Selecting Propper Propeller

[waterbill]

I bought a used 17' deep vee skiff with a '96 90hp Yamaha and a 13x19 SS prop. The seller told me he runs it up to 4200 rpm to plane and then backs down to 3900 to stay on plane and conserve fuel. The boat seems to work just fine this way for me, but I understand that to not operate the engine in the recommended rpm range spells trouble for the engine. Now I wonder if I have the right prop for this. Does anyone out there know what the correct WOT rpm is for this engine? Does it sound like I'm out of specs?

 

[Hooty]

Re: Selecting Propper Propeller

My guess would 55-6000rpm.<br /><br />c/6<br /><br />Hooty

 

[steelespike]

Re: Selecting Propper Propeller

If 4,200 is the max it will do then it is probably running below the recomended wot rpm. If it does reach its recomended range then it is fine to back off and run at a comfortable cruising speed.

 

[Jack Shellac]

Re: Selecting Propper Propeller

4200 RPM is too low for this engine. Just as a reference, I have a similar setup to yours and a 15"p prop turns at 5600 RPM. A 17"p turns at 5100 RPM. Both are stainless steel.