At full throttle, and a clean bottom, I motor at 8.1 knots at 3100 RPM.
My normal "around the harbor" cruising speed is 6 knots at 2000-2100 RPM
Once you go away from a fixed prop, it is my overall opinion is that the relative differences between the various prop options is so small in normal operation you'll never notice, so if I had to pick a new prop, I would pick the cheapest one that I felt was robust and well designed, and minimized maintenance. If my passion was racing, I might be paying a premium for low drag, if I was on a motorsailor and put 1000 hours a year on my engine I might pay extra for improved motoring performance, but neither of those are on my valued added radar.
Only once have I ever feel like the boat could have used more power. Coming out of the southern end of the Cape Cod Canal, with a following tide, into the te
eth of the afternoon southeasterlies. (All the New England sailors on the forum are smiling knowingly about now...)
The 25 knot winds driving straight into the south tidal current had kicked up miles of the shortest, steepest chop I have ever had the misfortune to have to motor into. And motor was the only choice, the narrow channel was straight into the wind. We made progress, but it was slow and very uncomfortable. As a small consolation, we were making slightly better time than the other boats around us.
Once we got to deeper water where we could bear off and sail without the engine our VMG went way up, and we were a lot more comfortable--and we left those other boats, still motoring, further behind on each tack.
Sound Harbour, Eleuthera, Bahamas
, wrote :
Bill, I was going to buy a Autoprop from Alexandre , when Olivier informed me that the boats were modified to fit the Autoprop. I would be interested in the performance , eg. cruising speed /rpm ,max speed/rpm and appreciate your overall assessment of the Max prop on a SM.,particularly as you have the same engine I do.