Lightning

[Ozzie]

http://www.sailingworld.com/boatingsafe ... ing-strike

Yet another spiel on the subject . Once again the protective cage. Experts disagree on just about everything. Thats why they are experts. Take it all as you will. Best advice is still to POQ.

[Andrew]

Looks like complex motor boats in the article, i wonder how investigators would go? I suppose stay home if electrical storms forecast. If caught out in an electrical storm presume staying in the cabin would be the best chance. If on land inside the cars or house the safest spots.

Had a few scrapes with lightning at work in the great outdoors. So looked into it. Discovered that lightning can travel along way horizontally from its source, if you hear or see it, it could potentially reach you. Stay away from anything conductive, stay dry, wear rubber soled footwear, keep a low profile, take cover inside something not below a tree (or mast?). On one cruising yacht i sailed on, the professional skipper shackled a linked chain to the shroud and tossed the other end overboard into the sea to act as the earth wire.

[Yara50]

The chain connected to the rigging and dangled overboard is the classical lightning conductor technique. Bit of hose around the chain at the points where it touches the hull would help preserve the gel coat. It is rare to hear of a moored yacht being hit by lightning, as most have a length of chain over the bow roller, hopefully touching the forestay chainplate, and providing the conductor earth. Even a wet rope will help do the same thing.

[Andrew]

That's good news to hear, sounds like its pretty safe with that set up

[Bobbo]

I have just logged on and read this thread. It's a subject of extreme interest. I was anchored one night with a greasy swell and was woken at 02:00 hours by the loudest thunderclap I have ever heard. It had me out on deck before my eyes were properly open. The lightening flashes and thunderclaps were simultaneous. I had a seven Kg CQR with ten metres of chain and 21 metres of 12mm nylon out (2 metre depth at low tide, 4.2 range) The wind gusts were estimated at over 100 ks and blew the roofs from a couple of home in nearby Mackay. The wind tore my stopped jib loose and the anchor dragged. I had waves breaking over the deck. It was a very hairy time...and all the time those simultaneous flashes and booms and the tallest thing around was dear little Zoe Amelia's mast
I had read of the chain from the shrouds technique but I certainly had no time to deploy it and I'm not sure I would have liked to given the circumstances.
I am not carping here, but genuinely searching for wisdom.
After that episode I searched the WWW for information and the best I could come up with is that opinions differ!
Given the potential energy of a lightening bolt and some of the anecdotal evidence I have heard and read I honestly don't know what to think.
Personally, given the fact I am in my late seventies, I have simply decided not to let it worry me...Somethings gotta get ya and being zapped in my little boat beats ending up in an old peoples home hands down...but this is small comfort for those with families aboard.
It is of little use to advise people to stay home: no one saw that nasty little tempest coming, and it was gone in an hour with the winds going through 360 degrees before it rumbled away down the coast.
So what is the conclusion" I don't know! I certainly don't have one. If I suspected an electrical storm was likely I actually used to clip an insulated welding cable to both shrouds with a couple of vise -grips. The lower 500mm stripped of insulation and submerged by a metre into the sea. On the few occasions I did this we did not get a storm. Since the episode above I have been told that making a conductor of the mast may well attract a strike.
I would love to hear opinions on this.

[Yara50]

The theory is that by earthing the mast, you provide a route for static charges in the local area to dissipate before a strike happens. The strike then would prefer a route with more static charge. If that fails and you do get a hit, the current would still prefer the path you have given it, rather than through you. However, I would not sit too close to the rigging in a storm- the lightning might not have read the theory!

[Bobbo]

Yes. The theory seems sound...but!?....I have seen photographs that imply that a strike is first presaged by a tiny little feeler first going UP, as if to say "Pick me! Pick me!" ( a bit like a politician at election time, with similar devastating results once the choice is made) It is on record that mining areas, with their wealth of carbon deposits, cop more strikes than is usual elsewhere. I have this uneasy feeling that by offering a clear path via chains from the shrouds we just might be inviting a visit; and that visit may involve more current than we bargained for.
I heard a scary story of a wooden boat at anchor where one of the crew did not come on deck for his dinner; since this was out of character they went looking for him and found him dead in his bunk, unmarked except for the imprint of the chain plate ( which was eighteen inches away) burned into his temple. This is hearsay and may, or may not be true, but you have to admit it is a striking story The point was that nobody registered a lightening strike and there was not a cloud in the sky.

[Ozzie]

http://edis.ifas.ufl.edu/sg071

Came across this site while reading boat stuff on the weekend in front of the fire . I'm afraid all my stories to friends about how the "best sailing is in winter" have gone to hell on a hand basket this year and hell has frozen over ......I must be getting old.

Anyway, this article above, while clearly very academic in nature is the best 'understandable' ,to me at least , article on lightning relevant to sailing vessels I've come across. It also explains very clearly what thunder is. Interesting in that, as I see it, stainless shrouds are not as good as the mast for grounding. You are better to have suitable cable from your mast base wired to your lead keel. The GRP encasing your lead keel in not an issue in salt water.

So reading this relevant to the Investigator , if you ran a heavy cable from the mast proper to the steel lift handles on your lead ingots in the keel you are some way towards a good grounding. Also note the bit about lightning jumping up from your boat, which we knew. This means, as they state clearly, that grounding your boat does not make you more likely to draw lightning to you.

Oh and most important if you are in a storm disconnect the mast head light plug if you have one. It's just an extra convenient way for a few billion volts to toast your electronic goodies and your toes.

[Ozzie]

Bump.

Just rereading some old posts and I thought this was worth a bump to see if anyone has any further experience with lightening or new knowledge on preventing it from toasting your oats ...while you’re eating them.

Gee...2014... back when the only solar panel on the boat was connected to the battery instead having one on my head

[Peter T]

Ozzie, you mentioned about connecting from the mast on an investigator to the lifting handles on the lead ingots in the keel.
As I see it mate there is a problem with doing this and that is that the lead ingots are insulated inside the fibreglass of the hull / keel and if lightning struck the mast, it will travel via the lowest resistance path to get to earth. If this happens to be from the mast, through the connection from there and to the lead and then through the fibreglass of the bottom of the keel, it could very easily actually blow a hole from the lead through that fibreglass which would then allow water to enter the boat. This might not be a problem so long as the lead is well sealed above the lead. I know that I don't want water in my lead compartment ever again so if it was me, I would have a chain or similar from the mast, over the side and into the water and do everything possible to not allow a hole to be blown through the bottom of the hull
I might be wrong mate but that's how I see it.
Cheers