Zinc Anodes for Protection from Neighbors

[Tom Ipock]

I am familiar with how zinc anodes work to protect your metals by sacrificing themselves. However, I have long been told that by putting a large hunk of zinc in the water by your boat, it would help fight the electricity being sprayed into the water by a neighboring boat or the docks.
My question is - does this piece of zinc need to be connected to the ground system of your boat, or just be dangling in the water adjacent to your boat?
For the next few months, I am docked next to an old wooden boat that has no bonding system at all, and I am sure that I need to do everything possible for my protection. Any help would be appreciated.
Tom

 

[Genesis]

If you have an isolation transformer then it doesn't matter - there is no path from the other boat to yours electrically.

If you DON'T have one, then the zinc has to be connected to the system ground, otherwise it does nothing.

 

[Tom Ipock]

I have two large transformers in my generator room - Are they "isolation transformers"
Tom

 

[Genesis]

Probably.

Can you take in 110V from a dock cord and use 230V items (within the current limits, of course). If so, that's an absolute test for "yes".

 

[first230sl]

I have an isolation transformer (which I love), but still seem to be going through zincs in about 5 months - which, I imagine, is too short for comfort. I assume this likely implies a stray current leak to the bilge or bonding circuit - correct? Time to get out the multimeter.

Back to isolation transformers for a sec - I get the basic idea of how an isolation transformer works, but does anyone have access to a nice description which shows the various windings and connection to shore-side and boat-side circuits? I understand how a transformer can give me 240 from 120, and believe I understand how it can produce one leg 180 degrees out of phase (by having one secondary wound in one direction and another secondary wound in another direction). But how does it happily do so regardless of whether the primary side is 120, 2 x 120 out of phase, or 2 x 120 in phase?

I'd love to see a description.

Take care - Murray

Probably.

Can you take in 110V from a dock cord and use 230V items (within the current limits, of course). If so, that's an absolute test for "yes".

 

[Genesis]

You likely have a stray current leak, yes. Check all your DC wiring, particularly anywhere where it can get moist/wet, such as in the lazarette.

Its hard to draw decent ASCII stuff in forums like this..... I'll see if I can figure out a way to do it...