Down here in South La. we use em for fishing the skinny water, and utility stuff.
The formula for the hp rating is length x width x 2-90, then round up. Like 16ft x 4ft wide x 2= 128-90=38. round up (I think) and that would be a 40 hp, but if its round down then its a 35hp. I currently run a 48 johnson on a similar boat thats rated for a 25, Im doing 37 on a gps with 12 gal of gas, my son, and all the fishing gear. That boat should handle a 40 easily if the transom is good. Dave A.
19x6x2=228-90=138 So its rated for a 135? Seems unlikely to me that it would be rated for an engine that big