That depends on the style of the boat. I have a 21'
SeaPro (http://www.seaproboats.net/interface.html )
which requires a 52" shaft and it barely reaches
sufficient depth.

Thanks for the warning. If the bow of the boat is too high above the
water that I cannot get any trolling motor to have a long enough shaft
for the boat, I will not be able to run the boat in electric-only
lakes. Therefore, I will need to pay close attention to this in boat
selection.

I put a Minn-Kota 70# thrust (24 v ) on mine and it
moves it quite nicely. Easy to hold position most of
the time on the first two positions with moderate
wind and will make good headway on final 3 speeds.

Thanks for the info. Seem like 60-lb to 70-lb thrust is the right kind
of trolling motor that I should look for.

The dealer mounted mine under the console along with an
on board battery charger. He then tied one to the
battery switch along with the cranking battery so
I have a backup without having a fourth battery.

Thanks for telling me the placement of batteries in your boat. This
makes sense to put the batteries in the protected area inside the
console. But if I don't have a big gas engine in my boat for the next
two years, my boat will tend to be bow heavy, and I may need to move
the batteries near the stern. Or may be not -- I may simply move big
coolers near the stern.

Jay Chan