well, the larger you have the heavier it is and also pull more on your battery.i have a 52 lb thrust motor on my 16 ft flatbottom for fishing.most days its plenty and some days i wish i had a 152 lb thrust motor.i would say for your application, 40 or so pound thrust motor should be sufficient.check your local boat dealer for people that trade theirs in to upgrade to a larger motor and of course the large outdoor stores usually run deals from time to time.keep in mind it has been several years since i have been motor shopping and i am not the best to give advise on this.this has been my limited experience though.