I have the 15' SC Alaskan split seat,with a Yamaha 25hp oil injected motor. I would go with the 25 over the 15. My boat runs almost 35 mph with me, an 85 lb Lab, battery,and full tank of fuel. My friend paced me along the dam at potholes,in his truck. I can run for 2-3 days on a tank of gas, but the 4 stroke will run longer. My 25 will troll slow enough to fish in the lakes but I use an electric motor to troll anyways. The only thing I dont like about the 25 is the bow comes up pretty high when getting on the gas but I get on plane in about 3 sec,so it's no big deal. Either way you go I'm sure you'll be happy, I love my combo, I have lots of time on the sound and the big lakes in E Wa. and have never felt unsafe on any water within reason.