I have a new 2012 200HO with 40 hours on a 24 foot Grady White with the hard top. The prop is the 15 1/2 by 17 pitch Rebel. The boat with full gear and 60 gal of fuel is doing 40MPH at 5000RPM at WOT. The rig gets on plane with no effort and will cruise at 30 MPH at 4000 RPM. Propped right? Or shoud I try a lower pitch or smaller dia. prop with the same pitch?
You really need to get those rpms up to the recommended 5500-5700 rpm for best results for better engine life, better fuel and oil economy, and for better performance when loaded down in rough water.
Changing the prop to a 15" Rebel may gain about 400 rpm in ideal circumstances. Possibly raising the motor one or two holes - it is trial and error - often will result in an additional 100-200 rpms.
If you have the analog tachometer, ask your dealer to go for a ride with you and to bring his laptop. The diagnostic software can compare the true engine rpm with what the tachometer reads to check its accuracy.
If the rpms are still on the low side - the 200HO is pushing a heavy 24 footer - try an SSP 15" propeller.
"There is never just one thing wrong with a boat";
-- Travis McGee, main character in a book series by John D. McDonald
The factory recommends that a properly trained technician service your Johnson or Evinrude outboard motor. Should you elect to perform repairs yourself, use caution, common sense, and observe safety procedures in the vicinity of flammable liquids, around moving parts, near high-temperature components, and working with electrical or ignition systems.
The information offered here is only general in nature and should not be construed as complete factory approved procedures, techniques, or specifications. Always use the proper service manual for your motor, up-to-date service literature, the correct tools, and have an understanding of how to proceed with troubleshooting and repair methods. If you are unsure or uncomfortable with a procedure, a situation, or a technique, enlist the services of a factory trained technician.