The names Bond.... Or wait do I? (Beneteau 50 Electrolysis)

[boatpoker]

Originally Posted by zstine

I also tried isolating which circuit was the problem using a calibrated cell (i forget what it is called), and lifting bonds, but i got inconclusive results.

You refer to a silver/silver chloride half cell. All ABYC Certified Marine Corrosion techs will have one. It can be extremely difficult to track down these issues without one. They ain't rocket surgery but it does take a little education to use one properly.

https://www.koslow.com/silver-silver...20measurements.

[Bowdrie]

Originally Posted by RigBig

There is no such thing as electrolysis on a boat.

Originally Posted by boatpoker

First thing is never take electrical advice from someone using the word "electrolysis". That is uniformed dock talk using a catchy word.
"electrolysis" does not occur on boats. No one trained in Marine corrosion will use that word.

Au contraire, their is a special/certain realm of damage that can take place in wooden boats that most assuredly is a form of "electrolysis".
It occurs when a current, (seeking ground,) gets into a bonding system, or even to a single underwater fixture.
The current will hydrolyze, (sic,) the moisture in the wood, and break down the cell structure, causing the wood to "de-lignify".
Countless wooden boats have been severely damaged by people bonding and adding zincs to boats that never needed it.
It took many years before it was figured out that a wooden boat with all bronze fasteners/seacocks does NOT need any bonding whatsoever.
All they needed was a ground plate, separate, and not part of any bonding system.
Bronze, left alone, without interference, does quite well.
In the old days, a wooden boat, with bronze fasteners, bronze seacocks, bronze props and bronze shafts, would do just fine.
When builders started mixing-up metals, and adding AC circuits, that's when the troubles began.
So,, they started bonding and zincing,, still have trouble, add more zinc.
Things went downhill from there,,,.

[boatpoker]

Originally Posted by Bowdrie

Au contraire, their is a special/certain realm of damage that can take place in wooden boats that most assuredly is a form of "electrolysis".
It occurs when a current, (seeking ground,) gets into a bonding system, or even to a single underwater fixture.
The current will hydrolyze, (sic,) the moisture in the wood, and break down the cell structure, causing the wood to "de-lignify".
Countless wooden boats have been severely damaged by people bonding and adding zincs to boats that never needed it.
It took many years before it was figured out that a wooden boat with all bronze fasteners/seacocks does NOT need any bonding whatsoever.
All they needed was a ground plate, separate, and not part of any bonding system.
Bronze, left alone, without interference, does quite well.
In the old days, a wooden boat, with bronze fasteners, bronze seacocks, bronze props and bronze shafts, would do just fine.
When builders started mixing-up metals, and adding AC circuits, that's when the troubles began.
So,, they started bonding and zincing,, still have trouble, add more zinc.
Things went downhill from there,,,.

When I took my Marine Corrosion Analysis exam. They told us use of that incorrect term would be an instant failure ... they may have been joking.

In "electrolysis" current flows in the opposite direction to that which causes corrosion. it is a different process.

[girdasso]

You have not stated the materials of the thru fittings, keel bolts, propellor, propellor shaft, keel etc. If the thru fittings are brass get rid of them quickly and go to non metal. Then the advice to consult an marine expert in this sounds good

[boatpoker]

Originally Posted by girdasso

You have not stated the materials of the thru fittings, keel bolts, propellor, propellor shaft, keel etc. If the thru fittings are brass get rid of them quickly and go to non metal. Then the advice to consult an marine expert in this sounds good

Marlon is fine but bronze will also outlast the lifespan of the boat.

[goboatingnow]

On a European grp boat , fittings are never bonded together and don’t have dc negative connected to mains earth

My Bavaria 36 2003 had her skin fittings replaced two years ago by the P.O. I saw one of the fittings cut in half , it was perfect

European builders use DNZ brass. There never was a bronze shortage , it’s just not seen as necessary with GRP and European bonding practice

The P.O. admitted he succumbed to the “ fear “ mongering.!!!

Follow European bonding practice

Here is the Med , one of the saltiest seas around , fitting replacement is rare except after decades.