speed problem

[JD Livingston]

I have a 1997 Javlin bass boat 389 sdc 181/2 feet long. Its got an evinrude 175 and at the fastest it will go is 50 miles an hour any one have any ideas its turning 5000 rpms

 

[john@marineengine]

the rpms should be somewhere in between 5250 to 5750 it sounds like a prop issue

 

[JD Livingston]

the prop is a 23 pitch raker.

 

[JD Livingston]

should I try moving the engine up ? its sitting on an 8 inch plate and the cavitation plate level with keel