Don't Want to Be BBQed by Lightning

[canucksailor]

I had a direct hit in St. Augustine FL while aboard, using the computer with the puppy beside me. Everything went white, the 'BOOM' was deafening, the computer went dark.
I realized what happened and instinctively checked three things. First, I lifted the puppy's tail to make sure there was no mess underneath her. Then I looked under where I was sitting, same reason. (It was a REAL LOUD BOOM!) Then, I checked the bilge for water coming in. This three step process is now my standard protocol for a lightning hit if (God forbid!) it should ever happen again.
Lost all my electronics, including my Airex. Shattered and/or blew several fuses out of their blocks on the electrical panel. My starboard nav lightbulb, the filament was vaporized and it silvered the inside of the glass. Simply amazing to see this. Port side, nothing wrong.
Unfortunate thing was that I'd added most of my electronics less than eight months previously. Ham radio, charge controller for the solar, the airex, plus replaced the VHF radio, depth sounder at that time.
The strike also vaporized about two thirds of my antenna at the masthead. Three pieces of hot metal burned small holes through my brand new bimini canvas. The windex? What windex? Gone, all but the base.
About a year or so later, the alternator quit and the reefer. No idea if these were also caused by the strike weakening something in them. Probably not, but you gotta wonder.
That I have read, there really isn't anything that can prevent a strike. However, I now disconnect the VHF antenna while there's a storm in the area.

[zeehag]

dang!!!!!! i place a stew pot over the gps after unplugging it..lol

[ozskipper]

Originally Posted by zeehag

dang!!!!!! i place a stew pot over the gps after unplugging it..lol

Improvized faradays cage. Something those steel yachties have over tupperware sailors.

My inexperienced trick would be to keep the deck as wet as possible. and toss some chain or heavy wire into the water. Of course I would connect the chain to the side stays first. In the hope that as much current would pass on the outside of the boat should the boat be struck..

I remember in an asa newsgroup years ago where one member had lost all electronics on her boat even though the strike was on the other side of the marina.

I guess its a good reminder on how much we still need to keep a sextant handy on blue water passages.

Cheers
DP

[zeehag]

i was told to throw a set of jumper cables over the rail from shrouds(make sure ye connect them to the shrouds first before throwing..LOL) to into water..havent tried it yet--- seems to be a quicker access to the boat by the scary stuff.....

[ozskipper]

Jumper cables = good idea. Would need a few sets, but a quick solution all the same
Cheers
Oz

[svtrio]

You can drill and tap the mast base and run a heavy cable directly down to the cockpit and through the cockpit floor (use a cable seal device) to the nacelle bilge. Avoiding sharp bends, you can route the cable to your single-point ground in the engine compartment. A more direct route to ground may be better.

A copper/bronze strap can be thru-bolted outboard port or starboard with bronze bolts on the nacelle beginning below the mast and run aft to the stern. Attach the cable to the nacelle strap directly beneath the mast, which allows for the most direct flow of current to ground. This strap can also be used for single-point grounding.

On the Prout 34/35s I have seen (including mine), the section of the nacelle below the mast is likely to be in the water, but if not, the strap running farther aft will be in the water.

Roger

[NotQuiteLost]

I was sailing through a typhoon last year, and woke up to the aforementioned BANG to find every single fuse on the boat blown and a nice little mark on the top of my mizzen mast. My radar didn't work any more and there were some other things that I can't remember off the top of my head.

Being steel-hulled limited the damage, I'm guessing. I actually only 'lost' the radar, and it turned out that it was only a small melted section of the wire which was easily repaired (and a fuse, of course).

Fairly amazing, just how little damage was done. A couple hours of testing all my electrical lines to key systems, replacing the blown fuses and re-testing everything is pretty much all it cost me.

[MoonlightShadow]

My Ex says I will not get struck. She says I have never attracted anything in my life.

[Mark Johnson]

If you live aboard and cruise in areas that have a LOT of thunderstorms, like the US east and Gulf coast, (or god forbid, PANAMA), and you do it as a lifestyle for 30 years, your odds of taking a direct strike over that time are about 40%. I've had minor damage on numerous occasions, because the boat 200' away took a hit! Luckily I have not myself. I have, however, talked to more than a dozen folks that have been hit!

The most basic level of protection is to have a pointed "lightning rod", (the bottle brush type MIGHT help)... and a "00" size wire from the mast base, straight as possible to a long narrow copper plate of at LEAST 2 sq ft., on the outside of the hull. This alone should keep the mast from being driven through the bottom of the hull.

The next level, if you want to go there, is to tie in all stays and shrouds with #6 wire, and large metal, like the engine and oven. (to protect occupants from side strikes)

The next level to try to save a few electronics, is between too impractical and too much work...

The idea is to let the lightning get directly to ground, without exploding your boat.
These basic measures are right up there with gravity, as far as being more than "just a good idea"!

Properly grounded boats are NOT more likely to be hit, only more likely to survive...

Mark

[zeehag]

Originally Posted by Mark Johnson

If you live aboard and cruise in areas that have a LOT of thunderstorms, like the US east and Gulf coast, (or god forbid, PANAMA), and you do it as a lifestyle for 30 years, your odds of taking a direct strike over that time are about 40%. I've had minor damage on numerous occasions, because the boat 200' away took a hit! Luckily I have not myself. I have, however, talked to more than a dozen folks that have been hit!

The most basic level of protection is to have a pointed "lightning rod", (the bottle brush type MIGHT help)... and a "00" size wire from the mast base, straight as possible to a long narrow copper plate of at LEAST 2 sq ft., on the outside of the hull. This alone should keep the mast from being driven through the bottom of the hull.

The next level, if you want to go there, is to tie in all stays and shrouds with #6 wire, and large metal, like the engine and oven. (to protect occupants from side strikes)

The next level to try to save a few electronics, is between too impractical and too much work...

The idea is to let the lightning get directly to ground, without exploding your boat.
These basic measures are right up there with gravity, as far as being more than "just a good idea"!

Properly grounded boats are NOT more likely to be hit, only more likely to survive...

Mark

as re the properly grounded boats bit-- tell that to the NASA engineer in slidell whose bendytoy 50+was hit 2 times in 4 years....i believe the second time the damage was also up the wiring to inside the house from the boat. i found that humorous, yet tragic, AS HE BELIEVED HE WAS PROTECTING HIS BOAT.. poor guy--

[Mark Johnson]

Properly grounded boats are simply "less likely" to have the bolt jump from the mast, and go through the hull, or even have the mast driven through the hull! They can and do get hit! Hopefully with survivable results. Since the power of lightning strikes varies by 10,000%, so does the damage.

By far the safest boat in a lightning strike, is a properly grounded but insulated metal hull. It can dissipate the charge the most effectively, and they tend to have the least damage. For the rest of us, we just do what we can... or do nothing. It is a personal choice.

Like all things cruising, and ultimately in life itself, all we can do is stack the odds in our favor... There is no absolute safety, only postponement.

Mark

[North26West80]

I live in south Florida which is the most lightning prone USA state. After considerable research and thought, I decided to put a 3' lightning rod at the top of the mast and 1" tin coated copper cable from the mast to a bronze ground plate directly under the mast. The strategy is, lightning will hit where it wants and all I can do is give it free passage to ground. The boat has never been hit despite hundreds of nearby strikes, but the power lines on the adjacient street were hit once and the surge down the dock power took out the charger/inverter and galvanic ground isolator on the boat and a few electronics in the house.

If you decide to be proactive about this, the two things I would advise are; 1) Focus on the path of least resistance which is down the aluminium mast and into saltwater. Aluminium is a great conductor, so just complete the path to a external ground plate. I added a lightning rod to hopefully minimize damage to mast top lights, etc. Stainless steel rigging on the other hand, at these voltages and current is a very poor conductor so don't count on rigging for anything. Just connect it to your ground plate to reduce the shock hazard to people nearby but 99% of the lightning strike wil go down the mast. 2) A rectangular ground plate has more perimeter per square foot than a square ground plate. So the theory goes that the electricity is dispated at the edges of the plate and so more edge is better. I don't know this to be a fact, but I was once an electronic engineer and the concept makes sense to me. Mine is 4" x 36" and I used bronze instead of copper because I thought it to be more compatable with other underwater metals and only slightly less conductive.

Like I said, I did a lot of research before I adopted the above strategy. I found it very difficult to even find a source for aluminium lightning rods, heavy gauge wire, bronze wire fittings and a bronze ground plate. Even finding bronze bolts is hard these days. I considered starting a business supplying these things for boaters, but as you can see by the gallows humor in previous posts, most people don't take this seriously.

[zeehag]

WE SAILED THRU THE GOM FOR NEAR YR OFF FLA IN LIGHTNING STORMS FOR DAYS AT A TIME APPALACHICOLA-- ENTERED SURFING 6 FT SEAS FROM SEVERE ELECTRICAL STORMS BUOY TO BUOY. YES I TAKE MY LIGHTNING SERIOUSLY . I TAKE IT SERIOUSLY ENOUGH TO KNOW IT IS RANDOM AND YOU CANNOT PROTECT FROM IT.
i wAS NEAR HIT At AGE 3 ..YES I TAKE MY LIGHTNING SERIOUSLY.L I HIDE UNDER A FELINE. I WEAR CROCS. I WEAR RUBBER SUIT. I WEAR GLOVES
LOL. I PRAY TO SEA GODS. I GIVE OFFERINGS TO SEA GODS.
I HAVE YET TO BE HIT. KNOCK WOOD.

[GordMay]

Originally Posted by Mark Johnson

... The most basic level of protection is to have a pointed "lightning rod", (the bottle brush type MIGHT help)... and a "00" size wire from the mast base, straight as possible to a long narrow copper plate of at LEAST 2 sq ft., on the outside of the hull. This alone should keep the mast from being driven through the bottom of the hull...

... Properly grounded boats are NOT more likely to be hit, only more likely to survive...

Mark

Well said Mark.

It’s worth noting that Blunt or Rounded Tip Air Terminals (lightning rods) have been shown to be slightly more effective than sharp pointed Lightning Rods, because they have lower breakdown voltages, and longer time to breakdown compared, to other air terminals.

➥ http://journals.ametsoc.org/doi/full...-0450-39.5.593
http : //journals.ametsoc.org/doi/full/10.1175/1520-0450-39.5.593