The thing is the 24 volt motor is more powerful so you spend less time to travel a given distance. So your not on the pedal as much,or your using a lower speed than the less powerful motor. So all things considered the actual power consumed in amp hours probably works out to about the same. If you ran some really definitive test it may be under certain conditions the 12 volt motor on two batteries may have a little longer life or vice versus. It takes so much THRUST to do what you need to do regardless of voltage. I have a dual voltage trolling motor on one of my boats you can switch from 12 to 24 volt. And then you have 5 speeds on each voltage. If I put it on speed 5 on 12 volt I go slower than on speed 5 on 24 volt. So traveling a given distance I am using about the same amp hours I am estimating.

Can you get by with a 55 lb...yes. Will there be times you wish you had the bigger motor...yes.

To me it's all about how tight your budget is or how much spending the extra money will bother you. If it's not a strain or your not going to have buyers remorse about spending the extra money I would definitely buy the bigger.

No matter what we have we generally find a way to adapt our fishing to work. If I did not try to fish in the wind holding position I could always use a troller 40 percent or more smaller.

Now this longline trolling and pulling cranks and stuff...thats a different thing. More thought required on exactly how many hours you need a given thrust for.

Boy that was long wasn't it. Oh well I wasn't doing anything else . I never thought I would type this much. Heck I never thought I would type at all in my life. I took typing in High School just to be around the girls. I kinda only speedy hunt and peck though.