AC green to DC negative buss ?

[mcon12000]

Originally Posted by s/v Jedi

Yeah, DC ground… I’ve done away with it decennia ago

Yes and in this case you would tie the AC ground to the grounding bus not the dc negative bus.

[noelex 77]

Originally Posted by hjohnson

Except that you usually are through your engine. Unless your engine has both an isolated starter motor and an isolated alternator, your DC negative is going to be connected to the ocean. Even with a drivesaver, there's still an electrical connection through the heat exchanger and raw water pumps.

This is not true of many metal, especially aluminium boats. Typically the engine is connected to the negative supply briefly when starting, but is otherwise isolated.

[wholybee]

Originally Posted by hjohnson

Except that you usually are through your engine. Unless your engine has both an isolated starter motor and an isolated alternator, your DC negative is going to be connected to the ocean. Even with a drivesaver, there's still an electrical connection through the heat exchanger and raw water pumps.

It is not unheard of for a marine engine to have an isolated alternator and starter. My Volvo does. As a result, there is no anode for the engine or heat exchanger, and the prop shaft zinc lasts years, not months, even without a "drivesaver."

[s/v Jedi]

Without doing too much work, you can put an engine service switch in the dc negative instead of positive, much like I recommend for a windlass.

[noelex 77]

Originally Posted by s/v Jedi

much like I recommend for a windlass.

Yep. Flick off the circuit breaker and the windlass battery switch when not in use and you have isolated both the positive and negative poles. .