Stray current in marina

[Cadence]

Originally Posted by glcalahan

In answer to you quiry...the only connections on the engine are B+ and ground of battery. There is not one other electrical connection on the boat. BTW...the battery has been disconnected for 2+ weeks.

Thanks again!

From what you have said. Are the shaft and anode securely connected. What is your shaft made of? It almost sounds like you are creating your own battery from dissimilar metals not physically in good contact?

[boatpoker]

Originally Posted by Cadence

From what you have said. Are the shaft and anode securely connected. What is your shaft made of? It almost sounds like you are creating your own battery from dissimilar metals not physically in good contact?

It is highly unlikely that a galvanic (dissimilar metals) action alone would eat anodes in a couple of months. Something else is going on.

Call in a pro.

[Cadence]

Originally Posted by boatpoker

It is highly unlikely that a galvanic (dissimilar metals) action alone would eat anodes in a couple of months. Something else is going on.

Call in a pro.

It was a thought? Doesn't sound like he has much connected. Possibly he should disconnect his battery and see what happens?


Since he is not connected to shore power it does not seem like ground, earth, and water acting as ground would be the problem?

[AKA-None]

Post 12 says the battery has been disconnected for two weeks while post 1says the zinc is 2 months old. Where did the other 6 weeks go?

[rnor144]

Same thing here in Savannah ,Ga....
WW Williams ( supposedly the best engine repair service around )
We are on Salt Water.
But ....
They Put fresh water Zincs and drive shaft stuff , props instead of Salt Water Zinc.
I would have never discovered the damage but thank goodness for hurricane Irma when I pulled out again .......
Saw the damage that was done from just two months in the water after paying big bucks to them and Thunderbolt Marina.
I thought it was my fault being docked somewhere where there’s stray current. Never happened before so I was very confused. Thank you for the hurricane coming and I had to pull out the boat.
For you Amigo :
Look at who installed your stuff and if correct zincs and props were installed.

[Sailmonkey]

Originally Posted by rnor144

Same thing here in Savannah ,Ga....

WW Williams ( supposedly the best engine repair service around )

We are on Salt Water.

But ....

They Put fresh water Zincs and drive shaft stuff , props instead of Salt Water Zinc.

I would have never discovered the damage but thank goodness for hurricane Irma when I pulled out again .......

Saw the damage that was done from just two months in the water after paying big bucks to them and Thunderbolt Marina.

I thought it was my fault being docked somewhere where there’s stray current. Never happened before so I was very confused. Thank you for the hurricane coming and I had to pull out the boat.

For you Amigo :

Look at who installed your stuff and if correct zincs and props were installed.

Zinc is zinc. Good for salt.

However anodes come in other materials.

Aluminum for brackish and salt

Magnesium for fresh

[rnor144]

FYI:
Wrong zinc was placed on my drive shaft and props.
The company did replace and repair Their mistake.
Thank goodness 👍

[boatpoker]

We must learn to stop calling everything a "zinc". They are "anodes" of which zinc is one type.

Zinc anode for salt water only.

Magnesium anode for fresh water only.

Aluminum alloy (indium) anode for all waters.

[dkenny64]

rnor144,


are you saying they using the wrong type of anode?


as in Aluminum instead of zinc?


just trying to understand..
anodes are made from different types of metals...


-dkenny64
ps
I lost 2 zincs( yes zinc metal in 4 months)..another story..another time

[leftbrainstuff]

Originally Posted by Neptune's Gear

Nope. This is almost certainly an issue on/from your own vessel. You need a proper silver/silver chloride anode to measure it correctly. For the issue to be the marina, you MUST have a circuit to said marina - a shore power connection is the most common, but it could be a chain leading ashore etc. You have no circuit, only the water.
you need to find the electrical leak on your own boat. Bilge pumps in the water are a common source - is your bilge dry? Get the right gear to test, or employ someone to do it.

A piece of silver is a good silver reference electrode substitute.

I suspect you have a ground issue. It's much more complicated on a boat as you probably have a DC ground, AC ground and Seawater ground. Connecting these incorrectly will often lead to issues that you describe. You may alao have lightening and RF grounds.

Don't forget to check the shore power side. Helped a fellow boater resolve a stray current issue last year in a brand new marina with fancy stray current detection at each pedestal. The marina side was incorrect. The lesson here is make no assumptions but measure every system.

It's just a process of elimination.

[rnor144]

You guys are exactly right.
They used magnesium anodes and not zinc for a boat in salt water.
It was the answer as to why everything was corroded after 2 months.
I would have never known except a hurricane named “Irma” made me pull her out on the hard.
But to their credit they did replace , hopefully with “Zinc”.....
I’m learning by all my mistakes 👍

[glcalahan]

Thank you again Hellosailer!

No TV, no telephone and literally no hook ups anywhere or battery switch is installed yet. I will be installing all I mentioned here but I have only torn everything out. Remaining few wires are disconnected so I can pull new wire. The boat sunk 6/7 years ago and PO did remove and pickle tje Yanmar. I pulled the Yanmar and rebuilt it. So yes it is a fundamental new wiring. I suspect it is easier to do than fix a mess and the wires had corrosion tryout hence the re-wiring.

I will be installing a 6 lb zinc until I can sort this out. The bronze 14" 3 bladed prop and the 7/8" SS shaft are new. The PO had no Zincs and 2 of 3 blades were gone from electrolysis when I got the boat.

[chollapete]

@boatpoker: Thanks for that distinction. My takeaway is that electrolysis is essentially a battery being charged while galvanic is a battery being discharged.

[boatpoker]

Originally Posted by chollapete

@boatpoker: Thanks for that distinction. My takeaway is that electrolysis is essentially a battery being charged while galvanic is a battery being discharged.

NO !
Electrolysis has nothing to do with it unless your intention is to deconstruct the sea water into it's basic chemical components. Absolutely no application of the word "electrolysis" in relation to corrosion, it is an unrelated process.

You are dealing either STRAY CURRENT or GALVANIC CURRENT ..... ONLY.

[glcalahan]

Originally Posted by AKA-None

Post 12 says the battery has been disconnected for two weeks while post 1says the zinc is 2 months old. Where did the other 6 weeks go?

Thank again!

Good point and thanks!* The boat went into the water May 18, '18.....3 weeks ago I moved the battery and spent several weeks with engine disconnected while I built/glassed a new battery tray for the new AGM 31.* Battery was and still is disconnected.* Another poster wondered about the new shaft metal.* The new shaft is SS and the new prop is bronze.* I just used what I believed to be original.