Lightning-Are you Protected?

[Geminidawn]

Its typhoon season here, almost every day for the past two months I have seen lightning, for that reason I’m seriously thinking about getting the Pahi protected. After all a boat with a 50ft mast is likely to be struck one time in an 11.2-year period, rare it may be but looking back at the insurance claims it has happened to many. Sailboats are struck approximately 25 times more frequently than power boats and for some reason the odds are higher still for a multihull.

But it is not an exact science there is lots of homemade and ready to buy Lightning Protection Systems out there, but some are just as likely to attract lightning as they are to protect you from it.

Has anyone got any experience or ideas regarding this?

[Raf]

I've looked at this matter closely, as north Queensland is lightning prone over the cyclone season. My finding wasn't reliable nor incoregging. Some say, while a "grounded" boat might have some protection, it inevitably offers a shortcut for the bolt thus increasing the possibility of being struck. The grounding, to be reliable and discharge somewhat of millions of volts, has to be massive. A quick calculation from an electricity expert, suggests that, under the boat a copper plate of about one meter square should be placed in order of  dissipating the massive charge. also the connection to the plate should be big and run all the way to the top of the mast. Don't take this as correct, it's what someone else told me.

I do not take any precaution and so far, after 35 years of yachting, luck was on my side, and on my luck I will still rely. 

[Ricardo Aráoz]

I've always wondered about the size of these plates.... do they take into consideration that one side of it is not in contact with salt water but with wood that is isolating? Should they be double big?

And do they consider that plate will probably get very hot and the possibility of burning a hole in your bottom?

[Galway Bay]

Not something I really worry about - bit like being hit by a bus here - literature suggests that grounding the mast is only half [ or less ]of the answer as the strike is as least as happy to come down the shrouds... and lashed shrouds are probably not effective insulators at the voltages we are considering here. After all if it can jump several hundred meters through the sky what is a 10cm lashing ? Also grounds must be very very straight to be effective. Probably a ground from the bottom of the mast thro' 90 to the hull [ignoring the distance which is in fact a huge problem] then 90 to some plate is not an effective solution.

But hey I don't really worry - but for sure generating a conductive path encourages strikes. Some early experiments on elec. were done by flying kites on wire strings in strike conditions. Even today researchers trigger strikes by shooting firework style rockets - the carbon rich trail is apparently conductive and reliably triggers a strike...or so I am told....

Now I will get back to worrying about Gales and Fog etc.. with which I am more familiar...

[Geminidawn]

I'm thinking to go without. My biggest fear was not the masts but the 10mm Norselay shrouds, knowing that lightning takes the path of least resistance having those shrouds that high on the boat was like ringing the dinner bell for a lightning strike.

I'm opting for Dyneema shrouds instead.

The second greatest lightning conductor would be the VHF antenna. I'll just have to get into the practice of disconnecting it and stowing it somewhere safe during thunder storms. 

[Geminidawn]

That's all very well if you're sailing, statistics have shown that a boat in motion is less likely to get hit. Most hits however happen when the boat is moored or anchored.

Disconnecting your VHF antenna will save your radio getting fried but care has to be taken where you place the connector. I read one account where the owner did just that but left the connector dangling down. When lightning struck it travelled down the cable and exited through the nearest point blowing a hole through his fibreglass hull, luckily the whole was above the waterline.

[steve martland]

try a condom over your vhf antenna.. they protect against a myriad of other things ..maybe lightning too.. otherwise you can pray to the god of your choice that lightening doesn't get you before the bus does.................

[Ann and Neville Clement]

Steve,

We have wooden masts, the ss shrouds come down to wooden deadeyes which are threaded with rope lacings.  So the lightning may hit the masts and try to travel down the shrouds, but it cannot get beyond the deadeyes and rope lacings. 

We have had one experience with St Elmo's Fire in which there was a ball of lightning rolling around in the foredeck.  This was during a huuge thunder storm and, as usual with St Elmo's Fire, there was no damage. 

My understanding is that once a boat has been visited by St Elmo's Fire, it is protected from lightning.  My dad was head of the Electrical Engineering department at Caltech and he and his uncle (who had the Nobel Prize)  were quite interested in lightning.  They spoke about it a lot and I learned that thre is much speculation re lightning and not much that is settled scientific fact and this is especially true re lightning protection back then and also today.  So for the present, we are going with St Elmo and are grateful for his visit.

Ann and Nev

[steve martland]

sailed around the world many times on ships with big steel masts poking into many a thunderstorm.. no strikes  .. ask Thor to be kind.. and wear a condom for luck?!

[Raf]

talking to many seasoned seafarers and all seems to agree, the chance of being struck at sea is minimum. Perhaps because a vessel at sea is actually a hurdle rather than a conductor for the bolt to reach the water. Those very few incidents known in the gossip range, are damages to the electronics. 

[Rogerio Martin]

WE PRAY...

[steve martland]

PSP  for short  ;-)

[Ricardo Aráoz]

LOL

Actually I've heard the best prevention is leaving your radio home. Probabilities of being struck go way down and battery consumption goes down too.

As a matter of fact, they say unstepping your mast and staying home will also help with lightning prevention. ;-P

steve martland said:

PSP  for short  ;-)