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Hello Rick,

We put the 18" Autostream on our 1990 boat about 3 years ago after running the stock fixed prop for about 2 years. My expereince with boats speed was about the same as yours. I had set the prop according to Autostream's commendations of 19° forward and 14° reverse but the engine wrapped up to full speed and didn't seem to be putting much power into the prop. I spent a couple of hours in scuba gear one afternoon and did a trial and error pitch adjustment. I did a series of tests where I increased the pitch a little then did a full-throttle run. I had to add about 5°-7° to get into an over-pitched condition where the engine wouldn't achieve the full 3600 rpm at full throttle. Then I backed it off a couple of degrees. Once I did that I was able to get as much speed with the Autostream as with the fixed.

I don't recall what I ended up with for pitch. I set that up on the bench before installing it and found a single turn of the adjusting screw added 2.6° degrees. (hey, it was winter, I was bored and have a shop full of tools) The 19° wasn't enough so I made the in the water adjustments described above.

A couple of points:

The reverse pitch is independently adjustable. I left it at 14°. Lower pitch is the reason you have less prop walk. I find we have almost no prop walk in reverse.

I think you are right about the feathering props not being as efficient as fixed pitch. The blade shape is a compromise without any twist for best feathering performance. We no burn more fuel for the same trip up or down the Columbia River with the Autostream by maybe 20%. Since we only use about 50-75 gallons most years this isn't an issue.

The Autostream doesn't run as smooth as the stock prop. There is a little more vibration.

If we ever take a long trip north up the Inland Passage (B.C and Alaska) I might put the fixed prop back on since that's an area with lots of motoring and little sailing.

All in all I am satisfied with the Autostream. I chose it because it was several hundred less than either the adjustable pitch MaxProp and Autoprop. Maybe the MaxProp would be more efficient under power because it has more blade area, I don't know. I know people with all 3 types and all are happy with them. Autoprop probably gets the motoring and motorsailing award for overall efficiency. On a trip from Astoria to Barkley Sound (Vanc. Island) last summer we buddy-boated with Bob and Rick Teeter on Camelot which is a sistership - same year and all. It was strictly motoring all the way north and they burned about 32 gallons of fuel to our 40.