lightning protection

[rsmith]

So, what are those "dynaplates" (I think that's what they are called) on the underside of my boat and what exactly do they do? Do they have anything to do with lightening protection? I have one on each side of the hull. I think, not certain, they are under my genny room on each side of the hull.

SSB groundplane
But wait for REB's answer. It will be much more comprehensive.

 

[Boatsb]

On a more serious note:

Apparently the theory for lightning protection is that a decently grounded high lightning arrestor, placed well above other objects on a boat, will often disippate leader (charged particle) build up that usually precedes a lightning strike. Such rarely protects against an actual lightning strike.

What I did in the NY-CT region is to ground my radar arch via a #4 battery cable hanging over the side...and weighted down with a big zinc....from a ship. I attached it only when lightning approached via a wing nut on a stud at the base of the radar arch. (dockside I attached it to my bonding system via another wing nut/stud in my YF cockpit to supplement underwater zincs)

Atop the radar arch I placed a pointed lightning spike arrestor atop about two feet of stainless 1/2" rod...so I had to lower my antennas for further protection. Cost was under $100 or so and seemed a reasonable precaution.

No grounding system on a recreational boat is likely to protect everything once lightning strikes without horribly expensive modification. The cable should be heavy guage, #4 or bigger is the current recommendation I believe, have NO sharp turns, and be grounded separately from other hull grounds. That's why hanging a cable outside the boat makes so much sense...physical isolation, pretty much a straight line down, and a separate ground. Its downfall: no protection when underway.

If I were boating for extended periods in Florida, I'd likely have taken a few further steps.....such as setting the lightning arrestor much higher, maybe on a pole that could be lowered when not in use.

I still don't know what system non metallic mega yachts use for protection.

Stainless is a lousy conductor. probably didn't do anything since the aluminum and copper in the items around it would attract the lightning better.

Copper is the only way to go with lightning protection. Look at the systems they put on TV towers.

 

[jmencel]

... by the way, many sailboats simply hang a good sized piece of chain from the shrouds (wires that hold up the mast) and drop the chain into the water when lightning is in the area. Could be a way of temporarily grounding a radar arch or another "pointy" metal thing ? ...

 

[Canuck Dennis]

I was led to believe that the fore and aft stays on a sailing vessel were good protection for lighting strikes as the idea was to have a "tent like effect" where the strike would follow the stays down and then dissipate .

later I heard that idea failed when a strike blew out the bottom of a 48 ft sailing yacht so rigged.

It's like getting mugged....try not to be in that location !!!!

 

[REBrueckner]

"Stainless is a lousy conductor. probably didn't do anything since the aluminum and copper in the items around it would attract the lightning better.

Copper is the only way to go with lightning protection. Look at the systems they put on TV towers."

I'd also vote for copper...especially in FLA...

Now that you mention it: I have noticed Home Cheapo copper rod (don't know if it's solid or coated steel) for use in home grounding....the ones you drive into the ground.....one of those, maybe sharpened to a point could be an economical lightning arrestor "spike".....

The Lightning arrestor (spike) I bought at a Marine store was aluminum....But keep in mind you are primarily dissipating static electricity here....most any metal will help....and none will provide a guarantee of protect against an actual strike..

Dynaplate: I have no personal experience but test results I saw a number of years ago found they clogged with marine growth after a year or two and so were not very effective...

For Lightning protection, see the Kasten article I posted...

Also, as I have posted multiple times here before: When lightning strikes, it's not uncommon for it to blow up thru hull fittings...which are bonded....and sink boats.... That's from insurance industry reports I have seen....That's one reason for NOT bonding high quality silicon bronze thru hulls....

 

[REBrueckner]

"I was led to believe that the fore and aft stays on a sailing vessel were good protection for lighting strikes as the idea was to have a "tent like effect" where the strike would follow the stays down and then dissipate .

later I heard that idea failed when a strike blew out the bottom of a 48 ft sailing yacht so rigged."

If those stays are separately grounded and properly wired for lightning protection they might HELP protect someone on deck.....and equipment below. But there are absolutely no guarantees with lightning....

Nor have I seen evidence that such protection makes things worse....but I have not researched that kind of thing in some years....so I could be out of date.....if it did make things worse I would think insurance companies would not insure such boats in Florida like locations.....