Battery`s on bass boats go below 12.0 volts all of the time while bass fishing with fish finders, GPS units and aerators running. That is why it is necessary to have a 1000 cca battery for your cranking battery.
This is pretty much two different conversations. The voltage indicates battery charge level (and charging system effectiveness). If the battery voltage falls below 12 v, I would be very concerned.
The CCA (cold cranking amps) rating is about the plates inside the battery. How many electrons can they store? If the battery is not at full charge, you do not have a full electron load and, trust me, you don't have full rated CCA.
If I got another bass boat, which I will not do, I would have at least three big batteries. One would be dedicated to cranking the motor and nothing more. The motor would maintain its own battery. A matched pair of massive deep cycles would power the twelve volt trolling motor, and charge with shore power. If I had a boatload of electronics, I would install a fourth big battery dedicated to the electronics. The motor would charge this battery too, but I would install a spare battery charging system to isolate the dedicated motor cranking battery from the electronics drain.
Technology is your friend. Buy good stuff. Buy once, cry once.
And BTW, most batteries fail when the lead flakes falling from the plates (entirely normal) pile up on the battery bottom deep enough to short out a cell. Look for batteries with a deep waste reservoir. They last much longer.