My wife asked what happens if you get struck? I have always had a heavy copper cable clamped to back stay with shaft zinks attached. When lightning would be around I would drop the cable. My old boat got struck twice on the Ankor with no one aboard it took out my entire ele system cooked my battery’s and so on.
HI James, we got hit by lightning in 2012 and we were on the boat. It was 4 am and we were anchored just north of Christian Island in Georgian Bay. The insurance company paid for all costs without blinking. Hard to fake a lightning hit.
The safe areas on the boat turned out to be the forward berth and the main salon. There was evidence of scorching below the floor boards, in the lockers and in the cockpit. Anything that had a circuit board was fried. This meant all the electronics were out starting from the vapourized antenna, refrigeration, air conditioning, auto pilot, Espar heater, GPS, engine regulator, all instruments & radios, etc.
There were 41 pin holes in the hull & rudder but in the end the hull and rudder proved to be sound as per the surveyor. I had a lightning master at the top of the mast which proved to be worthless. You can put a copper cable overboard and that might help some. Just remember that you have to get rid of something in the neighbourhood of 30,000 amps! Just not doable without damage.
After the repairs the boat was totally updated and better than new. Unfortunately it took me 3 months to rip everything out and re-install. Meanwhile the yard sand blasted the hull and applied 3 coats of epoxy and VC17.
Ron & Diane Schryver
“Alpha Waves” 1987 NS30U #393
Georgion Bay Midland ON
P.S. We now have a wooden wheel and in a storm I use the autopilot with a remote.
Also remember lightning is a “high frequency” event, as described to me by an amateur radio many years ago. Ron seems to have described this perfectly, from his personal experience.
Carl Linkinhoker
NS26C, 146, Break of Day
Mayfield, NewYork
James
Would having the copper cable overboard be a good idea when not on the boat too?
James B
Jack , the answer is yes . I would take it up when not in use because when you were sailing the speed would hold it off the transom, so at Ankor it would chafe the transom so I would roll it up unless it was a storm. Hindsight you know. I am just wondering if installing a Dino plate and a heavy ground wire is needed or is there something all ready in place? Jim Moores n33-41#. Arawak
James P. Moores
Guys:
I don’t profess to have any electrical engineering expertise, but it seems to me that, if you mount a mast-top lightning rod (or radio antenna) on top of a conductive aluminum mast, then ground the thing directly to the ocean with a big copper cable, you are doing everything you possibly can to lure any lightning to strike your particular boat in a harbor or mooring field of other less alluringly grounded boats, just like old Ben Franklin did with his kite!
If you are the only boat out sailing alone in a thunderstorm, your mast, whether grounded or not, might take a strike. The question then becomes how much better you would fare with a designated grounding pathway.
The average lightning bolt carries about 30,000 amps, but a large one can have up to 120,O00 amps and transfer 350 coulombs of energy.
I intend to query some of the experts like Nigel Calder on this subject. Surely, the various boat designers have made efforts to mitigate this problem in various ways.
Barry Stott
Chadds Ford, PA
ebstott@aol.com
Would love to know what Nigel has to say. Please report back!
Back in the mid 80’s I worked for a local marine electronics dealer. We were the Micrologics, B&G, Signet, and Trimble dealer/service center before internet buying became popular. A local sailor with a Lancer 28 was struck 3 times. Twice on his boat and once on the elaborate weather station he had mounted on the roof of his house. After the 2nd hit on the boat he carried jumper cables with him. If a storm popped up he would clamp them to the upper shrouds at the chainplate and drag the other end in the water. As far as I know he was never struck again but not sure if that had anything to do with it.
Thank you,
Greg Doyal
NS30U #516 Challenge
Grosse Pointe, MI
Since we don’t have stays or shrouds we don’t have a convenient place to clamp a jumper cable. Having the second tallest mast in the harbor, this has always worried me a little.
Tim in STL
White O’morn NS26U
Harbor Point Yacht Club
West Alton, MO
I think that I would choose not to sail nor live near him.
Joe Valinoti
S/V iL Gatto NS30U #221
Sea Harbour YC
Oriental, NC USA
One advantage of shrouds and back stays is they may act as a Faraday cage of sorts.
I suspect that the idea that we could have a conductor and circuit capable of transmitting 10s of thousands of amps, driven by extremely high instantaneous voltage, to the water without incurring damage is highly unlikely.
Now for my theory, and I understand you may find this amusing rather than helpful😊. Full disclosure, I am not an electrical engineer so please treat my theory accordingly.
I suspect the main purpose of the heavy gauge cable between the keel and the mast has more to do with dissipating static electricity than carrying the energy (Joules) in the lightning safely to the water in the event of a strike. No doubt the grounding circuit should help dissipate some of the power (voltage times current) in the strike. But I suspect the circuit’s main purpose is to prevent a strike from happening in the first place.
A large gauge conductor creating an electrical circuit between ground (the water) and the mast along with anything connected to the mast, removes most of the static charge that could develop in that physically tall circuit. The presence of static charge opposite the charge in the storm leads to a strike. This circuit effectively brings the top of the mast, electrically, toward water level. The wish bone and hull might still accumulate charge and therefore attract a strike. But the threat is reduced by the grounding circuit. Which means that our masts are not necessarily, and electrically speaking, the tallest objects in the marina.
Like many of you I am sure, we have been caught in intense electrical storms out in open water. Gratefully we have been spared; so far. And our yacht club has been in the centre of far too many electrical storms to count. I do not recall any boat at out club being hit by lightning. I think the reason for that might have something to do with boats having grounding circuits to minimize the likelihood of a strike.
Our boat has a large ground cable that connects the forward keel boat to the mast step and therefore to the mast. I check the connections each spring. If in the event of a strike, like Ron and Dianne experienced, there will be damage. With high potential for injury. Ensuring a sound and robust circuit from the keel to the mast should reduce the risk of a lightning strike. There is no such thing as zero risk, but we can mitigate the risk.
Anyone care to debunk this bit of internet fake news?
…..Ed
Ed and Marlene Brost
SaSeaCat N30U #322
Sarnia Yacht Club
Sarnia Ontario
I should have proofread my submission before pressing send. The following is a corrected version. Sorry for littering your inboxes.
This is absolutely not my area of expertise, but I’d be concerned that a connection from the mast to a keel bolt would damage the keel attachment in the event of a lightening strike. That would not be fun.
I thought that the practice was supposed to involve attaching to a grounding plate under the hull rather than a critical structural element.
Again, not an expert – despite the lack of question mark, I’m asking a question rather than stating a position.
Echoing the plea of others, would someone with expertise on the topic, please chip in?
– Bob
Solar Wind
Nonsuch 26C, #143
Thank you Bob,this is important to the safety f all us. Jim Moores N33-41# Arawak
Sailors
Came across this article and web site for those of you interested in the lightening issue. It’s seems the Florida professor knows as much as any one on how to reduce risk. Notice Nigel mentioned in the story.
http://www.oceannavigator.com/May-June-2013/Lessons-in-lightning/