Bronze grounding plate conundrum?

[DesertAlbin736]

On recent lake outings I noticed a small but persistent hull leak had developed that was allowing small amounts of water to get into that engine air vent space in starboard side of the engine bed where those rectangular holes are in the vent channels that lead to the deck vents behind the after & spilled over into the bilge. At one point I opened up the engine box to do a quick check & found a couple inches of water in the bed under the engine. I was all like WTF is this about? It wasn't fuel, it wasn't antifreeze, it wasn't coming from the raw water pump or through hull & it wasn't leaking from the fresh water tank (I fixed that issue previously). It wasn't leaking from the black water holding tank. With the boat on the trailer & parked at my house I hooked up my bucket & raw hose rig to run the engine for a bit looking for leaks & saw no sign of coolant or raw water leaking. While on the water another time I could see a small trickle of water flowing from under the front end of the starboard bench seat locker. With my recently installed automatic bilge pump sensor the pump would kick on several times a night while we were at anchor. But since the batteries are now in that locker, having been relocated there as a result of my holding tank upgrade project, I could not access that space without pulling the batteries out. The two items that occupy that part of the bottom under the batteries are the depth sounder transducer and a sintered bronze grounding plate through bolted to the outside of the hull & connected to the engine bell housing by a heavy gauge battery cable. The grounding plate also happens to sit right on top of the trailer bunk when the boat is out of the water, hence it gets beat up. Since I wasn't able to remove the batteries while the boat was in the water I pulled the batteries after the boat was back on the trailer, which by that time I really couldn't tell for sure if the water was coming in through those through bolts that attach the grounding plate or from the transducer. But I'm pretty sure it's not the transducer leaking.

So here's what's left of the grounding plate after removal. It measures 8 inches long of what once was a 12 inch plate, the ends having broken off long ago, most likely well before we took ownership.

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Here's what a new one is supposed to look like, 12 X 3 X 1/2" thick. For reference the bolt holes are spaced at 6 inches on center, identical to the existing one. The best price I could find on a new one like this was $217 + shipping.

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So the question is, do I really need to replace it with a new one or should I just seal the holes up with epoxy and forget about it? From what I've been able to find & read about it the only real reason to need one of these is to provide an RF ground plane, aka "counterpoise", on HF/SSB radios & not necessary for VHF. For lighting protection it wouldn't do all that much to help since "sintered bronze" is meant to allow it to absorb water to virtually increase its effective 'ground plane' square footage. . In which case the massive currents induced by a lightning strike could cause the water absorbed by the plate to instantly turn to superheated steam and blow a hole in the bottom of the boat. In which case with no easy access to that space we'd soon be treading water while watching our boat head straight for Davy Jones' locker. In which case it wouldn't make much of a difference with the sail mast installed.

https://aqualitz.ca/index.php/marine-grounding-systems/

When it comes to AC grounding I brought my shore power AC system up to ABYC code a few years ago, installing a new double pole ELCI breaker panel, a galvanic isolator in series with the green wire right after the service inlet, and connected the green wire to the AC breaker & DC ground bus as recommended. Also put a household GFCI outlet in my 15A outlet circuit with two other outlets on that circuit. Also added hard wired a new on board "smart" AGM compliant battery charger direct to its own 15 amp circuit & breaker. The idea of "bonding" all through hull fittings is passe since stray DC currents in "hot" marinas could only accelerate induced galvanic corrosion.

Any thoughts & advice?

[SalishAire]

My only claim to expertise in this is as a person who lived on a boat for 7 years with a HF radio. I cannot think of any reason that there should be a ground plate on a small boat like an Albin and even on Salish Aire we abandoned the plate that came with the boat (it was left in place but always a point of concern because of the through bolts) and a KISS counterpoise system used instead for the radio. I would seal the holes if I were you.

[DesertAlbin736]

I would seal the holes if I were you.

Thanks Norman. That's exactly what I'm going to do. Plug the holes with Marine Tex type epoxy & glass over the inner surface with patches of either woven roving or chopped strand mat.

You need to come down here to discuss in person. Our weather is sunny & 70s every day except for next Thursday night & Friday when we're expecting a 60% chance of showers & our highs dipping to the mid 60s. Our lows have been around 60 but now we're into December they'll dip into the 40s. No sign of frost or freezing temps. It's been so long since we've seen a drop of rain I can't remember.

Oh, and about the ELCI breaker, the ELCI acronym stands for "Electrical Leakage Circuit Interrupter".

[Norseman]

I had a plate like that on my sailboat. Installed it myself, hated to drill 4 holes under the water line but liberal amounts of 5200 made sure there would be no leaks and no problems. (except for the next owner trying to remove the plate)

Have heard unconfirmed rumors that a lighting strike could blow out the plate, including the fiberglass behind it.

The SSB served us well in the Bahamas for many years, but have no plans for one of those on my Albin 28TE.

[LopezMike]

I had one of those plates for years on my 36' sailboat for the ham radio. It worked fine and was just below the waterline for ease of cleaning. When i got back from wandering and unloaded all of the damned extra stuff out of the boat, the plate was above the water line. Hmm.

So I removed the plate and grounded the radio to the rudder post with a flexible braid strap. The radio worked just as well. An arrangement I use now on my A25.

I suspect that those stories about lightning damage are just that. Stories. Between the boat spending much of the year on the trailer and living in an area where thunderstorms are very rare, I'm not concerned.

Mike Colyar
A25 Caprice

[SalishAire]

Mike Colyar: Just curious as to what you use for an antenna if you are playing in the HF range. My wife would certainly role her eyes if she knew I was even asking (but she is also a licensed ham operator so less so than other wives). I'm not thrilled at putting a 23' vertical antenna on a 25 ft boat but might consider a shorter (but much less effective) style device such as we have on the Airstream. I would definitely go back to a KISS counterpoise which is made just west of you in Point Roberts.

[DesertAlbin736]

Update:

Plug the holes with Marine Tex type epoxy & glass over the inner surface with patches of either woven roving or chopped strand mat.

Since writing that I pulled out my copy of Don Casey's "Sailboat Hull & Deck Repair" book, and in the chapter about epoxy laminations (bonds to existing f/g surfaces better than polyester resin) says not to use chopped strand mat with epoxy resin but use woven cloth instead because the binders in chopped mat react adversely to epoxy resin. Also put down a first coat of resin thickened with colloidal silica to catsup consistency before adding layers of cloth to fill in the unevenness of the woven roving surface. I have a little less than half of a 1 qt can of West System 105 resin left from previous jobs, which for a small job like this should be sufficient for several layers of cloth on a pair of small 2 inch square patches of cloth laminate. The 3/8th inch drill holes themselves will be plugged with Marine Tex epoxy putty, with the f/g cloth laminate patches over that on the inside surface. Haven't started the job yet since I've been busy with holiday stuff. Temperatures here are still warm enough, >60 deg, to do the layup, and if needed can plug in a small electric heater to warm up the area. Just have to prep the surface properly first.

Mike writes:

I suspect that those stories about lightning damage are just that. Stories. Between the boat spending much of the year on the trailer and living in an area where thunderstorms are very rare, I'm not concerned.

At one point way back in one of La Dolce Vita's previous lives she was home ported for a time somewhere in South Florida. That could be why they added a grounding plate, since Florida is just about the lightning capital of the world.

[LopezMike]

Norman,

I use a regular 22/23 foot SSB whip. No special mount needed. Just clamp it to a rear railing upright with two S.S. hose clamps. The outside of the whip is non-conductive. The original 1" thread base mounts just break all of the time. There is a clamp and a 1/4 - 20 stud just above the bottom of the whip and I just run a fairly heavy gauge (#14/12) wire with normal thickness insulation from that stud to the autotuner which is hidden under the plywood under the aft cabin mattress. A length of heavy braid to the rudder post completes the R.F. part of the installation.

I won't be back from Baja until Spring but if you don't do your installation before then, I have a big reel of silver plated 1" wide braid. Stops corrosion. Otherwise a replacement automotive ground strap with drilled lugs on each end works fine.

There is a direct relationship with the hideousness of antenna and it's performance.

Before you bother with buying a new whip, ask around at marinas and boat repair operations about used and discarded ones. They get all sun rotted and itchy on the surface and get replaced. Ten minutes with a hose and some 400 grit sandpaper followed by some paint and you end up with a new unit. Mine doesn't look too horrid painted white.

The top 9' of these whips is an ordinary F.G. CB whip with a 3/8" - 24 thread. It will need reconditioning too.

Understand as well that it is necessary to take this beast down when there is limited overhead clearance. Like when towing behind the truck. Don't ask.

Spent my life from six months old until ten years ago in Olympia. Hamming since 1959. I've had the same phone number for 75 years. Creak!

Mike Colyar K7ITL
Lopez Island, WA
Caprice A25

[DesertAlbin736]

Mike,

I replaced my VHF whip antenna with a new 9 ft Shakespeare earlier this year. The sun tears things up here, including the coax cable. No SSB or radar on this boat. It mounts on the starboard side of the doghouse just under the back end of the side window & I always fold the antenna down for trailering.

I'm not a ham operator or anything like that, but my late grandfather, BSEE Penn State class of 1915, worked for RCA Communications from its inception in 1920 until his retirement in 1957. For most of his career from 1921 he was "engineer in charge" of the RCA Tuckerton long wave wireless telegraph station in Tuckerton, NJ until its decommissioning in 1949. Said station was taken over by the US Navy from a commercial German company in 1917 during WW1 and was rumored to have transmitted a "get Lucy" message regarding the Lusitania sailing. It was demolished in 1955 and is now the location of Mystic Islands waterfront community.

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