This is how it works:
If you stay on the hook for two days and use, say 300 amp hours, then your batteries will be about half discharged and the resting voltage will be 12-12.2 volts. Hook up the 3 amp solar panels
and that voltage will rise to maybe 12.5 volts.
back to the dock
in or start your genset. The AC battery charger will be seeing batteries at 12.5 volts and will start its three stage cycle. It will first put out 20, 30, or near whatever its rated capacity is. The voltage will rise to about 14 as the batteries charge and will finally drop to about 13.5 in the third, float stage. The extra 3 amps from the solar panel won't matter much to the charger and it will do its thing just fine.
The 46 watt panel will really only supply enough amps to keep your batteries topped off. As the previous poster noted, 3 amps is higher than self discharge rate and practically speaking (depending on where you are located and how much sunshine you get) may put out 450 amp hours in a 100% sunny month and half of that in an average month. But if you use your boat every week or so, it should probably be ok with that.
But 46 watts is niether fish
nor fowl. Not enough to really do much good on the hook, maybe 15 amphours each day and too much to to top off with.
So, you have never said- what are you trying to do with these panels?