The Autoprop is an automatically self-pitching feathering propeller that maintains maximum efficiency at all times. It has a higher efficiency over a wider range of RPM settings, producing higher speeds with lower engine RPMs.
Automatic Self Pitching: Self pitching action enables less rpm to be used to produce comparable or better thrust & boat speed.
- Faster boat speed with less rpm
- The boats range under power alone is increased… up to 30% fuel savings
- Engine runs quieter, at lower rpm, with less vibration and wear
- Enhanced performance in rough seas (the engine does not overload), with more thrust to punch through the waves.
Same Blade Shape in Reverse: Blades swing thru 180 degrees in to reverse, presenting the same propeller shape and leading edge as in forward.
- Handling is more predictable and stopping power is dramatically improved
- Prop-walk in reverse is eliminated in most every case
- Cavitation is eliminated
Low Drag: Blades align themselves to the water flow when under sail.
- Sailing drag is reduced by up to 85% when compared to a 3-bladed fixed propeller of the same diameter and blade area
- Feathering to the water flow rather than the shaft angle also reduces drag still further on steeply angled shaft installation.
Benefits of Autoprop Propellers
- The only fully automatic self-pitching propeller available.
- The Autoprop had a maximum efficiency of 70% … Higher than all other props tested – Fixed, Folding or Feathering.
- Blades are true profiles (aerofoil), not flat (planar) blades like all other feathering propellers. Therefore greater thrust is developed in both forward and reverse at all engine rpms.
- In reverse, a true blade profile is in effect. No cavitation, greater stopping power and control, improved handling, almost no prop walk.
Unique Autoprop Features
The feathered image above shows how, when sailing, Autoprop reduces drag by up to 85% compared with a three blade fixed propeller; with the two blade propeller the reduction can be even greater. This drag reduction can equate to as much as one additional knot in sailing speed.
Autoprop automatically varies its pitch depending on the conditions. Put simply, as the wind or sea conditions vary so does the blade pitch. The result is maximum efficiency whatever the conditions, with increased speeds at lower engine revs and lower fuel consumption and emissions.
In reverse the Autoprop blades swing through 180 degrees and present exactly the same blade shape as they do ahead. The result, the same excellent thrust, with greater stopping power and less prop walk.
The AUTOPROP has performed wonderfully. Hirta is a knot faster under power at economical cruising rpms, and that’s only a bonus. Our original intention was to alleviate the drag put on her by a 19-inch 3-bladed prop that had dogged her under sail for years. That effort was completely successful. Her speed has been transformed so that she is sailing as she was originally intended for the first time since an auxiliary engine was installed in 1930. We are now sustaining speeds for long periods which previously were only touched briefly on the surge, and Hirta sings for joy now that she has been relieved of her heavy burden! This has been achieved with no shaft vibration whatsoever. In 13 years of owning Hirta, nothing we have done has had so dramatic an effect on her.
I cannot tell you how pleased I am with the performance of my new AUTOPROP. I have gone the entire route, from three-blade fixed to three-blade feathering and then to the AUTOPROP. With all the other props my two problems were motoring into a head sea and reversing. My boat is heavy with full sections forward and a lot of freeboard. When motoring into a head sea and wind, the best speed I could achieve was around 4 knots. With my Autoprop I can now motor into any weather at 6 knots. When reversing, my boat always went in a circle to the left. I could never get enough way-on to get steerage, and reversing off a lee dock was a nightmare. With my Autoprop I have steerage immediately, and it makes me look quite skilled. With my other propellers my speed was 6.2 knots, with my AUTOPROP it is 7.2, an increase of nearly 20%.
Putting aside the benefits gained like decreased vibration, less noise, and decreased weight, the Autoprop alone is responsible for nearly a 50 percent increase in range. It is hard to imagine a more dramatic improvement, 3-blade vs. 3-blade. I’m impressed at the speeds achievable with the Autoprop, and even more amazed at the RPMs that achieved these increases. I am now able to drive the boat to hull speed at a lower rpm under any sea conditions.
My wife and I have cruised over 1400 miles during the season, and I am pleased to say that our new AUTOPROP has lived up fully to our expectations. For starters, we have experienced an increase in speed of an average .75 knots. In lighter airs, again, there has been a distinct improvement, not only in pointing higher to the wind, but in the improved performance through the water putting us well on par with some of the lighter displacement cruisers, where in the past we have been left well behind. Take-up to full power is much faster and smoother. Maximum speed of 6.5 knots is achieved quickly. We find a considerable improvement in reverse speed, power and stopping in forward motion. We have also obtained a significant decrease in fuel consumption while under power. Overall, our cruising has been outstanding, largely due to the installation of our Autoprop.
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