Boating in thunder & Lightning!!!

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Rock

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Can any body advise me of just how dangerous this is if the boat was struck by lightening, does it have the same effect as on land?
On Saturday we were fishing about 15miles off the sussex coast & there was some lightning in the distance, this soon 'engulfed' us and there were some horrendously loud cracks with at the same time as the flashes. All of our electronics (GPS, fishfinder, VHF) etc went off. when we switched them back on, they all functioned normally.
Were we struck (no signs of any damage) or was it the static in the air causing them to go off???
Whichever it was, my ears have only just stopped ringing!!!
 
Not especially dangerous - well your still alive aren't you.

No not struck, what happens when there is a lightning strike somewher is that a very high voltage electrical field is generated which then is dissipated in a very short duration flash of lightning.

Any conductor within this field when it collapses will have a voltage generated in it and its this that has caused your electronics to go tilt.

Fortunately not terminally - so thats OK

In a storm thats close to you its best to turn off the kit if you can and to disconnect the VHF aerial, which usually is the longest and most vulnerable bit of wire.
 
No doubt there will be a technical explanation why all your gear went of and still worked but I was advised to get the sails off and hang a bit of chain attached to the foot off the mast over the side. Never had to do this but I have seen the dramatic increase in wind and sudden change of direction that can accompany a thunder storm.
I will interested in the forumites views on best course of action
Regards
GrahamC
 
Richard Woods wrote a good article about lightning strikes following a strike on his Eclipse in the States which did a lot of damage. The article appreared in PBO.
 
Not much you can do, except read some of the acounts on these forums concerning bonding and hanging chains over side - and then reach your own conclusion.

I have seen 3 boats as they have been struck by lightening, none sank, I have see ligtening fizz as it hits the sea, thankfully my boat has escaped - so far - in all cases I have seen there were no crew injuries except some bruising when a helmsman was thrown from the stainless wheel and he hit the aft cabin.

In every case some electronic equipment was damaged in one everything was scrap, batteries, wires, starter motor, alternator, switch panel, etc. on others only one or two pieces of electronics were damaged.
 
As Bergman says, induced current must have caused overloading of your instruments and turned them off, you have been lucky if the bolt had been nearer consequences might have been worse

I sailed a lot -still do sometimes- in the adriatic, a warm sea which is one of the highest producers of thunderstorms, especially at night, exactly when one usually crosses the sea east ot west, and every time thunderstorms formed it was a frantic search for new religions

we have been struck just once, by what I reckon was a small lightning, it just blew the vhf antenna (which came down from the mast top in flames) +vhf set, the compass kept turning for some time; the mast step was grounded to a keel bolt, it has maybe had some beneficial effect

some other boats there have experienced seacocks popped out, one has dismasted, another one with the mast stepped on deck has had a wide combusted area around the mast base

if you would like to try and protect your boat, the ABYC and ISO have produced two standards with some maybe useful comments, although they basically advise to ground the mast step to the keel

I personally would not bother with the chain: the mast has such a higher conductivity than steel (shrouds) that anyway most of the current will try to go through there, if it is deck stepped then it is very likely that the current will ionise air and jump to the keel anyway, striking anything in between; also, handling a heap of metal like chain in an electric athmosphere, means that should a bolt strike, the chain and yourself would provide an easier path to ground... that is one of reasons why it is often recommended to stay away as much as possible from metal parts of the boat

anyway, don't know how much exact science there is behind, a book of prayers can always come handy /forums/images/graemlins/crazy.gif
 
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Whichever it was, my ears have only just stopped ringing!!!

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The above certainly brings back memories!

My house was struck by lightning 20+ years ago. My one piece of advice would be that no matter how loud the bang, no matter how much it makes you jump.......... that one missed!!!

I still, to this day, have no recollection of the thunderclap accompanying the lightning bolt.......... and I'm told the sound was incredible............ but my ears were ringing for days.

We lost half the roof, most of the ceilings, obliterated the wiring (where the plug sockets had been there were just large holes in the walls).

Upside is that despite being blown out of the chair I was sat in (first recollection is picking myself up off the floor) I was totally unharmed as were my two sons who were asleep upstairs (unbelievable when you consider the joist underneath my youngest son's bedroom floor was split in half by the blast).

Overall considering the exposed position of a yacht during a thunderstorm it would appear that the odds are happily stacked towards our survival but not necessarily the electronics.

Hope this brightens your day
Paul. /forums/images/graemlins/smile.gif
 
Crikey!

We were struck at home about 6 weeks ago.... nothing as serious as that... but we did lose an awful lot of our electrical and electronic goods....

I can equate with some of it though.... we didn't hear the strike/thunder either.... perhaps just 'felt it' is the best description....
 
Boat ovens also make perfectly good Faraday cages.(provided you're not using them at the time, of course) If you get the chance put all the small stuff you can in there; vhf, gps handheld compass etc. Should protect them. People always laugh when I say this but more knowledgeable people than me have agreed.
 
The things to do if you are caught out in a thunder storm is to disconnect all antenna and other power connections to electronics. I am not convinced about the need to put them inn the oven. Make sure no one touches any metal especially stay wires.
The earthing of the mast seems to be important. Heavy wire to the keel or a ground plate at least 2 square feet. You especially want to divert the current from flowing in the stay wires which being resistive will melt quickly from high current.

A lightning strike is not going to move sideways to find your boat unless it is a shorter path to the sea so a potential strike needs to be within a radius of your mast height for it to be attracted. When you consider the number of yachts on moorings through all sorts of storms they are seldom struck by lightning so don't worry so much. Just enjoy the display if you can.....olewill
 
[ QUOTE ]
Richard Woods wrote a good article about lightning strikes following a strike on his Eclipse in the States which did a lot of damage. The article appreared in PBO.

[/ QUOTE ]


And Here it is.

PBO have posted it as an example of their archive.

If you right click on the pages and save them as images it's possible to print these artices off for free...
 
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