That means your alt is putting out 14.2V+ and the battery is seeing just 13.0 volts and is being chronically under charged. I have physically measured voltage drops of 1.2V volts or more at just 10A of charge current through these circuits. Another alternative is to run your alternator direct to the house bank with a fuse or breaker within 7″ of the battery and then add a combining relay or Echo Charger.
IMPORTANT: If you have an ammeter in your engine panel remove it and jumper your alternator 6″ over to the starter post with heavy wire.
It amazes me how many boats are out there still using this amazingly unsafe set up. The factory wiring, with an ammeter in the panel, is flat out dangerous and this wiring mess really needs to be addressed. If your Universal engine panel looks like this, and has an ammeter, you are due for some critically important wiring upgrades.
