Lightning protection...any thoughts?
- Thread starter robmdknapp
- Start date
BrianH
Well-Known Member
I sail in a particularly violent thunderstorm-prone area and frequently anchor in the NE Italian lagoons where my mast is the single highest point for many miles as I watch the blackness split by vivid lightning strikes approach. With a metal mast, a forestay connected to the bow fitting over which runs a chain leading down to a buried anchor I think I must be the ideal earth link. I've never been struck yet though (fingers crossed).
But my friend has. He was sleeping early one morning in the forecabin while hauled out in the marina - the metal cradle probably made a good earth. His electrics were blown and the anchor winch above his head was frazzled but he was unharmed. All around were boats with higher masts and 50m away was a 30m, metal latticed, radio tower with a lightning conductor that did not divert the strike.
The forces involved are so vast that a strike path is likely to be quite arbitrary and random, I suspect.
But my friend has. He was sleeping early one morning in the forecabin while hauled out in the marina - the metal cradle probably made a good earth. His electrics were blown and the anchor winch above his head was frazzled but he was unharmed. All around were boats with higher masts and 50m away was a 30m, metal latticed, radio tower with a lightning conductor that did not divert the strike.
The forces involved are so vast that a strike path is likely to be quite arbitrary and random, I suspect.
KellysEye
Well-Known Member
We have seen a number of boats hit by lightning and we were very lucky when lightning hit the water about 50 yards in front of the boat and we had Elmo's fire crackling in the rigging. It's so powerful it's very difficult to stop damage, the boats we saw that had been hit had all their electronics wiped out and one had scorch marks on a flag on the backstay. The only thing to do is unplug every instrument and hope for the best because the wiring to the instruments will probably fry.
Another incident we had was I was on night watch off the Venezuelan coast and the radar was showing lightning 25 NM in every direction. There was the loudest bang I've ever heard, the brightest flash and the smell of ozone, thankfully it was all cloud to cloud.
Another incident we had was I was on night watch off the Venezuelan coast and the radar was showing lightning 25 NM in every direction. There was the loudest bang I've ever heard, the brightest flash and the smell of ozone, thankfully it was all cloud to cloud.
[70521]
Well-Known Member
Is there any research on the number of pleasure craft hit by lighting each year? Is it a major problem?
robmdknapp
New Member
Have worked my way through the first of these...very informative...many thanks...
robmdknapp
New Member
Not sure if a major problem in UK waters, but certainly there are some regions of the planet where apparently over half of all sailing boats have been struck (according to a piece of research I read this morning)!
Given that we prepare well to mitigate/minimise the risk/consequences of other potential problems I am interested in what, if anything, I can do as part of my major refit to address this. So far, I am going down the path of:
Dissipator at masthead (£120)
vertical 25mm2 copper conductor from mast step to hull plate (£30)
bronze hull plate (£120) needs to be cleaned with a wire brush each year
horizontal copper conductors (16mm2) bonding major metal objects to reduce side strike (£20) plus TVS (transient voltage suppressors) at each electrical component (£20)
Advice/labour from a sparky - £60.
Just over £300+ all in - seems that this is recommended by anyone who thinks that lightning protection is worth doing something about. In the grand scheme of things it is one of the smallest of my refit costs...
spannerman
Well-Known Member
We had a Halberg Rassey 40 on the hard for winter and plugged into shorepower. We had a thunderstorm and actually saw the lightning strike the VHF antenna which is at the top of the mast, the damage was extensive, it blew the glassfibre VHF sheathing to smithereens and the LED tricolour blew out of its socket.
It travelled via the negative side of the boats system and took out virtually everything with a circuitboard, I replaced the Chartplotter, GPS, Autopilot and fluxgate, all instruments and repeaters, VHF radio, both battery chargers and DC/DC converter, CD/radio. The engine alternator and electronic control box, also had to rebuild the entire power distribution panel and replace every LED warning light on the panel and binnacle. Both shorepower circuit breaker cabinets, and shorepowersocket, Eberspecher control board, gas detector, smartcharge monitoring system, numerous halogen lights and various other bits like every 'T' connector in the NG 2000 network, and tank senders. Also all the wires in the deck stanchions from bow to stern were burnt through, the only thing that survived was the bow thruster.
Interestingly the cables in the NG network and those through the mast were fine they were all checked with an Ohm meter, including the VHF cable which lead the strike into the boat via the VHF radio through the negative side and out through the shorepower earth where it blew the socket on the power post to pieces on its way to earth, it then continued through the steel rebar in the quay and blew chunks of concrete out the surface at the end of every steel rod ! It took me 50 hrs to replace everything, and cost £80,000, because the boat was only a year old the insurance covered it,
It travelled via the negative side of the boats system and took out virtually everything with a circuitboard, I replaced the Chartplotter, GPS, Autopilot and fluxgate, all instruments and repeaters, VHF radio, both battery chargers and DC/DC converter, CD/radio. The engine alternator and electronic control box, also had to rebuild the entire power distribution panel and replace every LED warning light on the panel and binnacle. Both shorepower circuit breaker cabinets, and shorepowersocket, Eberspecher control board, gas detector, smartcharge monitoring system, numerous halogen lights and various other bits like every 'T' connector in the NG 2000 network, and tank senders. Also all the wires in the deck stanchions from bow to stern were burnt through, the only thing that survived was the bow thruster.
Interestingly the cables in the NG network and those through the mast were fine they were all checked with an Ohm meter, including the VHF cable which lead the strike into the boat via the VHF radio through the negative side and out through the shorepower earth where it blew the socket on the power post to pieces on its way to earth, it then continued through the steel rebar in the quay and blew chunks of concrete out the surface at the end of every steel rod ! It took me 50 hrs to replace everything, and cost £80,000, because the boat was only a year old the insurance covered it,
KellysEye
Well-Known Member
The San Bas islands off the Columbian coast are the lightning capital of the world. However for some reason it only hits some of the island so if you avoid those, you can see the damage to trees, anchoring there is fine. Also there is a lot of lightning along the Columbian coast after September so it's wise to avoid sailing then although we have known boats do it without problems.
robmdknapp
New Member
Thanks to all posters for your input - have learnt a lot in 2 days!
Not 100% sure lightning protection will make a huge amount of difference, but I know what the system should entail & I think I am planning to install.
Much obliged.
Not 100% sure lightning protection will make a huge amount of difference, but I know what the system should entail & I think I am planning to install.
Much obliged.