Electric motor sizing

I know this topic has been sort of touched on, I've read and seen pics of the motor/battery mount and what not after running a search, but....

For those who have a motor on their boat is there an optimum size? Is "the smaller the better" the rule? Powered cruising is not my goal. I priced trolling motors and new, the prices are not bad but there is quite a range of power ratings.


Jeff.

I'm just back from 3 days on my H-16 camping down & back on the Columbia river. My homebrew electric drive saved my butt, but I'm ready for more batteries: I use the cheap readily available communications gel cells (sealed, safe, dependable) 12V 12AH. 2 in parallel down in one hull in a secure container wired through a watertight gland along to the dolphin striker mounted old tiny electric trolling motor mounted on an aluminum swivel I fabbed up. Pull a cord on the tramp through a block with cleat to lower or raise, pin in place if you're gonna' need reverse. I removed the speed control resistor and steering head to save weight and electric drain (if I need the motor I'll take all the speed I can get out of the batteries instead of wasting it to make heat in a resistor). Steering is via the cat rudders and the control for the motor is a cord with a waterproof DPDT switch so I can sit back and relax. 2 cells got me 30 minutes against the current. If I were rich I buy some Lithium Iron (yes Iron) Nanophosphate cells and plaster the hulls with flexible solar panels and go for hours or days...my other lifesavers: 2 6" thinwall PVC pipe storage tubes with rubber Fernco caps on the ends and surplus long narrow Thermarest stuff sacks to store all the gear lashed under the tramp, and beach wheel cradles on the fwd pylons to carry the CatTrax (come-along in one hull, throw bag anchor line / winch line clipped to the striker) to get the boat above tide and wake line each night...