PaulRainbow
Well-known member
Most boats are wired as per the schematic i posted earlier and don't have an issue when starting the engine.Most boats now are not set up as the circuit in #66 which is why most people don't have the problem. It's not a case of a common negative point that all boats have, it's a case of a common section of negative cable shared by both circuits, which most boats now don't have since the prevalence of VSR's.
Despite your cynicism the Bedouin Theory is a real effect, although I like everyone else agree that it may not be the cause of the OP's problem.
This has been the case with bigger boats for decades. The vast majority of production boats are also wired like this.
If they were not, you would not be able to have a emergency parallel switch, unless it was double poled. You also cannot correctly install a battery monitor.