So I have decided that I need a fishfinder to go on my kayak.
The problem is this: I have no clue how the battery thing works. I know that there are portable models, but I am looking at a few that I like that are not the portable models

(specifically the Humminbird 561 DI) So if I were to get a model that does not say portable, could I some how rig up a battery system in my kayak

(I was informed that portable models had there own battery pack.)
I will also add that I want the for finding structure (Puget Sound Lingcod/Rockfish [if it ever opens again]).
Any helps appreciated
