Fitting battery charging advice please

[B27]

The engine is not always connect to the water and DC zero is not always connected to the engine block, so routinely using either is not reliable. Most modern engines have flexible couplings, for instance.

There is no need to have everything double insulated, you're just making things more complicated than they need to be.

It's really, really, really simple. All onboard Earth points are connected together, the shore power Earth and the connection to the water are both connected to this circuit. The connection to the water can be made in several ways, a connection to the hull of a metal boat, and Earthing plane or an anode. If the engine block is connected directly to the water via the shaft and prop, that could be used too, DC negative is irrelevant, electrical continuity to the water is all that matters.

FYI fitting shore power systems is part of my day job.

I'm confused now as to whether you're saying a battery charger connected to a camping lead, without an earth connection in the boat is OK or not?

 

[PaulRainbow]

I'm confused now as to whether you're saying a battery charger connected to a camping lead, without an earth connection in the boat is OK or not?

That's because i did not say one way or the other, i didn't suggest camping leads, i suggested a fixed shore power installation and that's what i described in post #59, or at least the Earth part of it.