Prop slip factors

[esox_xtm]

OK, I'm running a '96 Evinrude 130 on a Stratos 217F w/ an OMC SST 21p and getting only 43(gps)mph. Using Ken Cook's prop slip calculator, that's like 31% slip. Is this normal for this prop OR are there other factors that I can consider, like engine mounting height? Also, I can't open the throttle all the way without over revving the engine. Am I better off to consider more pitch? I am hesitant because I like the hole shot the 21" provides. Any help is greatly appreciated, thanks!<br /><br />/mike

 

[walleyehed]

Re: Prop slip factors

At what RPM are you running, and how high will it go???

 

[esox_xtm]

Re: Prop slip factors

Sorry, spaced the RPM factor. That top speed bumps right up against 6000. Thing is, like I mentioned, I've got a bit of throttle left. How high will it go? I haven't pushed it as I don't want to damage the engine. Should I see where it takes me?<br /><br />Additionally, I have access to a SST II prop in the same size. Is that similar enough to the SST that results might be pretty much the same?<br /><br />A little more mousing around has led me to believe that I used the wrong gear ratio when figuring my slip. A ratio of 2.25 looks more like 17-19%. Not terrible, but I'm thinking I can do better. <br /><br />Just made a deal today on a 22" Raker, unfortunately I may wind up going to a 23 or 24 before I'm done...............<br /><br />Thanks for you input.............<br /><br />/mike