Lightning strike/Surge protector

Hello, just new to this forum. I was wondering if anyone had some information about surge protectors for lightning strikes. Do they work? Can anyone recommend a brand?

On sailboats at least, there is no consensus and very little actual data concerning lighting protection. It is a highly variable, chaotic event. Boat US, a very large USA insurer, says that there is no difference in strike frequency between those boats with static dissipators and those without. The normal prescription for protection is to run a heavy cable from the mast to a grounding plate or the metal keel, keeping the bend radii large. It is apparently not the first strike that usually does most of the damage, but the return surge which is lower in current, but much longer in duration.

A university in Florida tried to do some testing and theory and came up with an more elaborate grounding scheme involving a low impedance conductor around the shear line of the hull, connected periodically to a keel grounding system. No one knows how well it works. I know boats that have taken direct hits that have had little damage, to more typically most of the electronics ruined, to sunk when the thru hulls vaporized.

If lighting hits the power grid near you, then a surge protector might help save some equipment connected to it. These work by trying to sink higher than normal voltages to ground. They may have some value, depending on how near the strike is. The best protection from that on a boat is to leave it unplugged from the grid.

The closest I've come to a strike was one that hit an 80' tall 60 year old oak tree about 100' from my front door. It sounded like a bomb had hit, the trunk of the tree exploded. We found chunks of bark 200' away.

Sorry for the late reply DDW, we are cruising around Bocas Dl Toro and now back in coverage! Yes I did fined your thread on line and some more that were similar!
We are alloy and our vessel is wired negative ground and we don't have bronze through holes, so may be in a better situation? We will just have to rely on good management. Cheers

Alan Culverwell said:

Hello, just new to this forum. I was wondering if anyone had some information about surge protectors for lightning strikes. Do they work? Can anyone recommend a brand?

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DDW has a pretty good summary. I will add just a little, since I do design work for lightning protection, (but not boats).

As with every other atmospheric event, lightning comes in sizes. You will not protect against the largest strikes. But, there is a lot you can do to limit and even eliminate damage with many strikes and near misses.
"surge protection" is a 2nd or even 3rd level of protection; not primary. First, you must divert 99% of the energy to a safe place. In a plastic boat, that is challenging, but good progress can still be made with bonding and smart discharge points.
There was done a very interesting mitigation to a N47, I think it was, that included hull mounted discharges just above the water line.

My last boat, which had a fishing tower made of aluminum, I did do quite a bit of bonding, and some surge protection, even on the 12V systems. It never took a direct hit, but some of my personal learnings were as a result of a direct hit to my house.

I have heard on my VHF, large boats calling for help due to a hit; I do try to do some stuff to prevent catastrophic damage to all comm, nav, hull, and propulsion.

Thanks Diver Dave. I take on board what you are saying. It seems that you need to do your due diligence when necessary. And as both of you have threaded a good grounding is the right place to start. Being Alloy I don't think that is it necessary that we need to go down this road??? Cheers

Metal boats do make this a lot easier.
One item to keep in mind is this idea of "spare electronics". You really would want to consider keeping "spares" NOT plugged in to any external device, such as transducers, power, antenna, etc. That way, the "spare" will not be impacted by an unfortunate atmospheric event.

Lightning strike/surge protector

Lightning is one thing but what about protection from surges in shore power? For example; last year I was at the Varadero marina in Cuba and despite their assurances when they plugged me into their shore power there was an ungodly explosion, pops, smoke and they fried half of my electronics. Ended up costing me $5,000. They disclaimed any responsibility. I will never go back to that marina. Sure wish I had some protection at that time.

Mike Lowthian said:

Lightning is one thing but what about protection from surges in shore power? For example; last year I was at the Varadero marina in Cuba and despite their assurances when they plugged me into their shore power there was an ungodly explosion, pops, smoke and they fried half of my electronics. Ended up costing me $5,000. They disclaimed any responsibility. I will never go back to that marina. Sure wish I had some protection at that time.

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If I understand correctly, that issue happened the moment the shore power was plugged in or energized? Probably not a surge, but a Hot to ground swap or the wrong nominal line voltage altogether.

Thanks Mike, we stayed at Santiago De Cuba and the lack of information about there shore power made it easy to not connect!!!

"we stayed at Santiago De Cuba and the lack of information about there shore power made it easy to not connect!!!"


An $8.00 VOM from Harbor Freight will tell you all you need to know , before plugging in.