I use a 6 hp long shaft Johnson motor on my drift boat alot to fish the Sound and some rivers. What I have found is that weight is not your friend. Horse power is not important with a max hull speed of maybe 8kts tops. On the 17' you're probably looking long shaft too. Even though you can go small and light, you definately don't want a self contained gas tank type of motor. That puts you up in the weight class again. By the way, you are going to want to get the tank as far forward as possible (under front seat?) for weight distribution (a good distance on a 17'). 4 strokes are nice, but even the newer 2 strokes are on the heavy side for me. I really don't know what to recommend since I'm not all that happy with mine. Best I had was an ancient (and lighter) 6hp "Fisherman". For lakes the bigger electrics are intrigueing and I've wondered how they would do as a kicker on some rivers. Hope this helps somehow. I'm interested in what recommendations this thread brings. Dang motors are a HUGE investment.