The voltage regulator is the last piece in the charging system for the battery. The stator generates an AC (alternating current) as the engine is running. That AC current must be converted to DC (direct current) because that's what the battery needs to charge and what it delivers to the engine for starting and to the accessories. That conversion is done by the rectifier which may be a separate part or it may be integrated into the regulator (thus it would be a rectifier/regulator). The regulator part of the system, as it's name implies, controls level of the output voltage going to the battery. Although we think of the electrical system on a boat as 12 volts, with the engine running, the voltage would typically be in 13 - 14.5 volts in order to properly charge a 12 volt battery.Some engines do not have a regulator but they do still require a rectifier. In those systems the voltage can run up to 17 or even 18 volts which over a long run could eventually damage a battery. So most newer engines and almost all larger engines have a voltage regulator. Now then to your service guy's statement about the trying to start the engine took out the solenoid because of the regulator. That's a bogus claim. When starting your engine the battery feeds current directly to the solenoid (essentially a very big switch) which is actuated when the key is turned to START. Current is not even passing through the regulator until the engine starts and then it would be in the other direction which could not take out the solenoid because it is not even actuated at that point. Yes -- your motor could indeed run without a functioning regulator but the battery would likely have gone dead (depending on how much you used the boat) because it was not being charged. I think this guy screwed up and is now trying to cover his tracks by placing the blame on you. For all you know, the regulator he showed you may not have come off your engine but is one he uses to cover mistakes. Keep in mind here, many "technicians" are not trained -- they have simply survived turning wrenches on boat engines. They have little or no electrical knowledge/training and events like yours happen way too often. But we have only your story to go with so unless we heard the story from the other guy, all of this is speculation on my part.
