A 16' 51" boat is the bare minimumI would use with 3 people. And a 40hp would also be a min. too. I have worked in and been around the marine business for 25 years.Two guys can do 12-14' but 3 is asking for trouble. The problem you'll have is the weight you add. 3 grown men with waders, bags of decoys, guns and shells, possibly adog. You're talking close to a 1000lbs or more. If you have a narrow boat, it'll cut itself down through the water and submarine. Seen this with a 14' with 2 divers 1 boat operator and a nav/dive asst. As soon as they tried to power away boat just went down.