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evinrude 15 and 1236 how to get a lil more mph?
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<blockquote data-quote="Johny25" data-source="post: 327817" data-attributes="member: 7791"><p>Ok well here is what your numbers come out as....</p><p></p><p> You have a 9 pitch prop being spun by a 2.41:1 gear case at 6,550 rpm at 22.5mph which comes out to a 3% slip ratio. Now I have never seen a little motor like this have less than 10% slip ratio, fact is 3% slip ratio is better than anything I have ever seen on any motor and setup....including racing boats. If you understand prop slip then you know 0% slip is impossible because the prop is not traveling through solid matter. </p><p></p><p> I do not believe you are lying about GPS and I can see your tach reading so my only other guess would be the prop is mis-stamped and it is really a 10 pitch. This would calculate to a 13% slip which is what is expected to see on this motor and setup, and 13% is a very good number at that for this setup. </p><p></p><p> On a final note, you could go up another inch in pitch and get another mph or so out of her if you wanted. I would wanted the motor turning 6250-6500rpm tops</p></blockquote><p></p>
[QUOTE="Johny25, post: 327817, member: 7791"] Ok well here is what your numbers come out as.... You have a 9 pitch prop being spun by a 2.41:1 gear case at 6,550 rpm at 22.5mph which comes out to a 3% slip ratio. Now I have never seen a little motor like this have less than 10% slip ratio, fact is 3% slip ratio is better than anything I have ever seen on any motor and setup....including racing boats. If you understand prop slip then you know 0% slip is impossible because the prop is not traveling through solid matter. I do not believe you are lying about GPS and I can see your tach reading so my only other guess would be the prop is mis-stamped and it is really a 10 pitch. This would calculate to a 13% slip which is what is expected to see on this motor and setup, and 13% is a very good number at that for this setup. On a final note, you could go up another inch in pitch and get another mph or so out of her if you wanted. I would wanted the motor turning 6250-6500rpm tops [/QUOTE]
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evinrude 15 and 1236 how to get a lil more mph?
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