WTB Foot Controled Trolling Motor

I am looking for a foot controlled trolling motor for my boat. I am no expert on these, so it you think that it has enough thrust to move a 17' aluminum boat, it works for me. I was also thinking that it should be around 40" or more. Te height on my bow is something like 36". I'm not sure if that is from the waterline or from teh bottom tof the hull. Anyway, I dont think anything in the 30's will be long enough. Should I not worry about lenth. I was hopping to keep the cost under $200 and I would like to pick it up(if nearby) to save on shipping.