Re: 89 Evinrude 88 SPL rpms?
Slap, this would be a good time to consider a OMC SST stainless propeller. The SST is a cheaper alternative to a polished prop. (they are generally painted black) The older ones were telflon coated and I think the newer ones are powder coated. There are many of these props on E-bay. Type: OMC Propeller in the search window. If you buy a used one, just make sure that it is in perfect condition (no nicks or dings) and preferably has never been repaired. You should expect better overall performance and the ability to raise the engine even higher. How high is the cavitation plate above the bottom of the boat now? Does the engine mount right on the transom, and is the transon stepped out from the trailing edge of the boat bottom? Does the motor have power trim? If so how are you using it at top speed? <br /><br />In general, the further away the motor is from the trailing edge of the boat, the higher you can raise the motor, stainless props in general are more condusive to this.<br />You dont want to get carried away here as you can starve the engine for water. From what I have heard it seems like you could go one higher, if the aluminum prop begins to cavitate, the stainless at the same height probably will not. Its important to get the motor set at the proper height before you make a final determination of the correct prop, and every prop runs differently especially when you switch to stainless. A 19 pitch stainless may run 200-300 rpm higher than the aluminum, also expect to lose maybe 200 rpm with passengers. Is there a prop dealer around that will let you experiment? Just some food for thought, it seems that you are on the right path with great previous advice. If you go no further with your experiments, then a 17 pitch aluminum of the same style seems right to me.