Zinc Consumption Normal?

[Newtrawlerowner]

I have a 2003 MS 400 in salt water. It seems my zincs don't last very long and wanted to ask what others have experienced. I use aluminum shaft and hull zincs. I just replaced the galvanic isolator with a Pro-Safe 60 amp unit. I also tested this unit several times and it is working. I've tested the bonding system, found some poor connections and corroded wiring and repaired. I also found my shore power cord had some internal corrosion allowing leakage from the ground (green) to power. Not enough to trip the shore power breaker. I've tested the shore power pedestal and no issues there. My 1st question is how often do you replace underwater zincs?

 

[DavidM]

In full salt water (near the ocean) I had to replace mine every 6 months. In brackish water, maybe every year.

David

 

[psneeld]

Depends on so many thing it's impossible to give advice versus just ones own experiences.

I have had boats and or locations that 6 months was normal. My current set up, shaft zinc could probably go 2 years, the rudder zinc a year plus depending which weight I put on,, and the transom plate zincs between a year and 1.5 years depending which weight I put on.

All my zincs are considered "zincs", not Al or Mg.

 

[Comodave]

I have a 2003 MS 400 in salt water. It seems my zincs don't last very long and wanted to ask what others have experienced. I use aluminum shaft and hull zincs. I just replaced the galvanic isolator with a Pro-Safe 60 amp unit. I also tested this unit several times and it is working. I've tested the bonding system, found some poor connections and corroded wiring and repaired. I also found my shore power cord had some internal corrosion allowing leakage from the ground (green) to power. Not enough to trip the shore power breaker. I've tested the shore power pedestal and no issues there. My 1st question is how often do you replace underwater zincs?

I understand that you are using aluminum anodes and not zinc anodes. Are all of the anodes aluminum? They should all be either aluminum or all zinc, not mixed. How long are they lasting, getting down to about 50% consumed? Are you in a marina? It could be a nearby boat causing your anodes to waste away. If the anodes are going away really fast you may need a certified marine electrician that is experienced in corrosion to check the boat out.

 

[GoneDiving]

How long are they lasting, getting down to about 50% consumed? Are you in a marina? It could be a nearby boat causing your anodes to waste away.

+1 for this. When I bought my boat it was kept at a marina and the 1yo zinc's were basically at end of life. I motored home to an unpowered pole mooring and 12 months later when I slipped the boat the zinc's were no worse. Being away from other boats and power sources effectively stopped the loss of zinc.

 

[Bacchus]

How did you measure hot to ground leakage and what was the level?
Marina pedestals must be older and not latest code or they would have likely tripped.
I think latest code is 30 miliamp difference hot to neutral will trip.
I would change cords and recheck.
You may need an experienced marine electrician (not household)

 

[rgano]

How are all those anodes in the engine doing? AL as well?

 

[SteveK]

I will just add "To Bond or not Bond" that is the question.
After two years my zincs still had life but changed them anyway.
I only bond the shafts, shaft mounts, prop to transom zinc. Shaft also carry two each zinc. Nothing on rudders or through hulls. The engine/trans is isolated from shafts so even if AC power were to stray it would stay aboard.

There are two schools for bonding,
1) connect it all together, bond DC- to AC GND
2) don't bond everything.
Electricity needs a circuit, bonding provides that circuit.
But of course there is ABYC opinion... to consider

 

[Comodave]

How did you measure hot to ground leakage and what was the level?
Marina pedestals must be older and not latest code or they would have likely tripped.
I think latest code is 30 miliamp difference hot to neutral will trip.
I would change cords and recheck.
You may need an experienced marine electrician (not household)

It is 30 mAmps for individual slips or 100 mAmps for a dock on one ELCI.

 

[Bacchus]

It is 30 mAmps for individual slips or 100 mAmps for a dock on one ELCI.

Dave
I thought 100mA is for all slips fed from a
distribution panel?

 

[Comodave]

They are wiring a dock with one 100 mAmp breaker to do it cheaper. Then they wire individual slips with 30 mAmp breakers when cost isn’t as much a concern. What is bad is when the boats on a dock are all leaking a bit but maybe total 95mAmps and then you hook up and leak 6mAmps and suddenly you are the bad guy when the whole dock shuts down.

 

[SteveK]

Dave, what does the 'm' stand for in 100 mAmp?
I read it as milliamp, 100 mAmp = 0.1 Amp

 

[Comodave]

Dave, what does the 'm' stand for in 100 mAmp?
I read it as milliamp, 100 mAmp = 0.1 Amp

Yes.