Thanks to the efforts of Dave King - Pygmalion received the DLK hull fairing and a used 17" Max Prop in December. 

Below are motoring only performance figures before and after the fairing. 

Speed tests are averages between a course to the west then a reversed course to the east in the Alameda Estuary - winds very low in both cases.

Speed is in knots - Beta 1505 38 HP with 1:2.5 transmission.

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Looking at the results the Max Throttle at 2500 rpm indicates an over pitched prop.  Fixing the pitch will have to wait until the next haul out in a few years.  

I also noticed that the "prop" noise seemed louder then the 3 blade fixed.  

I suspect that the new 17" prop (verses 16" fixed prop) plus fairing resulted with the blade tips being close to the hull and is a cause of increased blade noise.  

I also suspect that the blade design for the Max prop is noisier then fixed blade - comments from others who have switched? 

Jay Bietz wrote:

Thanks to the efforts of Dave King - Pygmalion received the DLK hull fairing and a used 17" Max Prop in December. 

Below are motoring only performance figures before and after the fairing. 

Speed tests are averages between a course to the west then a reversed course to the east in the Alameda Estuary - winds very low in both cases.

Speed is in knots - Beta 1505 38 HP with 1:2.5 transmission.

11/15/14 Before Fairing 16 x 16 fixed	RPM	KMeter	GPS SOG
Off Idle	1000	2.75	3.15
	1500	4.25	4.75
Cruising	2000	5.25	5.70
Max Throttle	2750	6.30	6.75
1/10/15 After Fairing 17" Maxprop 24 deg pitch
Off Idle	1000	3.60	3.55
	1500	5.10	4.85
Cruising	2000	6.00	5.95
Max Throttle	2500	6.75	6.55
Wide Open Throttle - Neutral	3200

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Looking at the results the Max Throttle at 2500 rpm indicates an over pitched prop.  Fixing the pitch will have to wait until the next haul out in a few years.  

I also noticed that the "prop" noise seemed louder then the 3 blade fixed.  

I suspect that the new 17" prop (verses 16" fixed prop) plus fairing resulted with the blade tips being close to the hull and is a cause of increased blade noise.  

I also suspect that the blade design for the Max prop is noisier then fixed blade - comments from others who have switched? 

You need to reduce the pitch on the prop.  Dividing the in-gear RPM by the out-of-gear RPM, you get 78%.  You had 86% with the fixed prop, which is more in the 85% to 90% range, where it should be.  You should reduce the pitch on the Maxprop to the 22 degree setting, and that should be about right.

I thought the hull fairing was for sailing performance

The max prop is definitely noisier than a fixed prop. I sail and care not

Jay, we didn’t do the analysis you did but think the results are similar.  Last year we had to motor form San Francisco to San Diego as there wasn’t a breath of air the entire month. This gave us a lot of motor time to ponder and both of us concluded that our motoring was about 150 RPM less to maintain the same motor speed. No wind was a real bummer as we did the fairing so we could sail a lot more on our next trip to Mexico, notorious for light winds.

As for sailing, the first time we sailed after the fairing was across San Francisco in front of the Golden Gate.  True wind was 4.5 Knts on a broad reach and Worldwind was doing a steady 4.1 knts on the GPS and knot meter at slack tide.  We had a Kern super Yankee, staysail and full batten Kern Mainsail up.  We both were amazed with the improvement the fairing made. Normally we would have had a drifter up. We sailed to San Leandro for the WS rendezvous in conditions I would normally have motored in.  Duke on Amable was along with us, having the same results.

Your Max prop will sound different as any change in the prop would. If you call PSE they can tell you exactly what it should be set at. I added a drive saver when we had a fixed prop, relocating it an inch back and it sounded different.  When we first put our Max prop on we thought we had set it to high as the motor seemed to run a little warmer. I called PSE and they said I was actually set to low.  We changed it and the difference was more than noticeable.  Lastly the Max Prop is supposedly just a tiny bit less efficient than a good fixed prop, but we couldn’t tell.

Jim

Most of your noise is coming from the tip clearance.  I wish I still remembered the formula, but I can tell that you're to close even though it won't cause any harm. Our photo doesn't show the clearance real well but I think you can tell it's more than yours and I remember it still wasn't what it should have been. I had cut the hull and rudder both quit a bit to get as much clearance as possible. This was done ten years before the fairing.

Jim