My father used to have a 14' Transom canoe from Sportspal, he used a trolling motor with a marine battery and he had a charger in the house.

It worked out great, we used to row out past the weeds and then motor over to where the fish were.

We used to get a good hour or so of run time on a fresh charge.

He used to put the battery on the charger's slow charge setting when he got back from fishing.

I think that the difference in the batteries is that car batteries are pretty much useless if you discharge them more then 40%, where the marine battery can be almost fully discharged and still recharge.