I wouldn't go with an electric...the battery goes dead and your stuck rowing. If you just want to troll aroung in a lake a 5 hp motor will do you fine. But, if your going to go on a river I wouldn't go smaller than a 10 hp. The reason being if you go down stream depending on the current it may take you hours to go back upstream to the dock. Another thing is, it's going to depend on how many people you plan on having in the boat...if there's you and another, and you're both big guys you'll need a bigger motor to push the boat along, especially when you're going up stream. I myself had a 12 ft. fiberglass boat, it had a 5 hp motor. My Dad and I put in at Bowman Park in Albany and went down stream on the Willy. We started heading back and with the motor running at full throttle, it would only move the boat at such a slow speed we could hardly tell we were moving looking at the bank. We only had the gas tank in the motor, and we ran out of gas and had to walk back to the parkinglot and get some more gas so we cound get the boat back to the dock. It was well after dark when we got the boat back to the dock. It wasn't much fun!:think: