Grounding anodes

[Gsherwood]

Do these do any good? Isn’t the boat grounded to the water through the zincs?

https://www.boatid.com/martyr/7-7-l-...uR91rO7Os4WvfQ

[Pcpete]

Yeah, Glen, I’m kinda skeptical about those too. However, if I had a leaky old boat nearby where the bilge pump spent more time on than off, I’d consider one. The risk is having too much anode, which sounds odd, but can be just as damaging as not enough. Anyone that I heard of that used one only used it in port, and only when there was an inordinate amount of power in the water. Whether it was an electricity leaking boat or the power supply at the dock, measuring the electrical currents in the water around your boat in different locations will determine if you have enough anode to protect your boat. Fortunately, I store on the hard so electrolysis in the water isn’t an issue. However, I still check the grounding of the shore power to the boat to make sure it’s working correctly.
BTW, if you haven’t inspected your bonding system and included unwrapping the black tape at the connections, you may want to do that. I started looking at mine and in many cases the corrosion was the only thing holding the wires to each other. Yeah, I replaced the bonding system.

[hoodbay]

That is a Zinc alloy Anode which is used to prevent Galvanic corrosion and will only work if you have an intact bonding system that connect your underwater metal fittings...
It is not for Grounding...

This may help.
https://www.seashieldmarine.com/zincs-boat/

[Kwood]

What hoodbay said
Hanging anodes are used when you have insufficient protection already attached to the bonding system installed below the water line. Like if you travel from salt to fresh water for any length of time, or if existing anodes get eaten by stray current at a dock or passivated and you want immediate protection.

I keep one on board. I also have a silver chloride half cell with my tools. If I travel to a new marina I will check my bonding with the half cell. If there is stray current, I know it right away.

You do not want your struts dissolving.............

[Gsherwood]

The hanging anode needs to be tied to the boat ground to work right?

[Kwood]

Not the battery. The bonding system that your hull anodes are attached to. Generally 6 gauge green insulated wire.

[ksanders]

My opinion is that you really want to isolate your boat from other boats around you, so that their stray current cannot pass through your boat and your shore power cord.

How do you do that??

Simple... Install an isolation transformer.

[Kwood]

I've considered an isolation transformer. It is install and forget about it installation which is good. But it isn't cheap.

The attachment is what my insurance company has to say about stray current.

[ksanders]

I've considered an isolation transformer. It is install and forget about it installation which is good. But it isn't cheap.

The attachment is what my insurance company has to say about stray current.

I just happened to have my ice maker out to pull a cable... so here is a photo of the two isolation transformers that I put in two years ago and as you indicated forgot.

[MonteVista]

Isolation transformer may be an ideal solution, albeit expensive. You should add a galvanic isolator on the GND wire to prevent small (i.e. leakage) currents flowing through the GND wire. Hanging anodes are better than not having any anode. Hanging anodes to NOT prevent current through your metal parts (e.g. prop) but lessen that. Finally, most (but not all) leakage current issues occur between two boats and travel through the GND wire of their AC connections to shore. Thus, when not using shore power UNPLUG your shore cable.

Good luck