Hull grounding plate

[Oldwheels]

Not sure where to post my question but here goes.
My boat has a copper grounding plate in the hull. This is exposed to the sea. The mast and all things share this common ground. Right now my boat is on the hard getting painted and love. I noticed the grounding wires to the plate disconnected. This got me to thinking.
Now the plate and wiring I first assumed were for lightening. But then I was thinking this would possibly add to galvanic corrosion. Or may be it would help stop corrosion.
As a side note I go thru zincs in two months.
Should I hook these back up?
New boats do not have this plate and wiring
Now I am confused. Your thoughts and knowledge please!

[hpeer]

A normal ground plane would be on the inside. You have a ground plane for a SSB radio to help the antenna work.

Something outside the boat like you describe would more likely be for lightning protection. Where did the disconnected wires go? To the chain plates?

I think the idea is to allow the lightning energy to come down the rigging and dissipate into the water. By providing a convient path it bypasses your pricey electronics. Anyway, that the theory.

I believe some people throw a hunk of chain around the shouts and let it dangle in the water.

I’ve steel boats so for me it’s kinda built in.

[Mo Surprises]

Sounds like a sintered bronze grounding plate. Could be an SSB radio ground or general ground for corrosion and lightning protection. My SSB radio is grounded to mine as are other boat grounds. As an aside I have no problem with rapid zinc wasting but I do have a galvanic isolator on my shore power input.

[a64pilot]

A lot of Sportfishermen used to do that, the entire superstructure on one is aluminum tubing sort of like a radio tower, scared people of course so many fitted grounding plates and the superstructure was connected via a large cable, like welding cable size.
I believe it fell out of favor as it wasn’t proven to do anything.
Many thought if they were struck then the plate would blow a large hole in the bottom of the boat so they disconnected them.
But I don’t think that was ever proven either.

[Dsanduril]

It sounds like a Dynaplate or something similar. Here are the installation instructions for general reference.

As to whether or not you should have one, connect it, and to what

That's a subject fraught with opinion.

[YANDINA]

The theory behind the sintered plate is that water will penetrate the porous metal and increase the surface area contact giving up to 4 square feet of contact area for a 1 square foot plate. The problem with this theory is that no matter how good the connection to the water, any electrical current still has to pass through 1 square foot of water once it leaves the surface and the cubic resistance of the water is the limitation on conductivity, not the area of contact.

When used for lightning protection, a sintered surface provides millions of water filled cavities with restricted access that can turn to steam and explode when subject to lightning current, blowing the 1 square foot off the hull. At the incredibly high voltages involved in lightning strikes, surface area contact to the water is inconsequential and it would have no trouble blasting through an insulating surface of paint.

In view of the above, I decided to violate the instructions and paint over the plate once it dried out on the hard which seals the surface and reduces possibilities of corrosion.