The Big Red Ball Does It Again

[Guest]

From the Log of Teacher's Pet III: July 31,2002-- 17:45 hours EDT. Well that was the lull before the first front. There were very large white thunderheads, then the sky on my stbd side started turning dark off in the distance. I slowed the boat down, pulled down the jib and rail fastened it between the hard upper rail and the cable at the second level. Then I put the gaskets in place on the main and lowered it and fastened it down to the boom and put the boom crutch in place and tightened down the main sheet. I started the 10 hp single cyl. Sabb and just started to turn the boat to weather when I was hit with the first gust. I estimate it
to be between 27-35 knots. The engine was not powerful enough to get me bow into it so I let the tiller go and went forward and dropped the Danforth Deepset.
the depth at this location in Florida Bay was 11'6". I let the 5/16" hi test chain out from the pressure of the wind and waves on the boat. When I got to the 100' marking I fastened the Big Red Ball to the chain and let out the last 10' of chain and then 50' of 5/8" black double braided nylon. when it was all set the ball bobbed up and down and took most of the strain of the shock load of the waves. The bow bobbed up and down but not as much as you would expect. About then the wind kicked up another notch; I got out my gauge and recorded gusts to 45 knots and a steady 32 to 35. Then the lightening and the rain started and it was hairy as the thunder would blast off and immediately the lightning would flash all around me. I quickly got my lightning gear over board and Prayed that I would Not get hit by the Lightning. The thunder was like Bowling balls hitting the pins and
as I was writing this in the log book under the pilot house I did not need to turn on lights over the nav. station. The Cell lasted between 45-60 minutes and moved off to port. About 2 hours later I pulled up the anchor and started on my way again!
Gene

Keep on Learning!!

 

[alan_d]

Lightning gear

"I quickly got my lightning gear over board...." What's that?

Alan

 

[vyv_cox]

Re: Lightning gear

Historically, this has been the signal for lengthy threads on various opinions on lightning. I use the word "opinion" advisedly - nobody knows for certain.

The lightning gear referred to means some means of directing a strike on the mast into the water. This is often lengths of chain attached to the shrouds, backstay and forestay, to be dangled overboard into the water. Why anybody should think that a lightning strike several kilometres long will be affected in the slightest by a couple of metres of chain is completely beyond me.

One of the few facts relating to this subject is that very few of the millions of boats in the world is struck by lightning and even fewer deaths and injuries result from them. Having been in a few thunderstorms at sea myself I can understand the desire to do something. I strongly believe that all such precautions are illusory - if your number is on it, there is nothing you can do!

 

[gunnarsilins]

You´re maybe right...

...that some wires och chains hanging in water probably would not make any difference if you have a direct hit by a powerful lightning strike in your masthead.

But there several experiences and reports tells of how boats can be hit and affected by small "side-strikes" and even the general static in the air. These small strikes can be powerful enough to kill all you electronic equipment and even destroy electrical wiring.
I these cases some hefty wires or chains attached to the shrouds and thus grounding the whole rig into water might help.
At least, I cannot see any reason why not to try. You have everything to win, nothing to lose!

 

[ccscott49]

Re: Lightning gear

I totally agree! All the "lightning conductors" in the world will not save you or more to the point your electronics, you will probaly be safe after having your boat hit by lightning, but your electronics will be fried! no matter what you do. This was the subject of millions of dollars/pounds/rubles worth of research to protect gear from an electro magnetic wave after an atomic strike, they still have not totally protected everything! So forget it, prayer has as much use as a length of chain!! IMHO of course, I'm already ducking, where's my old NI flak jacket??

 

[vyv_cox]

Re: Lightning gear

I can give some facts about the opposite case - making lightning hit something. Some of our Far East refineries had considerable difficulties over lightning strikes. Instrumentation failure knocked out production units, in some cases bringing down the whole refinery. Restarting a refinery is far from a matter of turning a few switches, it can take two days to get it going and a week to stabilise, hence considerable cost implications.

After some investigative work, these sites have installed four high towers at strategic points, each surmounted by a large metal sphere. It is evident in storms that these spheres are taking the strikes and the number of plant shutdowns has dropped dramatically. This seems to support the opposing situation as applied to yachts, in which a brush-like device at the masthead is claimed to reduce the likelihood of strikes.

My philosophy, probably no more valuable than any of the others, is that since I have a deck-stepped mast with no metal support, and therefore no direct contact with the sea, then I have a certain amount of natural insulation. Lightning therefore has no more tendency to strike my mast than it does the surface of the sea. The trouble with this, as I said earlier, is that sparks a couple of miles long don't follow the usual rules.

 

[ccscott49]

Re: Lightning gear

I've seen lightning atracters before, in west Africa, the tropics are quite famous for the electrical storms! In refineries aswell. My mast is the same, but even keel stepped masts arent in contact with the sea are they? unless wired to a keel bolt, which I've heard of, but seems silly! As you say, the voltages involved, will jump any gap anyway! So I tend to not worry about it, I've got a lot more to concern me in a storm anyway, thankyou! As for irradiated voltages, well if they are powerful enough to radiate, then the above rules apply!!

 

[sailbadthesinner]

Re: You´re maybe right...

mmm
but you would not catch me dancing on de3ck fixing lengths of chain to the shrouds in a storm.
In my brief experience of lightning protection for buildings any system needs to be well earthed and fairly substantial with minimal resistance or the strike will not follow the 'prescribed' route.

...It was like that when i found it!

 

[SimonD]

Re: You´re maybe right...

This may be complete nonsense, but I heard somewhere that the purpose of so called "lightning conductors" was not to conduct lighting but to ensure that the tall object was at the same electrical potential as the ground. This is intended to reduce the attraction of lightning to said tall object.

This seems to make sense if only because most lightning conductors (especially bits of chain hanging in the water) don't stand much chance of conducting hundreds or thousands of amps.

 

[Guest]

Re: Lightning gear

I have 8' of heavy duty cable that was used for welding; one for each shroud. The
end is fastened to a 3" copper pipe of 12" in length. Due to the amount of lightening in the Florida area, I leave it attached and lay it along the toe rail. There is a Samson post on either side forward which hold it on the deck out of the way. It is a very simple matter to drop it overboard. I do not claim it works any better than my Prayers!!

Keep on Learning!!

 

[Robin2]

Re: Lightning gear

This is firmly based on your interpretation of opinion ......

I favour those fuzzy wire things you can put at the top of the mast that are supposed to diffuse the voltage. (I have not got one, of course)

Remember that lightning goes up to the sky

 

[poter]

Re: You´re maybe right...

We had a lightining strike on a 32 foot Van de stadt in Dubai, which is also famous for its elec. storms, some years ago and it is not an experience I would wish to repeat. The strike hit us about 3 miles offshore and fried all the electronics, we did have a lightining protector which was connected to the shrouds via a cable then into the water with a large piece of expanded metal and a ball that they use on the overhead power cables ( a collector I think they call it) I am fairly sure that the protector saved us, even if the gizmoos got fried. We were in the cabin at the time so again I think that saved us from personal harm, is'nt that the same as the faraday cage principle???

Allah got some thanks that day..


poter.

 

[vyv_cox]

Re: You´re maybe right...

Was this a steel boat? I've seen film of cars driving around in enormous electrical discharge fields and been told that this was the Faraday cage principle, but I was not sure whether any insulating properties of the tyres were contributing. Aircraft are often struck by lightning (see http://lightning.pwr.eng.osaka-u.ac.jp/lrg/temp/plane.html for a superb example) without being damaged, but evidently they are isolated electrically from the ground. I have read that a steel boat is a very safe place to be in electric storms, but not clear if Faraday cage applies if the vessel is earthed?

 

[NigeCh]

Ground eddies

Lightning will always take the shortest path. Both clouds and the ground have potential eddies. IMO, if a boat is earthed from the mast into the sea, the masthead will have the same eddy potential as the sea and so shorten the distance. IMO, if a boat is grounded then it will be more likely to attract/generate a lightning strike than an ungrounded boat. (Reasearched by self and others, Fort Bragg 1978-82, ATA DART Ranges)

 

[vyv_cox]

Re: Ground eddies

Well, we seem to be in agreement over earthing!

I can see in my mind's eye the situation we were in two years ago between Dieppe and Boulogne. The air was clear around us, cloud base about 3000 ft, I guess. A line of black cloud chased us north, releasing enormous forked lightning strikes between clouds and sea. These struck all around us but probably never closer than 1 km. We suffered two waves of this with about an hour between them. It was brought home to me very strongly then that very little that I could do would have the slightest effect on this awesome power.

My only problem with our opinion is that lightning clearly does not always take the shortest path. Some of the strikes we saw on that day began on our starboard side and struck to port, and vice versa. Sometimes the angle of the strike was something like 45 degrees to the horizon, clearly not the shortest path. I think there can be a tendency for lightning to strike down the path of rain drops, but this would rarely get to such high angles, and on the day there was hardly a breath of wind anyway, so rain was falling almost vertically.

 

[peterk]

Re: lightning rod

way-all - as mah Suthahn friends would say:

I installed a lightning rod mainly
so the whole damn ornithology wouldn't sit on my
tri-color light. - actually it wasn't their sitting that bothered me so ...
Worst offenders were in ascending order:
3) seagulls
2) frigate birds
number 1) and still champeen, tah-taah: Osprey - they will also drop pieces of
their dinner, in the form of
organic vile-smelling glue on deck.

Anyway: I never did get struck by lightning.....

the rod supposedly creates a cone of protection.
I ran a battery cable from the bottom of the alum. mast
to the nearest keel bolt.

Once
while sailing (between the Galapagos and Cocos Island)
through under a huge black squall line
One single lightnig bolt flashed out of it
and struck the sea with an enormous crash, less than three
'Tehani' lengths away.
I was on deck at the time
There was a pressure wave, that almost
knocked me flat
and I humbly crapped in my shorts...

I was told later that a close lighning strike can also
do your electronics in.

Since I didn't have any
I can't corraborate.

...peter, www.juprowa.com/kittel