I have an old 311 sr1 and the volt meters will show into the red (16 + volts) for periods of time and then go back to 13.8. I assume I have a voltage regulator problem with one or both alternators. I further assume I am going to boil my battery (ies) if this goes unchecked. Anyone with experience? Am I right on the diagnosis? Should I check the switch (single Perko with off-1-both-2)? All of the wiring to the batteries seems sound. Thanks.

Might be something on the + side shorting to ground. Had a truck that had a + wire chaffing against metal and the voltage gauge would peg for a moment or two.

I've only had 1 incident where a regulator problem resulted in too much voltage. Check the guage first. If voltage actually is high just replace/rebuild the whole alternator. The cause of my bad regulator was due to an intermittand diode in the rectifier.
Gary