CONTINUOUSWAVE

I have finally finished restoring my beloved [1988 OUTRAGE 22]. It is re-powered with a new Yamaha F225F 4.2 liter model. Give me advice on propeller dimension re 17-inch or 19-inch.
Thanks.

With 225-HP on an OUTRAGE 22 the boat speed at maximum throttle should be about 47-MPH, or faster.

If you tell us the gear ratio and the recommended engine speed at full-throttle for your engine, a propeller pitch can be suggested by using a propeller calculator.

By a seat-of-the-pants approach, I would first try a three-blade stainless steel Yamaha propeller with a rated 19-pitch.

If the new engine has restrictions during initial run-in that prohibit full throttle operation, you may have to defer final propeller selection until you can run the engine at maximum to select a propeller.

Thanks Jim
Gear ratio is 1.75 and WOT is between 5000 and 6000 rpm
I currently have a 19 in testing propeller of some unknown make. It reaches 43 knots at 5300 rpm with two persons on board.
Here's a link to the engine data sheet https://www.yamaha-motor.eu/cy/en/produ ... techspecs/
Kind regards,
Davide

Fenx -

Based on owner comments, I would start with 17". Look at your engine mounting height too when making your final decision.

Using this data:

RPM = 5500
RATIO = 1.75
SLIP = 10
MPH = 47

the calculated pitch is then

PITCH = 17.5

If you want to use nautical miles per hour as the units, divide the MPH value by 1.15 to convert.

If you are already achieving 43 nautical miles per hour that is quite good; that is 49.5-MPH.

I would try a Yamaha 17 or 18". Four strokes like to get close to max rpm or else they may not break-in correctly. How high is engine mounted? Low height will kill RPMs.

Thanks so much guys
Engine is mounted 1 hole up and judging by the shape of the water spray behind the transom i would think that the engine needs to go up one more hole at least
This is confirmed by the fact that I reach top speed with a very high tilt

Engine has 36 hours already ran mostly at 3400 rpm hope I didn’t do damage to it :-((((

When it exceeds 3800 rpm the engine sound becomes much more “round” hinting that I should cruise at least at that rpm. Again this is suggesting a 17 pitch prop I guess

Cruising at the lowest RPM is usually not the best for the engine or MPG. You did not do any damage to it but I would not keep it that way. Yes, top speed is usually done a "Full Tilt Boogie" which means that throttle is mashed to the dash and trimmed until it blows out and then brought down a couple clicks till she grabs. With the right setup you should be shooting a low rooster tail at FTB.

Let me clarify....when I said the like to be run close to max rpm that is for FTB purposes. Cruising at that high RPM is not recommended.

Thanks for your valuable advice biggiefl