Volt meters jumping

[Fastphil]

I have 2 new alternators, just got the boat. I noticed that both volt gauges on the dash jump from 14, down to 12, then back up. This is happening on first start up and maybe an hour to two after. They stay more on 14 than 12. Is this the intake heaters I hear so much about? I'm sure this can't be normal. All batteries have been checked and load tested and are good. Both alts are new, one by the seller and one by me. Have taken her out twice so far and did it both times. Any ideas? Oh, and btw, on one trip, the port gauges went coocoo, tach dropped to zero,volts too. I hit the emergency start button andIt all came back. Engine never quit.

 

[endless seas]

Pre -heaters ???

 

[Steve Franklin]

Fast Phil, not to worry about the readings on the alts. This is the pre heaters mine does the same thing. Can't help you with the other gauge problem. You made a good choice on the 420 with the Cummins, I love mine. Enjoy Steve