optimax 115 cant get on plane with load

[David Andrew]

Hello i have a 06 optimax 115 bought it refurbished last year I am a commercial salmon fisherman on the lower yukon river. this year the outboard has trouble getting on step with 1000 lbs or more the engine runs smooth and doesnt seem to be misfiring or anything. I am using a 17p prop for load and a 21 without load. I got a couple of buddies that has the same outboard and they dont ever have the problem i am having.without a load it is a little slow to reach full power i get about 5100ish revs without a load. I also just raised it up a notch and the anticavatational plate is out of the water but since then i lost speed any ideas or fixes?

 

[SkiDad]

have you verified spark on all cylinders ? if everything is running fine you might want to drop down to a 15p prop when you are carrying heavy load.