Grounding plate, source/ necessity?

[Patrick of M]

My boat had a couple of dynaplates that were bonded with everything.

During the refit one broke and the other last looks rough.
Also dynaplates are problematic for lightning dissipating.
I think I would prefer a rectangular oxygen free copper grounding plate (I think 6"x 2 ' is the spec) bonded to a lighting rod on the mast.
This boat was hit before and it took out all the electronics.
I'm going stand alone, as much as possible, with BLE comms or wifi when possible, but still a hit will suck.
Reading and searching on this situation can't tell if a grounding plate is still a thing and also sourcing one seems a little difficult.
Thoughts?

[s/v Jedi]

Originally Posted by Patrick of M

My boat had a couple of dynaplates that were bonded with everything.

During the refit one broke and the other last looks rough.
Also dynaplates are problematic for lightning dissipating.
I think I would prefer a rectangular oxygen free copper grounding plate (I think 6"x 2 ' is the spec) bonded to a lighting rod on the mast.
This boat was hit before and it took out all the electronics.
I'm going stand alone, as much as possible, with BLE comms or wifi when possible, but still a hit will suck.
Reading and searching on this situation can't tell if a grounding plate is still a thing and also sourcing one seems a little difficult.
Thoughts?

When a lightning rod successfully diverts a strike to ground via the bonding plate, your electronics are still taken out because of the EM surge.

Your best bet is a bonding system to protect the integrity of the boat hull, deck, seacocks etc. which is done with a bonding plate under the mast and a vertical 6AWG cable from the plate to the mast.

With this (bonded mast) in place, you can try to escape a hit altogether by installing a static dissipator at the masthead.

Also, for near strikes, you can protect electronics by isolating the equipment that is likely to be struck, like a wind instrument, VHF radio etc. For wind NMEA data you can use a wifi bridge as air gap. For power supply to the VHF radio you can use a separate small (motorcycle) battery with an isolated dc-dc charger. Here you must make sure that the radio ground does not have a galvanic connection to the main DC negative (which means DC negative must not connect to the lightning bonding plate)

[GordMay]

Yes, a lightning grounding electrode is still necessary.

What you’re seeking is a high conductivity, solid [not laminated], copper* [or silicon bronze], busbar, with a minimum of 144 square inches, in salt water, ‘more’ in fresh.
The most recommended lightning ground electrode is a long strip, perhaps 4" wide x 1/4" minimum thick, and 36" minimum long, with the ends secured with two fasteners, to prevent “twisting”, under dynamic loading.

Cu. busbars are readily available from metals suppliers, and [less so] from electrical wholesalers. I used to be the only, one of 6, elect. wholesalers, in Thunder Bay, to carry them. Ours were 8' or 10 Ft long, but we didn't cut them.

* UNS C11000 grade oxygen-free copper [99.90% pure Cu.]

Dr. Ewen M. Thomson has patented a new electrode geometry, claimed to be more effective.
➥ Marine Lightning Protection Inc. [lots of excellent lightning information]

EwenT ➥ https://www.cruisersforum.com/forums...went-7173.html
Posts by EwenT [25] ➥ https://www.cruisersforum.com/forums...rchid=38517040

[Bowdrie]

The Dynaplate was designed to be a ground plane for radios and evolved into use as a termination point for bonding systems.
A billion BBs bonded together gave a large surface area in a small package, but the matrix that holds all the BBs together isn't really designed to withstand a lightning strike.
A bolted-on keel works pretty good, short heavy cable with as straight of run as possible going to mast step or compression post.