Bonding and Electrolysis - AC Raw water pumps 220v

[boozubay]

We seem to have a consistent extra zinc wear on the port side in our 61MY. It has been like this for some time since we bought the boat. I have always wondered if the two AC raw water pumps cause this being the big variable from starboard and they run 24/7 since we live aboard.

I pulled out my schematics on the bonding and they do not show the bronze pump housings as a listed item being bonded yet they both are tied to the bonding system.

Has anyone ever had issues or guidance here? The shaft zincs go twice as fast on this side of the boat.

I saw something about minor ground leakage in the motors going to the bonding system?? I am tempted to just remove the bonding and test for a month to see what my divers report....

tks!

Dan

 

[racclarkson@gmail.com]

Anything docked on your port side? FWIW, I've had accelerated zinc wear for some time at my marina--always one side. Boats near me reported similar. Testing always showed me, and 2nd closest neighbor, in an acceptable range. The 70' Hatt docked behind me has now been gone for almost four months. My zinc life is now between 2-3 times better. The neighboring boats with accelerated wear cycled to other slips, so no comparative data there. I also had very uneven starboard rudder zinc wear until the big Hatt left. As a result, I doubled up on shaft zincs and went heavier on the rudders. That boat was an electrical nightmare. There was practically no bonding system in place, and a couple of the thru hulls were gigged on CG inspection as failure risk. The boat also burned up AC shore power connections and so on--long list. Interestingly, it's also an '83--night and day those two.

All things being unequal, you'd just about expect one side or the other to wear slightly differently. Mine have about equalized, and I'm really happy to have solved the mystery. About three years back I removed and redid the bonding to over 70 points per the original drawings, plus things added later. You can forget the multimeter on that job; just wiggle and watch the connections. That's when I found my AC raw water pump motor had a bonding wire on its casing. Don't know about your bronze pump housings, and I stand to be corrected, but using a bonding cable as an AC ground is a recipe for disaster--especially so below the waterline.

Anyway, that's my experience with your problem. Good luck.

 

[boozubay]

Thanks!
No boat on my port. We are side tied on a seawall. I also thought natural ground may be stronger???
Yes, both of my 220v bronze housings pumps are tied to the bonding strip with cables.... My original bonding schematics(yes I have all originals!) do not show that connection and am sure the boat came wire with AC.

 

[racclarkson@gmail.com]

Thanks!
No boat on my port. We are side tied on a seawall. I also thought natural ground may be stronger???
Yes, both of my 220v bronze housings pumps are tied to the bonding strip with cables.... My original bonding schematics(yes I have all originals!) do not show that connection and am sure the boat came wire with AC.

Seawall?? Made of?

 

[boozubay]

Concrete

 

[Photolomy]

Is your power isolated? That would affect one side more than the other (less water for the current).

 

[racclarkson@gmail.com]

Concrete

Time to start looking for stray current I reckon. There’s a good tutorial on boatzincs.com.

 

[Captain Ralph]

You can go crazy following stray currents.
You would be amazed how many A/C compressors leak stray ACv.
AND, My bread & butter, some meat head tied a isolated negative system or ACv green wire to the block or bonding system.
It may take you forever to trace it down.
If there is leaking rebar in a bulkhead, turn the ship around for a long test.

Hours of labor vs the cost of zincs???
Hard to justify over $100 per hour to maybe find the V leak.

Are you at a newer dock with one of those (F$%^%) fancy GFI service outlets?
Been to one of those docks?
This could be a tale of your ship vs ones around you...
Not conclusive but a good test.

 

[boozubay]

Funny you should mention the new GFI pedestal...They just put one in two weeks ago and the boat is suddenly eating up zincs...

The boat was using them unevenly as mentioned for nearly two years and now ate 4 shaft zincs in 1 month. Well nearly.... Two brand new zincs are down to 30% and two that were at 75% went to 20%. Scary fast. This is what started the worry.

Nothing changed and was happy to put zincs on every 3-5 months on the shafts but this got me very concerned for running rigging.... At this rate it could do serious damage. Considering I made no changes I am wondering if an ac pump making a bit of noise is leaking current now to bonding or is new dock pedestal. I removed both bonding wires to AC raw water pumps housings since they were not there on the OEM wiring diagram. They have been there for the last two years though. My divers are coming back in two weeks to inspect for me so will know if any of this helped. They removed the two 20% shaft zincs and put on new.

Going to try the fish and multimeter test this weekend..... Wish me luck hahah. Got to finish before Super bowl. It is here in Tampa after all.

I did find my two generator intakes both had bonding wires broken off and one was in bilge water of 1/2 inch. I measured .66v between the bonding and thru hull fitting. Maybe setting up for a strong stray current since bonding was broken? reconnected and now in milliamps.

Doing as much research and going to try to find what happened all of a sudden before calling in a very very expensive local ABYC electrician. He would still be cheaper than losing my running rigging! Before 5 grand for labor I can do a bit of testing on my own...

I like to know everything I can about my vessels... This issue is new to me for any boat to suddenly do this. Anyone seen new GFI pedestals do this having isolation transformers we have? Stray current must be DC in my mind.

Sorry for the long winded post... Learning and debugging as i would say in my computer world.

Thanks again to all for your input and brainstorming....

 

[Captain Ralph]

So, the new dock side GFI junk (if installed correctly) is pointing back to your own boat.
Strange it is now more an issue. Do you have galvanic isolaters or properly transformer isolated?

You have to isolate the leaking DCv from your bonding systems.
May take some decent rum to find the first trail.
Leaking battery chargers, leaking alternator diode packs, wrong strapping between bonding and ground cables and leaking bilge pump leads.
To help, your starters and alternators should be negative isolated from the block.
Green only to the block, black (from battery) to the starters and alternators.
Don't get confused when you see green and black tied together back at the buss in the power box. Here we know any current is not flowing per design on the green cable.
Also, your shore / genny transfer switch,, does it open close the green wire when on shore power / ships power? #1 boo boo here.

 

[jmooney]

If the problem is from bronze A/C pumps, you could change to plastic March pumps , magnetically driven ceramic impellers , no seals to leak , and dependable. I have been running the same two pumps since 2003 , virtually full time here in south Florida.

 

[boozubay]

I removed the bonding wires from the ac bronze pumps. This was not Oem. Running a zinc on a cable and going to run some tests to see if I can find anything.

My thought is the 2 bonding wires that were off the 2 generator thru hulls may be the issue along with the older ac pump.

will post findings as they come in

Tks for all the input

 

[JuiceClark]

So, the new dock side GFI junk (if installed correctly) is pointing back to your own boat.
Strange it is now more an issue. Do you have galvanic isolaters or properly transformer isolated?

You have to isolate the leaking DCv from your bonding systems.
May take some decent rum to find the first trail.
Leaking battery chargers, leaking alternator diode packs, wrong strapping between bonding and ground cables and leaking bilge pump leads.
To help, your starters and alternators should be negative isolated from the block.
Green only to the block, black (from battery) to the starters and alternators.
Don't get confused when you see green and black tied together back at the buss in the power box. Here we know any current is not flowing per design on the green cable.
Also, your shore / genny transfer switch,, does it open close the green wire when on shore power / ships power? #1 boo boo here.

Thank you for this.

The 52C I just bought has been going through zincs quickly and the batteries go dead way too fast unless all the breakers are off. Today I went through the bilge for 45 min with my meter set to ohms and couldn't find a reading anywhere.
But the boat is still at the seller's house while I go through the to-do list. He has a crappy old pedestal and I hope that's the culprit - would save me some trouble.

I'm going to check-out the genny switch next time over there.