@SonsOfPerchin... I have a MotorGuide Xi3 24 volt 70 lb. thrust that will push my 16.7 ft. Sylvan 3 mph at full power on flat water. I doubt if it would run for more than a couple of hours at full tilt though and I use 2 large group 31 Interstate batteries. Spot lock works perfectly holding me on spot even in wavy conditions and have not used my anchor in years. I use it mostly for steering when trolling. When the water is fairly flat it will last about 8 hours at 1/3 power when used solely for steering along with the main motor doing the trolling But that time gets cut in half in 2 foot waves when I need 2/3 to 3/4 power to maintain steering control. I don't think that even a 36 volt motor will run anywhere near as long as you were hoping for at 3 mph pushing the boat by itself. Lithium batteries will power for longer periods than flooded lead-acid but is it enough to justify their exorbitant price tag and special charger that's needed?
Thanks and your right. The more I look at smaller gas tiller motors the more I am leaning that way. Truthfully it was the ipilot and spotlock that had me wanting one but I guess money I save from not going electric could go towards a new fishfinder lol