-- Last Updated: Jan-20-13 1:20 AM EST --
...... my best advise to you is get a Minnkota with "Digital Mazimizer" . This type motor also has a variable speed control grip on the tiller .
Minnkota now has the old standby Endura with Digital Maximizer ... it is called the Endura Max .
45 lb. is sufficient , though it looks like the Endura Max can be had in 40 lb. also ... I would choose the Traxxis model myself but the Endura Max should be about the same now that it comes w/Maximizer .
Believe me , "Digital Maximizer" is that big of a deal ... it makes all the difference in how much time your battery can run the motor before it starts to get weak and poop out .
You really want go go time and distance capability ... get a 130 or 145 amp hour deep cycle for your main batt. , and for the spare (secondary backup) perhaps a smaller 110 ah .
You can customize the shaft length on most stern mount motors to whatever you wish (shorter that is) , it's not difficult , and if you aren't comfortable doing it yourself ... there's usually a Minnkota service center nearby who will do it for you . 36" is OK to start with , if you think it's too high at the grip and head after using it awhile ... then consider shortening it a few inches or more .
Just a side note , these transom type motors can also be used up front to pull the canoe instead of push it ... which I think is much more effecient . Try it both ways and see what you think !!
Check out the Traxxis and the Endura Max in the Freshwater Transom-Mount motors ... make sure the model you are looking at says it has Digital Maximizer and is "variable speed" (not 5 speed)
http://www.minnkotamotors.com/products/trolling_motors.aspx?subcat=4
Don't forget , you're going to need a decent charger as well . Don't even consider a charger that has less than 10 amps per bank , 10 amps is important & recommended ... reason for that is it has the juice to get the batt. up to heat quickly which is important in maintaining the batt. and getting long service life out of it ... a 5 amp charger won't cut it .
Minnkota sells an MK110 which is a one bank (charges 1 , 12v batt. at a time) 10 amp. 3 stage charger ... it's in that link as well somewhere .
You also may want to consider a nice little gas powered engine 2.5 - 3 hp. ... faster , more power , less weight , less number of components in the system , less complicated to deal with ... mount it on , pull the cord and off ya go at a surprising clip , a small can of gas last a long time (some lakes won't allow gas engines though) .
In either case , most states req. registering a canoe that is powered by electric or gas , check your states boating regs. on that .
Tip ... take the motor or engine out of the vertical lock position when running peidmont/mountain rivers or shallows ... so it can kick up if the pod strikes an underwater obstruction ... instead of hanging and causing a nasty spin , even a capsize !!