Choosing batteries

Why run dual purpose over a starting battery? 03 tracker with 50hp, two graphs, live well and lights. Just ordered a 12v terrova and want to upgrade batteries. Thinking either 27-31 deep cycle for trolling. What should I get for starting and accessories? Dual purpose or cranking and why

Dual purpose are for exactly what you want, both cranking and running some lower current accessories. Deep cycle batteries have lower cranking amp outputs, and cranking batteries will not last when continually discharged and recharged.

I have a regular starting battery for the outboard, one graph, and pumps. I don't usually fish for longer than an afternoon so it doesn't get discharged all that much between runs. If you were taking multi-day trips, or had more accessories, you'd want the dual purpose or even another dedicated electronics battery.

You want the biggest battery you can fit for the trolling motor. Everstart 29DC from Walmart is a good choice.