

kenn · Jul 16, 2012

KD3PC said:
Were I you guys, I would really research the idea of chains and jumper cables....they are way too "iffy" a connection to provide ANY safety..read high resistance path, link gap, connectivity, current capacity of chain link and jumper cables, add wet to the above...etc

You can actually make the chances of a hit better, or worse disturb the "natural" shedding provided by the design of the boat...

Um, what? Do you speak from experience, or are you thinking out loud, like the rest of us are?

What is this "natural" shedding that is part of the boat design?

I do have an electrical background, and I've tried to stay current with the issue of lightning hitting boats, and the possibilities for protection. The common denominator of most solutions is that you try to offer an easy path from the masthead to the water, that will minimize injury to occupants and damage to the boat.

Referring specifically to our small trailer-sailor, real no-sh1t 100% effective lightning protection is prohibitively expensive and not justifiable. The preferred solution is to not be in the boat during lightning. But IF we are caught out in lightning, all we can do is to make it easier for lightning to get where it wants to go via the outside of the boat, while we remain a bit safer inside the boat.

If the choice is between nothing (which means any lightning hit will have to arc the last few inches to the water, and is therefore unpredictable; could burn someone or hole the hull) , and doing the chain or jumper-cable thing (which offers it a much lower-impedance, outside connection to the water), yoiu can guess what I'll do.

If you have a better solution, please let's have it.

KD3PC · Jul 16, 2012

kenn said:
Um, what? Do you speak from experience, or are you thinking out loud, like the rest of us are?

What is this "natural" shedding that is part of the boat design?

over 40 years on the water, a large majority of it on Chesapeake Bay where lightning is quite frequent. A mast and rigging provide a point for lightning to follow and a protection area within, see faraday cage. The mast is usually mechanically attached to a keel, foot plate or some such that is mechanically attached to the boat. The shrouds attach at the top or close to it to the sides, as well as two or more shrouds fore and aft. Those are typically attached to the boat at chainplates (on the sides) and fore and aft at the bow and stern. Again especially on small boats those are attached to the boat via strip of metal that is but mere inches to the water. Larger boats, similarly attach and will allow the current to jump to the water. or directly to the keel or engine and out the prop shaft

kenn said:
I do have an electrical background, and I've tried to stay current with the issue of lightning hitting boats, and the possibilities for protection. The common denominator of most solutions is that you try to offer an easy path from the masthead to the water, that will minimize injury to occupants and damage to the boat.

I am a master electrician, with a BE in Electrical Engineering. I am quite experienced in high current discharges, static chutes, radio and transmitting towers, ground fields and continuity issues (see megger)

The easiest path is the shortest, most contiguous path that will sustain current as well as ground path and pre-strike.

kenn said:
Referring specifically to our small trailer-sailor, real no-sh1t 100% effective lightning protection is prohibitively expensive and not justifiable. The preferred solution is to not be in the boat during lightning. But IF we are caught out in lightning, all we can do is to make it easier for lightning to get where it wants to go via the outside of the boat, while we remain a bit safer inside the boat.

agreed,

and I posit that the easiest way for the current to dissipate is to follow that more robust path of masthead, shroud, chainplate and jump to ground...multiple poorer paths will do nothing except explode when the current attempts to take that weak path and jumps to a more appropriate path.

kenn said:
If the choice is between nothing (which means any lightning hit will have to arc the last few inches to the water, and is therefore unpredictable; could burn someone or hole the hull) , and doing the chain or jumper-cable thing (which offers it a much lower-impedance, outside connection to the water), yoiu can guess what I'll do.

a chain with marginal continuity, questionable conductivity and a casual attachment, will offer nothing as far as conductivity of high current. Those links merely touching do nothing. Similarly a jumper cable with a large alligator clip is not a connection, it is merely a high resistance short, as will be the marginal connection of a couple of wraps of chain around the mast.

kenn said:
If you have a better solution, please let's have it.

There is NO full time, safe solution to a direct lightning strike. The current is going to ground as quickly as possible, and there is NO predictable path. You may comfort yourself with these actions, as well as those of the U FL expert...at greater cost, but they will do nothing to guarantee the path and how it exits the boat.

Maine Sail · Jul 16, 2012

Lightning also does not like to take sharp turns as it would connecting something to a spar then draping it over the deck. This near 90 degree turn can force the strike to jump.. If diverting away from the spar the more gradual the turn in the wire the better the chances of the lightning following it to earth. You also want at least about 1 sq ft of conductor below the water. This is why keels work so well. This is perhaps the best type of lightning bonding you can do if you have internal ballast.

This is a copper strip affixed externally..

When our boat was hit the first thing the surveyor looked at was our primary/secondary lightning bonding. Our hull sustained zero damage so we can guess the system worked as it was intended to work. The 2/0 GA wire between the mast & keel bolt was perfectly intact..

Contrary to popular misconceptions lightning "protection" is not about eliminating strikes, it is about making them safer. Lightning will hit what ever it wants to. Getting the strike to water with a direct low resistance path is the preferred method to protect the hull and minimize hull damage that could lead to a sinking. Jumper cables to SS is really a feel good fix, IMHO, that a lightning strike will simply laugh at.. Hell the massive jumper cable like clips on my 500A carbon pile load tester can't even handle the 500A for a few seconds without arcing so I replaced them with real battery lugs. SS is also a horrible conductor and the strike would prefer the aluminum spar as it offers a much better conducting path. Connecting to the spar above deck usually requires a sudden turn, not good.

The picture below happened to a boat a few hundreds yards from ours on the same night we were hit. We lost 25K in systems and electronics damage but our hull was 100% un-damaged but she is wired to better than current ABYC technical standards (TE-4) and on the lightning system the wire GA exceeds the ABYC recommendations..

This guy was not so lucky. The boat had numerous holes blown in the hull and took on massive amounts of water and suffered a near total loss.. The mast was not bonded to the keel and the lightning took the path of the spar and the VHF cable. The cable was run near the hull directly behind these holes and escaped through the hull near the waterline.

This boat had one of the shortest spars in the 1000+ boat anchorage and was not grounded thus blowing two "theories" right out of the water.

Theory #1 "short spars won't get hit when taller ones are around", this is simply an bogus old wives tale..

Theory #2 "un-bonding/un-grounding your boat will make you invisible to lightning" please don't do this as nothing could be further from the truth and there is insurance data that shown grounded boats suffer less strikes, not more...

kenn · Jul 16, 2012

Thanks for the detailed answer.

I am aware that larger boats are best fitted with complete bonding systems, leading hopefully to a reliable in-water point like a metal keel or a large conduction plate.

KD3PC said:
...I posit that the easiest way for the current to dissipate is to follow that more robust path of masthead, shroud, chainplate and jump to ground...multiple poorer paths will do nothing except explode when the current attempts to take that weak path and jumps to a more appropriate path.

My turn to posit (or is a counter-proposal a 'negit'?

). Most trailer-sailors have relatively high freeboard for their size, and the chainplates are high up, or even deck-mounted. Quite a path to jump. Second, our stays are often just 1/8" ss, which isn't that great a conductor... and shroud failure can be pretty catastrophic. So I'd much prefer to keep current off the shrouds and through the mast.

a chain with marginal continuity, questionable conductivity and a casual attachment, will offer nothing as far as conductivity of high current. Those links merely touching do nothing. Similarly a jumper cable with a large alligator clip is not a connection, it is merely a high resistance short, as will be the marginal connection of a couple of wraps of chain around the mast.

I hear you re the potential flakiness of chain or jumper-cable as a path, but even so... with the wet and ionization,it's still going to be a better path than the jump from chainplate to water, no?

There is NO full time, safe solution to a direct lightning strike. The current is going to ground as quickly as possible, and there is NO predictable path. You may comfort yourself with these actions, as well as those of the U FL expert...at greater cost, but they will do nothing to guarantee the path and how it exits the boat.

No disagreement, but we can still look for simple ways to reduce the odds of significant damage or personal injury.

Taking all your points into consideration, what would you then think of an arrangement similar to the jumper cables, using say #2AWG welding cable, where the connection to the mast is a high current quick-disconnect of some type, and the in-water end is a suitable sized copper bar or plate?

[edit after MS' post] - with the quick disconnects vertical, positioned on the mast maybe a foot above the deck to minimise the bend he points out[/edit]

walt · Jul 16, 2012

Something like this

http://zenpole.com/Zenpole_tech_picture_brochure_rev6.pdf

(project got stalled because of the cost of liability insurance required for licensing the patent from Dr. Thomson/ U of F)

Sumner · Jul 16, 2012

kenn said:
....Taking all your points into consideration, what would you then think of an arrangement similar to the jumper cables, using say #2AWG welding cable, where the connection to the mast is a high current quick-disconnect of some type, and the in-water end is a suitable sized copper bar or plate?...

One possible alternative for the trailer sailor is the ZenPole system (just noticed Walt posted as I was writing this)...

http://zenpole.com/

...if it comes to market. It is based on the technology mentioned in Rich's post on taking the lightning charge to the water's surface where lightning strikes in nature and not trying to dissipate the charge down in the water (which is real hard to do in fresh water). It uses electrodes that are designed with the trailer sailor in mind. Ruth and I had a prototype on our boat but luckily never got to test it. We have been in...

..... some really bad lightning on a couple trips though before having the ZenPole on the boat.

Here are some pictures and why we believe in it enough to use it ...

http://purplesagetradingpost.com/sumner/macgregor2/outside-43.html

... and like MS said these systems aren't designed to stop a strike and the statistics don't show that they attract a strike. They are there to hopefully lessen the damage, especially to occupants and to prevent holes from being blown in the vessel. I was going to go the chain or jumper cable route a year or two ago, but after reading felt that it would not do much, especially in fresh water where we are most of the time when on the Mac,

Sum

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onecoolair · Jul 16, 2012

Sumner said:
One possible alternative for the trailer sailor is the ZenPole system (just noticed Walt posted as I was writing this)...

http://zenpole.com/

...if it comes to market. It is based on the technology mentioned in Rich's post on taking the lightning charge to the water's surface where lightning strikes in nature and not trying to dissipate the charge down in the water (which is real hard to do in fresh water). It uses electrodes that are designed with the trailer sailor in mind. Ruth and I had a prototype on our boat but luckily never got to test it. We have been in...

..... some really bad lightning on a couple trips though before having the ZenPole on the boat.

Here are some pictures and why we believe in it enough to use it ...

http://purplesagetradingpost.com/sumner/macgregor2/outside-43.html

... and like MS said these systems aren't designed to stop a strike and the statistics don't show that they attract a strike. They are there to hopefully lessen the damage, especially to occupants and to prevent holes from being blown in the vessel. I was going to go the chain or jumper cable route a year or two ago, but after reading felt that it would not do much, especially in fresh water where we are most of the time when on the Mac,

Sum

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Our Endeavour 37

Our MacGregor 26-S Pages

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Sumner....Great posting I could have used that zenpole set up back in the day when I was sailing a j-24 then my mac-26. Back then we just did the best we knew how. And just to survive when the situation arose. We also prayed a lot. We pray even more now since 2008 the communist infiltration which seems to have taken over nearly everywhere I turn. The H356 I have been sailing for the past 10 years came bonded from factory. Thank you for not yelling....:cussing:

Maine Sail · Jul 16, 2012

Slow Mo^cean said:
It seems like a lot of the debate here is the worry about losing a chain or set of jumper cables to amperage overload. To me, I could care less if a $20 pair of jumped cables or chain gets smoked, as long as the lightning travelled through it instead of me or a family member on board. My biggest fear is the lightning travelling through a stay and into a chainplate, which is inches from somebody's head in the cabin..

Actually my concern is that it is a "feel good measure" that could likely still result in the lightning passing though the boat and finding an exit through the hull... A false sense of security might pose a greater danger than good. In order for lightning to follow something to Earth it needs good conductivity and it prefers a straight path. Chain wrapped around a spar or jumper cables on SS shrouds will not give a very good connection at all. As I mentioned my jumper claws won't even handle 500A clamping to soft lead let alone 30,000 amps +/- clamping jumper claws to SS shrouds.

I am more concerned about the false sense of security and I could care less about $20.00 worth of chain or a jumper cable.

I had a similar "false sense" event recently where a boat owner was using a zinc guppy. He measured its effectiveness by how little zinc had eroded. "had it for two years and it's still going strong". Sad thing is that his prop, shaft rudder shoe etc. were all toast. He never checked his shaft zincs, or measured his level of anodic protection because his zinc guppy gave him an incorrect and costly false sense of security. He had NO protection from the zinc guppy so never checked his prop & shaft zincs. Ouch $$$$$$....

Mark Maulden · Jul 16, 2012

A severe lightning strike is considered in the aircraft industry as 200,000v AT 200,000 amps. A 747 does pretty well at taking this kind of strike as there is a lot metal to go through. Even then, sometimes there are holes in the fuselage from direct hits. All electronics are well shielded which you're not going to do on a fiberglass boat. When lightning strikes, there is an initial attachment point to an "object" and there is an exit point on that "object". If you look at pix of aircraft strikes, it appears that it is being struck twice. Once up front and once in the rear ( or multiple). The aircraft (or boat) is simply part of the path. There is a video of a 747 getting hit out of Narita Japan. You can google it. The problem with using cables/wires to the water is that they will be blown off. It is not the magnitude of the current rather the magnetic forces (due to high current) that try to straighten the conductors out that blow them off. You can have the best connections, but if the conductors are a cirquitous path, they're not going to survive and current goes elsewhere.