old attempt at lightning protection?

[Rainh2o2]

I recently bought a '74 Catalina 25. When I bought it I noticed there was a plate or patch on the port side about midway of the boat underneath what looks like about 2 foot below the water line. The previous owner told me he thought the plate was an old patch that someone (not him) had put on to stop the thru hull on that side from leaking. Upon further examination tonight to see what it was going to take to get the head working, I noticed a heavy gauge wire (size 4 maybe?) leading from what looked like a grounding lug on the port side, beside the waste tank, up to the mast step. I have the boat pretty well covered in heavy tarps and didnt uncover it to look but the wire went right up through the deck where the mast sits. Anyhow, when I was looking at the thru hull I noticed that it wasnt capped off. I went outside and looked at the "patch" and it wasnt even really near the thru hull, in fact it was closer to where the ground lug I saw inside was. Is this normal to have this on this boat? Should I just eventually remove it? From the outside it looks like a plate thats about 6 inches wide and a foot long with what looks like a carraige bolt through it in the middle. The plate is coated in bottom paint, which is new this year, so I probably wont mess with the outside plate this year.

I know lightening protecting is a very controversial subject so I am not asking if I should make sure its connected or not, I am more just wanting to know if its an add on from a previous owner or factory installed.

[mitiempo]

Definitely not factory installed.

[cal40john]

Does is look anything like these dynaplates?

Dynaplate


Sintered bronze for lots of surface area for a radio ground.

At one point people were installing them as lightning grounds, but reports say they don't work well for that.

I'd have chosen the keel for a lightning ground on a boat with an external keel.

[campuscab]

Sounds like a RF ground for the radio. It makes the antenna work better.

Sent from my Huawei Y301A1 using Cruisers Sailing Forum mobile app

[psk125]

Sounds like a lightning dissipator sheet to me. They're often circles about 2' in diameter. I've been in lightning storms on Lake Michigan; they can be plenty scary. You dont want a lightning bolt to melt the conducting wires and blow a hole in the boat if it can't get to ground fast enough and picks a through-hull for it's route.

[edmcctn]

so during rebuild of my old wood boat, I will take much said here to hart. thankx

[Rainh2o2]

Thanks all for the replies. After some long research on catalinas I found out it is aftermarket, Dont know if its lightning protection (I suspect it is) or radio ground, but I am going to disconnect it. Maybe next spring I'll think about removing it, although if the bottom paint holds up I may leave it until then. It has a hole through the bottom that looks like about a 1/2 inch bolt holding it thats under the paint but shows no signs of leakage so thats something I will keep an eye on. That was another thing, if it was painted over, then it couldnt have been doing much good for protection, or even ground, unless the bottom paint is conductive, which I have not tested with a meter, meh, anyhow, thanks again

[Nicholson58]

Originally Posted by campuscab

Sounds like a RF ground for the radio. It makes the antenna work better.

Sent from my Huawei Y301A1 using Cruisers Sailing Forum mobile app

Radio or hull ground plate is what I was thinking. In either case, it should not be painted.