Lightning protection
- Thread starter geem
- Start date
Roberto
Well-known member
Yes sure, sorry bad attempt at some sort of humour. Instead of two independent events (where one multiplies the two probabilities), it would be nice if lightning strike had some sort of memory and decrease the probability of striking the same object a second time. All delirious fantasy of course, once stricken the probability of being struck a second time is the same
Sea Change
Well-known member
Interesting. The ex-NASA guy I mentioned earlier suggested that you want a build up of ions...I cannot answer the OP, but the LightningMaster, Home is worth considering. They have been in business for many years now. For a moderate cost, this passive device could save you grief. We have one and survived a strike that was extremely close. The theory is that it prevents a build up of ions at the mast head. I am sure that it does that but not sure that it will always prevent a strike. After our experience, I always recommend it.
I could be completely misunderstanding how this works though.
Bouba
Well-known member
Neeves
Well-known member
It's also been observed to have reliably kept elephants away.
We did not have one but we still saw no elephants at sea.
geem
Well-known member
We were in West Palm beach, Florida a few years back. Its lightning central. The storm thst came through ranked on a different level to anything we had experienced in the UK. There were strikes very close by. We had the instruments on and I watched the depth guage and wind speed behave erratically, just before a strike that was super close. That strike didn't give us a direct hit but it destroyed the mast head light and an LED deck light as they both had electronics in them. I am guessing we were so close to the bolt of lightning that we suffered an electromagnetic pulse above the boat. At the time, we had our masts earthed to the ground plate, so maybe another save?I cannot answer the OP, but the LightningMaster, Home is worth considering. They have been in business for many years now. For a moderate cost, this passive device could save you grief. We have one and survived a strike that was extremely close. The theory is that it prevents a build up of ions at the mast head. I am sure that it does that but not sure that it will always prevent a strike. After our experience, I always recommend it.
Bouba
Well-known member
This is like having a conversation with old people....’I’ve got terrible flu....luckily I just had my flu-jab or it would be much worse ‘
Roberto
Well-known member
Or just consider how diverging are the number of expert/very expert advices
capnsensible
Well-known member
Well at least you are reading about people who have actually been at sea in electrical storms. It's certainly not my fave thing when you are the only tree in the forest....
billskip
Well-known member
One things for sure...if you hear the bang you are still alive....
I lived in a wood built bungalow on concrete stilts, was struck by lightning, lightning dancing around the room seemed like an age, but was probably no more than a couple of seconds if that,deafening the noise.
I was in a park and saw a tree get hit, the noise again was unbelievable.
A neighbours house got hit blow a hole clean through his roof and melted hit loft tv antenna.
When I was in Venezuela there is an area there that's the most common, Lake Maracaibo, not for the faint hearted....
Roberto
Well-known member
+1, absolutely. Being in the middle of the sea when it's flashing all around and the single metal pole sticking out of the sea surface for miles and miles around is yours... ok cones of protection, etc, but really not sure (the experts/very expert opinions are really not univocal either) any ground connection or not makes any significant difference.
I put gps+epirb+some electronics in a copper foiled box then in the oven, who knows, it might help. A few years ago there were reports of a number of experiments made at the Siemens lightning simulation center, now google has probably made them disappear into 2nd 3rd order pages.
franksingleton
Well-known member
We bought Anhinga in the mid-90s. For about 10 years, whenever we were near thunderstorms or, even when there was just a stronger than normal, electric field, our ST60 wind indicator would go berserk. It would start to oscillate stronger and stronger before spinning madly at great speeds. All we could do was to turn off the electrics and wait until all the static had gone.
In 2004, we had the lightningmaster fitted. Then, in 2004, September 8, we were on passage around Sicily, Marsala to Sciacca. The forecast was isolated thunderstorms. It was very hazy. We wondered why fishing boats were going at high speed towards port. Then we saw a massive thunder cloud very close. There was a lightning strike so close that we could hear the air crackling as it was ionised. The ST60 gave one little flick and that was all.
Clearly, I do not know whether or not the LM prevented us from being struck. I do know that it prevented the build up of static. As fas as I understand it, the dissipation of static is what prevents or, maybe, reduces the likelihood of a strike. As the risk seemed so low, all our vulnerable gear was out and vulnerable. We could have lost laptop, iPad, cell phone etc. and we were the only tree. I would not be without my Lightningmaster. Clearly, it gives some protection but, probably not total.
PS. The mast is earthed to the engine block/sacrificial anode.
In 2004, we had the lightningmaster fitted. Then, in 2004, September 8, we were on passage around Sicily, Marsala to Sciacca. The forecast was isolated thunderstorms. It was very hazy. We wondered why fishing boats were going at high speed towards port. Then we saw a massive thunder cloud very close. There was a lightning strike so close that we could hear the air crackling as it was ionised. The ST60 gave one little flick and that was all.
Clearly, I do not know whether or not the LM prevented us from being struck. I do know that it prevented the build up of static. As fas as I understand it, the dissipation of static is what prevents or, maybe, reduces the likelihood of a strike. As the risk seemed so low, all our vulnerable gear was out and vulnerable. We could have lost laptop, iPad, cell phone etc. and we were the only tree. I would not be without my Lightningmaster. Clearly, it gives some protection but, probably not total.
PS. The mast is earthed to the engine block/sacrificial anode.
Last edited:
noelex
Well-known member
Below is a simple, but accurate summary of lightning protection (note lightning protection on yachts is unfortunately mainly about minimising the damage if struck rather than significantly reducing the chance of a strike).
Sailing in lightning: how to keep your yacht safe - Yachting Monthly
Sailing in lightning: how to keep your yacht safe - Yachting Monthly
William_H
Well-known member
Near the end of Nigel Calder's story he claims that spiky or brush type disipators on top of mast are of doubtful value. I disagree. Aircraft for many years have had similar dissipators attached to the trailing edge of wings and tail to help dissipate static build up. Helping reduce radio interference from large build ups. They work by concentrating static build up to fine points where they are more liable to discharge at a lower voltage.
Now a lightning strike on an object starts with the up stream of ionisation. The risk of this happening can be reduced by dissipating static build up at a lower voltage or energy level. NB in terms of this initial riser electrical resistance to sea does not matter much so wet GRP etc can conduct well enough.
So pointy or brush type discharge devices may reduce risk of lightning strike.
The concept of high current capability conductor (ali) mast to sea is one of the best protections. The conductor will probably get very hot. Possibly even vaporise so fire might be a consideration in mounting the conductor.
Next problem is that this huge current will act like a transformer inducing voltage into any conductor nearby. Hence the idea of putting radios etc in the oven which makes a shield. This has merit. Certainly disconnecting plugs and cables may reduce risk of damage. People should avoid contact with any metal if possible.
ol'will
franksingleton
Well-known member
A lot of the discussion of the wire brush is theoretical. I am one of the few who have actually seen that it does do what the manufacturers claim. It clearly, on our boat, prevented the build up of static that we know used to occur. To what extent that reduces the risk of being hit is unknown. On the basis of one near miss plus the certainty of avoiding static build up, I am more than happy to recommend the wire brush approach. Does anyone have other suggestions based on personal experience?
geem
Well-known member
I like the idea of the wire brush. As I said in post #26, I saw the static effect on my instruments going crazy just before a very near strike. We didn't actually get hit but a wire brush may have saved my masthead light and deck lights. During the very violent lightning storm I mentioned in my first post, we left the instruments on but never saw the crazy instrument behaviour. This was a surprise considering the hundreds of strikes around us but also reassuring. If we had seen the crazy instrument behaviour, we would have got in the safest part of the boat rapidly, knowing the next likely event was a strike.
I think a wire brush at the top of the mast and a masts that are earthed to the sea may be as good a lightning prevention solution as it is possible to get. Dealing with a direct hit is a completely different installation and even done to the highest standard, isn't likely to protect all the electronics onboard so in my mind isn't worth the expense and disruption to install, unless my boat was based full time in Florida or the San Blas islands, Panama where strikes on boats are a very common thing
franksingleton
Well-known member
As I see it, it is cheap. It takes no power. It does prevent a build up of static . It might well prevent a strike. To me, that seems preferable to trying to get rid of massive amounts of charge. It might work, the alternative might not.
