Depends
You need a regulator if the output of the panel is greater than 1 1/2% of the amp hour capacity of the battery bank to which it is connected.Not clear how your boat is set up. You wrote: "the two (2)Battery bank." Singular on bank, confusing, most likely two batteries with a 1-2-B switch.You could wire the positive output of the panel to the C post on the switch, but the downside is you'd have to leave your switch on both when you leave the boat and the higher powered battery would discharge into the lower one.You may have to just bite the bullet and chose one of the batteries and connect the panel to that one. That's what I'd recommend with your relatively small charger, since even if you have Group 27 batteries in each bank, you could hook it up to one bank. Also be careful about voltage. If you have wet cells you're OK, but gel cells will need the regulator regardless of size of banks, because gels need to be limited to 14.1 volts or else th batteries will fry.Others may have different ideas about how to hook the two up without having the switch ON without the complications of combiners or echo chargers.