[lecomte38]

Dennis
I have no idea what the universal trans ratio is. I used the Yanmar/Kanzaki ratio of 2.6 to 1 for the calc. Most mfgrs aim for about 1000rpm at the prop shaft.
The prop slip/efficiency comes into play a lot more as the boat approaches hull speed. I am slipping/loosing 18% at 1500rpm and 45% at 3000 rpm.