Lightning protection for you boat

[Mozzie]

Originally Posted by BigBeakie

B. Lightning will "seek" the surface of the ocean, not the bottom. Therefore putting grounding plates below the surface is somewhat counterproductive/suboptimal.

I don't understand the dynamics here very well, but charges tend reach equilibrium by moving to the surfaces of conductors - the ocean being a conductor. But in the short term, it may be that current flows perfectly well through the ocean to get to the surface.

I'd imagine steel yachts make good Faraday cages. What happens when they get struck?

[BigBeakie]

Mossie,

Do you mean the charge , "in the short term", would move from the keel or external ground plate through the seawater to equalise at the surface? I don't think so.

We are talking micro or nanoseconds for this process. If it can't happen in that incredibly short timeframe, then Mr. Bolt looks for another path. He is a very impatient guy. And that alternate path is still to the surface water even if it jumps through air to get there. Hence the danger of sideflash.

Steel ,and especially alloy, boats are essentially acting as Faraday cages. Lightning hits mast, field potential equalises to water surface at hull-water interface (via metal deck in contact with mast) virtually instantaneously, and so there is little risk of sideflash inside the boat.


Sent from my iPad using Cruisers Sailing Forum

[GTom]

AND there is nothing to burn on a metal hull. Metal boats are the safest bet against lightning damage - although I am not so sure about steel painted in multiple layers.

[GordMay]

Here’s an actual quotation & contract for supply & installation (including warranty & guaranty etc) of (7) DDCE-100HALO Lightning Suppressors, between EMP Solutions, Inc. and Santa Rosa County Fl.

☞ https://www.santarosa.fl.gov/agendas...kup-3358-1.pdf

[GTom]

Originally Posted by GordMay

Here’s an actual quotation & contract for supply & installation (including warranty & guaranty etc) of (7) DDCE-100HALO Lightning Suppressors, between EMP Solutions, Inc. and Santa Rosa County Fl.

☞ https://www.santarosa.fl.gov/agendas...kup-3358-1.pdf

That's approximately 15k$/unit+taxes+shipping+installation, almost as expensive as the boat I am planning to buy, leave me out... I rather cover the entire boat with 1000ft2 of copper mesh and be the clown of the marina.

[mikedefieslife]

Originally Posted by rosatte

Good luck

So what guage cable do I need from my mast to a zinc anode to prevent damage from that

[TreblePlink]

Perhaps if one can achieve the < 10 ohm "ground" connection, all forms of mast top electrodes would work pretty well ...

Actually measuring this would require another nearby "ground" connection that has significantly lower resistance - a very large submerged plate or a metallic boat.

[Mozzie]

Originally Posted by BigBeakie

Mossie,

Do you mean the charge , "in the short term", would move from the keel or external ground plate through the seawater to equalise at the surface? I don't think so.

We are talking micro or nanoseconds for this process. If it can't happen in that incredibly short timeframe, then Mr. Bolt looks for another path. He is a very impatient guy. And that alternate path is still to the surface water even if it jumps through air to get there. Hence the danger of sideflash.

I mean over nanoseconds. But I guess charge probably doesn't move that quickly through sea water. Charge moves in sea water through the movement of the sodium and chlorine ions. They would move at perhaps mm per second. Maybe the electrons from the submerged hull plate would enter the water neutralising the positive sodium ions causing a localised surplus of negative charged chlorine ions and hence a buildup of charge that would inhibit the further flow of charge. Although I think lightning usually operates the the other direction - the electrons go from earth so perhaps chlorine ions give up their electrons to the plate causing a surplus of positive sodium ions.

But I wonder what makes charge dissipate better across the surface of water...

Just thinking aloud...

[Mozzie]

Originally Posted by GTom

AND there is nothing to burn on a metal hull. Metal boats are the safest bet against lightning damage - although I am not so sure about steel painted in multiple layers.

I'd imagine the current would just blast through the paint as paint is a very small barrier in this situation. In reality the amount of paint lost could be square centimeters.

[thomm225]

Looks like the lightning protection systems we have available today still increase the chances that your boat could be hit.

Protecting your boat from lightning.

Most of the studies and articles we've read (and we list many links to them below) agree that a well designed and properly installed lightning protection system on a boat can help minimize the damage once your boat does get hit. Unfortunately, many sources indicate that that same system increases the likelihood that your boat will be hit.

[rwidman]

Originally Posted by btrayfors

Might make you feel better, but totally ineffective.

Some years ago while at my favorite bar adjacent to Bahia Mar in Ft. Lauderdale I watched a direct hit on a small powerboat which was slipped in between two large sailboats. The sailboats were not damaged, but the powerboat was destroyed.

....which led me to the conviction that:

Nothing, absolutely nothing is going to prevent a strike. The voltages are incredibly high and will ensure that lightning not only takes the shortest path to ground, but in addition TAKES ALL PATHS TO GROUND.

Chocolate on the cabin sole sounds like as good a solution as I've heard, particularly when accompanied by a full measure of rum :-)

Bill

You missed the "" at the end of my post, didn't you?

[TreblePlink]

I wonder what the charge is for the DDCE "annual inspection" ?

I suspect these devices may be no better than many other lightning protection systems, except that the very high prices subsidize their actuarial costs of paying for the warranty.

They are too new to see how well they stand behind their claimed guarantee. They may play games like "pro rata" value when faced with a claim, or have excessively stringent standards of proving damage...

[GTom]

Originally Posted by TreblePlink

Perhaps if one can achieve the < 10 ohm "ground" connection, all forms of mast top electrodes would work pretty well ...

That's nothing extreme: Round Wire Resistance Calculator

[Hobschel]

Originally Posted by thomm225

Looks like the lightning protection systems we have available today still increase the chances that your boat could be hit.

Protecting your boat from lightning.

Most of the studies and articles we've read (and we list many links to them below) agree that a well designed and properly installed lightning protection system on a boat can help minimize the damage once your boat does get hit. Unfortunately, many sources indicate that that same system increases the likelihood that your boat will be hit.

i was thinking exactly the same, so a carbon mast and spectra rigging would lower the chance of being hit... but if it would be worse...

[transmitterdan]

Originally Posted by TreblePlink

I wonder what the charge is for the DDCE "annual inspection" ?

The PDF says $300.00 per year. No mention if that includes travel costs and tower climbing costs. Also, it seems hard to understand exactly what the inspection entails. Measuring 10 ohms resistance between what and what? A ground resistance of 10 ohms is actually pretty high in my experience so it's probably not that.