Although I haven't experienced that type of maintenance cycle, I think I understand why. The pulse charging at 14.7 volts is like a pulsed equalization cycle. Not enough amps or long enough to boil out the electrolyte but I think that the theory is to eliminate sulfation.

But do your batteries have caps for checking the electrolyte? I would sure monitor the electrolyte level for a month or so to make sure it wasn't getting boiled off. And of course "boiled off" is just a colloquial term; it should be "disassociate electrolyte".

And don't your solar panels maintain the batteries at the dock. I wonder why you need a shore power charger.

David