Weight distribution, engine
trim and outboard
shaft length can all be a factor.
Weight distribution - more weight forward? Anyway, play around with it.
trim - trimming the shaft as close to the stern as possible may help to get on the plane.
Shaft length - the anti cavitation plates of the shaft should be pretty much on the same level as the underside of the hull
in that area. If anything, the anti cavitation plates might even be a bit higher, say an inch, than the underside of the hull
in that area.
If the above does not help, looking into the prop might.