Originally Posted by Orchidius
I redid all wiring and nothing uses the hull as a negative atm. It's just the bloody engine
. The enginecontrols won't pose an issue either, but the mounts may (they're newly replaced, but I don't know if they have a bolt right through them connecting engine and hull.
There are two approaches with metal boats. Ground everything at one and one only point, or use a completely isolated negative system.
I understand you are doing the later and I believe it is superior.
Isolating the engine is quite easy. You need:
An isolated alternator
. (many are as standard, or can be converted)
Dual return senders (water temp and oil)
Rather than an isolated starter which is difficult to source) most boats use a large solenoid and briefly connect the negative to the engine during the time the starter motor
When the engine is running it is electrically connected to the hull, but not connected to battery negative. There is not any battery negative connection to hull other than the few seconds starting the engine.
It is important with this system to ensure isolation, dual CB are ideally fitted disconecting both the positive and negative side of unused circuits.