Lightning and beach cats

The background for this question is that we were sailing an F18 in a 20 NM distance race yesterday. The wind was a nice 10 to 15 knots with seas up to 1 meter, so nothing extreme, except that the air felt 'unstable'. About 1 NM from our final mark rounding, the lighthouse (which was the rounding mark) 'disappeared' in a heavy squall, there was some lightning, and then some thunder in the direction of the lighthouse. It didn't seem terribly smart to continue, and since we were already in last place by quite a ways, we decided to 'stop racing', fall off and sail the quickest route back to the beach. On the way in, we got hit by a couple gusts up over 20 knots, but we made it back safely. It sucked bowing out on the last rounding of a fun race, but safety comes first.

Obviously one should avoid being out when there is thunder and lightning. But the question is how dangerous is it to be on a beach cat in a thunderstorm, and what should one do when 'caught out' in a storm? In hindsight one nice thing about the F18 is that its speed helps to run away from bad weather, but at the same time hanging on a trapeze seems like a really easy way to get zapped if lightning strikes.

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eric e

Super Anarchist
lightning paths seem somewhat complicated and rarely predictable

basically you want to avoid getting anywhere near lighting and do all possible to avoid being in the energy/plasma path that any strike may flow through

trapezing then would be a BAD idea

as the mast is the most likely strike point and the hulls the most likely earth/discharge path

you would think that the energy would simply flow down the mast, into the beam, through the beams seats into the hulls, then water and gone

BUT on my nacra the rotating mast sits on a plastic ball that won't want to conduct

so there will be an explosive bottleneck there and energy will also go down the stays and trapeze and me, if i happen to be on the wire

so maybe stay on the tramp, or rear of the hulls, or rear beam

but don't be near the mast, sidestays or trapeze wires...

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Pete Pollard

Super Anarchist
I leave the water when lightening threatens. Got stung once, like a spark plug on a lawnmower. That was enough.



Super Anarchist
Kent Island!
Lightning would be VERY bad on a typical beach cat.

Bring jumper cables and clamp on end on the mast and let the other end trail in the water. You might need a bracket or fitting added to clamp onto. No guarantee, but it would at least give the current an easy path to the water that doesn't involve you.



Super Anarchist
I would suggest the best plan of attack would be to have a grounding strap from the mast to the hulls if they will conduct well to the water. A carbon hull has a lot more resistance than something like aluminum or copper, but will still conduct electricity pretty well. If you really want to go crazy you could have a grounding mechanism to transfer electricity to the water like the jumper cable described above. A jumper cable might actually work very well if you stripped the copper wire to maximize surface area contact with the water and sufficient gauge thickness of wire. Plus it would be cheap and easy.

The second suggestion would be to use synthetic shrouds and synthetic trap lines. Keeping the flow of electrical current as far away from you as possible.

Finally I would remove any sharp corners or points from the top of the mast. It's hard to explain without going into more complex physical properties of electricity, but in layman's terms electrical charge intensifies around pointy stuff. When the electrons gather at a sharp point they are most likely to "jump off" into the air in an arc of lightning. To hopefully avoid a sufficiently intense charge to arc, rounding off pointy stuff can actually help avoid being "struck".

The fourth would be to sail next to a beach cat with an aluminum mast. It will conduct much better and probably be struck before a carbon one.



When there is lightning, then probably there is rain. When it's raining, then everything is wet. Lightning will find it's way from top to bottom along everything that's wet, metallic or synthetic.

A thick copper cable from the mast into the water might help, as well as staying away from the mast or anything else solid and/or conducting, and on a thick rubber cushion. And keep your head down.

Still, leaving the water is the better idea.