How common is this? <br /><br />My 15.25 X 17 Powertech OFS stainless prop produces the following numbers on a 19 foot Boston Whaler Nantucket with a Honda BF135 motor mounted 2 holes up:<br /><br />RPM SPEED SLIP %<br />4000 31 mph -3<br />5000 38 mph -1<br />6000 45.4 mph -.5<br />6300(wot) 46.7 mph +1.5<br /><br />I called Powertech yesterday and a technician told me that the prop privides good lift and when mounted high, the cupped tips in effect add more pitch to the prop. Is this true? I think the prop may be mis-stamped and be a 18 pitch prop. This 17 pitch prop would produce single digit slip numbers for an 18 pitch prop.