lightning

I was out sailing my Hobie 14 this weekend and was having so much fun that I stayed out way too late in an approaching thunder/lightning storm. Got me thinking about lighting on the Hobie.

Ive been windsurfing for 20+ years and have also windsurfed in lightning storms a fair amount (in Colorado during the summer, its sometimes the only planning wind you will get) and over the years have heard of four cases of lighting directly hitting a windsurfer. In all four cases, the lighting went down the mast (usally 30 to 100% carbon) and then "jumped" to the water though the board where the mast attaches. The board is a very good insulator (styrofoam with glass skins) so that the lightning energy jumped maybe 4 to 10 inches through the board. The rig is usually damaged pretty badly but the guy sailing might have some burns on hands and feet (dont have good details here) but I dont thing anyone has ever had serious injuries.

The example of the windsurfer is very interesting because it would apear that a tall conductor that is still insulated from the water but that has conductive portions fairly close to the water has some data to support that it will protect a shorter object (ie, the sailer) nearby. The fact that the tall conductor (mast) is not grounded would also apear to be a good thing as it is not as good as a grounded lighting rod at generating "loss leaders" which is a charge flash comming up from the ground which meets the charge comming from the sky. So the non grounded mast is less likely to get a strike than a grounded mast.

If what is said above is correct at all (and it may not be...), I think the Hobie cat (at least my 14) is also pretty good for lighting. The mast makes a very low impedance contact with the aluminum frame and the frame has tubes which go down into the hulls. When sailing, the aluminum tubes are probably inches from the water and there are four of them. So I think there is some chance (once again, pure speculation here) that if the boat did take a direct hit, the energy would travel down the mast, into the frame, down inside the hulls and then jump to the water. The sailer would more than likely experience a fairly big shock because of the electric fields generated and maybe would get some burns (and would have the do-do scared out of them) but would probably come out of the event mostly OK. The energy is going to want to follow lowest impedance paths and the sailer is likely not one of them.

So are there any cases of lighting stricking a Hobie known?

Finally, when I did go back to shore, I took the sail down in anticipation of possible high winds and during that time, I was standing in or near very shallow water and my body was very close to the mast. During that time, I may have had a very high risk of getting fried if there was a lighting strike...

Note: the above could all be incorrect - use your own judgement when it comes to lighting!!!!!

One thing to keep in mind with lighting is that is is not very predictable. You can get a good idea of what it will do, but I would not bet my life on it. The only reliabel answer I can give anyone is if your body somehow becomes part of the path of least resistance for the lightning, you will not be a happy camper... if you survive. Your survival depends on many variables.

There is no sailing worth dying for. I would much rather cut one day of sailing in great conditions short than risk never getting to sail again.

_________________
Nick

Current Boat
In the market
Previous boats owned
'74 Pearson 30
'84 H16
'82 H18 Magnum
St. Louis, MO

Darwin award waiting to happen...

Hmmm - OK, Im back from the "show off those boats" post.

Sailing in lightning is simply a bad idea. However, in my post is a question - in the many years of Hobie cat sailing, does any one have "case histories" of what happened when a boat similar to a Hobie 14 was stuck by lighting while sailing?

Ok, now its back again to the "show off those boats" post.

I used to work for an electrical contractor, and would hear stories of electricity shooting up wooden shovel handles when a guy accidentally hit an underground electrical service. So the idea of having the pontoons insulating you from the lake sounds unreasonable to me.

I personally would never sail in a lightning storm. Think about it, a mast is essentially the same thing as a lightning rod, and is by far the highest point on a lake. If lightning were to strike the mast I wouldn't want to be anywhere close.

Personally if I were caught in an electrical storm I'd get home ASAP if the storm was far enough away, if it were close I'd turtle my boat and wait it out.

I think Nick is right, lightning is unpredictable, and is a huge amount of energy. It's definitely not something I'm willing to risk my life with for a few more hours on the lake.

Think about it, Mast sitting on frame you sitting on frame tiller in your hand (most likely wet), tiller hooked to rudders metal frame in water. Your the fuse. Even with that if it can jump from the sky to your mast it can jump the foot from your butt to the water.

That actually raises a great question...

What is the best thing to do when caught in a thunderstorm (assuming you can't readily get to shore)?

Obviosuly I'd be trying to get to shoe as quickly as possible, but I've also been on land and been right in the heart of a storm, with lighting striking all around me. Then I was in the forest so I got into the biggest nearby clearing and wet my pants (not part of the proceedure, just a reaction )

I wouldn't want to get into the water, but there is no scientific basis for that.
With no other information, I would lower my mast (I have a Wave, it's easy to do) and then wet my shorts

Some years ago, a keelboat was moored at a popular spot called Pinney's Point, three miles upstream from our Club. Lightening struck the mast, travelled down the mast and the shrouds, and took the 'shortest' path to earth. This meant that the electrical discharge flowed through the fibreglass hull into the water.

Fibreglass, despite any manufacturer's best efforts, contains zillions of microscopic air bubbles. These air bubbles become superheated when this kind of electricity passes through, and that caused the bottom of the keelboat to melt and blow outwards. The boat sank in five feet of water, no injuries as no one was on board.

Anyone got any 'war stories'? Hope not, for their sakes.

So at our Club, the First rule is 'don't go out.'
Second rule, if some horrible black cloud suddenly arrives, spouting bolts of lightening, capsize the Hobie, and hope that there are some keelboats around with taller masts.

If you want a story about us and the H16 being lifted into the air as a storm front passed through, we can show you the scars.

_________________
2015 H16, with spin,
SOLD 1989 Hobie SX18 Sail # 1947 "In Theory..."
'Only two things are infinite, the universe, and human stupidity. But I'm not sure about the former.'

John, your story is exactly the type of thing I am hopeing for - real case history.

The small Catalina keel boats (such as the Catalina 16 and I think the 18 also) have a set up that I think also might be good for "lightning resistance". The mast sits on the deck which is fiberglass and it and the shrouds are electrically isolated from the water. However, directly under the mast and inside the cabin is a metal bar that supports the mast at the top and is connected to the lead keel at the bottom. Im not sure if the metal supporting bar is electrically connected to the lead keel or not.

Once again based on what happed with the four windsurfing cases Ive heard of (which happened in NM USA, Florida USA, the other two somewhere in Europe), I believe a lighting strike to the mast of the Catalina keel boat would have the energy go down the mast, jump to the metal support bar, then jump to the lead keel and dissipate in the water. It would generate electric fields which would fry the electronics but its possible that people on board the boat would be unharmed - which is a good thing as you cant just simply run a keel boat to the beach. The exploding fiberglass is pretty interesting and scary - had not thought or heard of that..

My vote for the most dangerous to least dangerous lightning related places to be involving Hobie sailing (I could be wrong)

Most dangerous - boat on the beach with mast upright and you are standing very close to the mast on wet soil (for example, de-rigging the sail).

Next - boat is out on the water and you are in the water but near the boat. The currents in the water near a strike can be very high and even though they fall off with the square of distance from the strike, the boat and mast might have increased the chance that the strike was very close.

Less dangerous - On the boat - on the tramp - as far away from the lowest impedance path for the lighting to take - which is probably the mast to the frame then through to the water through the four places where the frame extends down into the hulls.

Least dangerous - in your car

This is the best I can come up with due to limited time. Scroll down to where they have gone ashore for a shower, and the electrical storm comes through. They did what keelboats are supposed to do.

http://www.geocities.com/alberg22/august2001.html

(It is also a good description of sailing on the Ottawa River. Our Club (the Kanata Sailing Club) is three miles east of Pinney's Point. One mile SE of us, on the Quebec shore, is the Aylmer Marina, then two miles east of us is Lac Deschenes SC, and four miles east of us is Nepean SC. Across the bay from NSC is the writer's home, the Brittania SC.)

_________________
2015 H16, with spin,
SOLD 1989 Hobie SX18 Sail # 1947 "In Theory..."
'Only two things are infinite, the universe, and human stupidity. But I'm not sure about the former.'

I am no expert on lighning but here is what I do know. Airplanes get hit by lightning often. From what I remember the thing there is to make sure that all parts are electrically bonded so that the ligtning has a path in AND out of the structure. I assume then the hope is that the path has the current carrying capacity to handle the bolt. I think on large boats the situation is the same, the mast and shrouds are bonded to the keel such that the electricity has a path. This serves an other more impartant function and that is to blead off any build up of static before it becomes too large. If your mast is electrically isolated it can become charged (like the static you build up rubbing your sock feet on the carpet) and thus making it more likely to be hit then if it were grounded. Lighning rods on houses and buildings work on the same principle (they are not there to carry the bold so umch as to make the area less attractive, that is why they are very pointed so that the static can blead off easier). Again back to airplanes, they have static whicks that do the same thing.

In short though I agree with the comment that the best thing is to not find yourself in the situation.

You can get shocked on the shrouds of an "insulated" mast because of the very high vertical electrical fields which can be present during a T storm. The bit of physics is that a conductor placed in an electrical field will take on the voltage at its mid point. The mast is one conductor and your body is the other and the mast mid point might be many feet above your body mid point so the mast takes on a different potential than your body. If you touch the shroud, you get shocked. So its really a different mechanism than "rubbing the cat".

I talked to one person who has known of 4 cases of lightning hitting sailboats in the Denver Colorado area. All the boats were in slips with no one on board and I dont know if the masts were grounded or not. One boat had a fire breack out and burned up. Another had a large portion of the glass of the hull damaged.