I don't understand where your coming up with 22 to 33.3 Amps (OK I think I do, but I also think you are doing it wrong).
It's all about the Watts. Watts is power, Watt/hrs are storage (simplified I know).
Look at it this way, you have 8ea 100 Watt panels, so a max total possible input of 800 Watts.
If you divide 800W by 48V, you get 16.66 Amps, and 800/72 = 11.11 Amps. But whatever Voltage your panels are putting out, the max Wattage is still 800.
So for me, I look at Watts needed for a given speed and then Watt/hrs left in my pack, to determine how far I can go.
Another thing to think about is power loss to conversion/heat. In your example using the theoretical max of your solar panels of 800W, your going to loose a little at the controller (The Victron 100/20/48V claims 98% conversion efficiency) so 800x0.98=784. So now your only getting 784W to the battery (assuming no voltage drop from the wires, and there are ALWAYS voltage drop from wires). There is also some loss at the battery itself.
I can tell you from experience that putting 100W into a battery for an hour does not net you a 100W/hr charge. I have Watt/hr meters at my batteries that count up from zero when using, and back down when charging. When fully charged the count will always be negative (until I zero them). As far as I can tell, my battery loss is around at least 0.5% (small but still relevant). So now you are down to about 780W.
If you add in the fact that you will also never see the full 100W / panel (unless you are in laboratory conditions) you should always factor in some loss before hand, then later measure when your system is operating.
You should also be careful when having 2 different batteries that you use independently. You would need to turn the discharged (used) battery off before turning on the charged (un-used) battery. If you connect two batteries with different voltages together, you will probably see some smoke, and need some new wires (unless you have the fuses and circuit breakers needed). This is just a guess of course, because I have never, ever, ever, ever, ever, done such a thing (did I protest too much?).
And you would also need to separate the charging system from each battery.
I have my battery banks hooked up to bus bars and use them all at the same time. The solar and shore power chargers AND ALL loads are also connected to these bus bars. The solar charge converters are always on so when the sun is shining all the solar power is being used first. If the batteries are full and the load is small, the solar controllers limit the output to just enough to run the load. If the load increases then the controllers increases the output to match until the load becomes more than the solar is providing (or a cloud passes over) then the load starts drawing from the battery, but only for the excess load above what the controllers are providing.
Then if the load decreases back below the controllers output the excess power from the controllers charge the battery.
So in your case I would recommend using both batteries until 2/3 discharged, then fire up the generator and charge them back up (boating best practices: 1/3 on the way out, 1/3 for on the way back in and 1/3 in reserve for emergencies).
But as always, it's your boat, do it however makes you happy.
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