LIghtning proof

[Ross]

TonyB, I am afraid that RossB has you on this one.

It all has to do with the voltage involved. At low voltage and high current the entire conductor serves but somewhere above 300,000 volts the current flows on the surface. I saw a power transmission line made up of 6 conductors with spacers for each leg of the line. From the insulator count I would guess it was carrying in excess of 600,000 volts.

 

[Chris Burti]

I'll go with the "insurance" crowd.

I can relate my experience for whatever that may be worth. We sail in an area prone to sudden summer squalls that are often accompanied by high winds, driving rain, hail and lightning. Enough experience with these squalls makes you just comfortable enough to forgo putting on the Depends with your foul weather gear but still leaves you as nervous as fox running with a pack of hounds.When we see a squall line approaching, we drop and secure all sails and lines. Assuming that it will miss you is a sure invitation to be wrong. These squalls usually pass quickly and wind direction will reverse itself. You can expect gusts over 40 knots which can lay you over to 30 degrees under bare poles and will knock you flat if your main is up and sheeted in. I rarely anchor since dragging is so very likely, though many other skippers do. For these reasons I'm usually at the wheel when the bottom drops out. 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 friends Sabre 37 while he the rest of the crew were down below. I saw a bright flash, but didn't notice much sound. The crew later reported hearing a huge boom, 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 was "Dumb move, Cap'n Stupid...too late now!"Insurance (less the deductible) took care of the VHF whip, Wind sensor and Windex, all of which were vaporised, the haul and survey for hull damage (none), and replacing the instruments. The only thing wrong with the instruments was the SeaTalk capability was fried.Got hit at the dock last year on our boat, but we were not aboard and it must have been a collateral strike from nearby because all it did was fry the VHF, the electronics on the charger and the SeaTalk on the instruments...didn't even make the deductable this time.The only other certain option to avoid lightning is to stay at home in the Summer in this area.

 

[Ross]

I was talking with a home owner years ago

about lightning protection. he told me that he had formally asked his insurer if having lightning protection on his house would reduce his premiums. The asnwer was a solid NO because the risk of a given structure being struck is so small that they can not quantify it.I have considered the value of insurance versus the cost and I believe that the cost of premiums for an older boat are better invested in the equity stock of the insurance company.

 

[Ross B.]

Walt; I'll have to look them up again

A couple were from links I found on this website, but I did not bookmark them for future reference. Here is one with damages assesments between the two. When I locate the others again I'll post them. I remember the numbers but you may be right on one point; the articles may have been referring to all boats, not just sailboats. It probably evens out in the end if you figure our 365 day a year probability of lightning storms here compared to yours rate in Denver. I'm sure the statistics were calculated by single event methods, not reported totals for seperate regions.

 

[walt]

fresh vs salt

Ross, thanks for the link. Regarding fresh vs salt water:I think what you will find is that generally damage to boats in fresh water is higher than in salt water from a lightning strike. The "1000" number Ive seen refers to the disolved mineral content difference between fresh and salt water and the disolved mineral content aids in the water conductivity. But I dont beleive it has much to do with your chances of getting struck and we could discuss that.Here is what I got in the referenced paper (Dr Ewen Thomsons IEEE paper from 1991)The survey was done on 71 boats total which had been struck by lightning. 44 of these boats were in salt water and 27 were in fresh water. We really cant conclude anything about the occurance rate of a strike from fresh to salt water from this (61.9 percent were in salt!) since we dont know how the data was collected. However, the survey does show that boats in fresh water had a higher percent major hull damage than in salt. These numbers are:Salt water protected boats major damage 2 out of 28 or 7%salt water unprotected boats major damage 3 out of 16 or 19%Fresh water protected boats major damage 6 out of 15 or 40%Fresh water unprotected boats major damage 9 out of 12 or 75%Note: I do most of my sailing on a lake in Colorado at 8600 feet that is not that far from where the snow melted. So at least I HOPE Im not 1000 time more likely to get hit!!!!