21' stx cuddy lookin to optimize the prop

[ERICR]

I have a 21' searay cuddy with a 305 and it really seems like it has a hard time plaining its a 14.75 by 17 pitch prop with a 1;50 or a 1;47 outdrive it just doesnt seem like it wants to plain well iot does but its toward the enc of the throttle

 

[KC WV]

I've got a '97 215 with the 5.7L Mercruiser with 1.62:1 ratio and run a 14.25 x 19 4 blade prop. Planes after i get to about 2800 rpm. My Dad's boat is a '86 210 cuddy with a 4.3L with 1.84:1 and he runs a 14 x 21 3 blade and planes at about the same rpm. Are you sure the outdrive is going all the way down? If not, it may have air in the hydraulic system and needs bled. Is the engine running at the correct RPM's? Could need a tune up.