Is this BS?

[Hoolie]

[ QUOTE ]
... an insulated earth ...

[/ QUOTE ] That's right - and the engine will be isolated too. Our boat has relays to temporarily earth the engine for stop solenoid and glow plugs. If you don't properly earth the engine using an automotive alternator the diodes/regulator will be wrecked.

 

[pampas]

The main difference with a marinised Alt is that the end cases are painted with a baked anti corrosion paint the rotor and stators have higher spec. insulation and all iron work is of a different composition than normal(The spray paint I mean).Diode packs may be treated as well. this applies to most alt for the marine trade whether they be neg earth or fully insulated. In the case of the Lucas range most components are inter-changeable with a standard model,but some other makes require you to buy the marine spec as holes will not line up properly. I trust that this sheds some light on the subject being discussed.