I would suggest at least 24 ah of battery. If you plan on fishing more than a 10 Hr day or a second day without being able to recharge you'll need even more.
You can run one big battery or multiple batteries in parallel.
If you plan on doing a lot of fishing I would also recommend getting a lithium ion battery. They are A LOT MORE $$ upfront but will out perform a lead acid-Gel, or AGM and in the long run cost will balance out. LI batts are about 1/3 the weight of lead acid also.
I've never been good, But I've been Lucky!
I don't Lie or Exaggerate, but sometimes I remember BIG!