Duel purpose battery

For cranking and everything but the t-motor yea or nay?...it's time for a cranking battery....I spoke with an interstate rep who said there deepcycle batteries are duel purpose and will work for cranking as well....that was sorta confusing.

I run a dual purpose battery in my boat. It is an Optima blue top. It powers live wells, aerators, oxygenators, bilge pumps, 3 sonar/gps units, accessory and box lights, and cranks a 250 Verado Pro.

I use nothing but Cabellas AGm batteries. 1 for cranking and everything and 2 for trolling motor. Generally last 5 years.
Johnny

I've used just deep cycle batteries in the past and never had an issue with cranking and everything else. I just made sure that it had the cranking amps that I needed. I only have a cranking battery now because it was already on the boat.