Hayden, it's an Autoprop, and Autoprop has no stops, the blades are free to rotate 360 degrees.
An Autoprop has a proper shaped blade profile, an airfoil, is is not a flat plate like most if not all other feathering props. It has a couple or three clams to fame, first it is more efficient as it blades have a proper shape.
Secondly, it self pitches based on load, it really shines in motorsailing, give me 6 to 7 kts of wind on the beam and the engine at a high idle 1000 RPM , and i'm motorsailing at right at 7 kts, or wind speed, but tow another boat for example and engine load remains the same, but you slow down of course, add sails and engine load remains the same, but you speed up, it's essentially an automatic transmission.
Thirdly, any properly shaped blade will produce terrible thrust in reverse as its leading and trailing edge swap, and then it becomes a very inefficient blade. Props like Max props etc appear to have a strong reverse mostly because they have no blade shape, however the Autoprop when placed in reverse, the blades flip around 180 degrees and the leading edge is still the leading edge, so thrust is the same backwards or forwards, however gearbox reduction ratio may have the blade turning slower in reverse than forward.
The Autoprop was actually designed for use as a landing craft prop by the British in WWII, they had a need for a propeller that had just as much thrust in reverse as it did in forward, cause if your under fire, you have a strong desire to get off of the beach I'm sure, being stuck aground may be fatal.
I guesstimate that the Autoprop's blades are driven towards flat pitch by centripetal force, and if it were not for the aerodynamic shape to the blade it would provide no thrust to a stationary boat, when your not moving an Autoprop provides very little thrust, it takes some RPM to actually get moving in a normal manner, however when the boat begins to move, I believe the induced flow drives the blades to higher pitch, its sort of a faster you go, the faster you go thing, until of course the forces balance.
I think my problem is, and in my case if I'm right its not solveable by any means I'm willing to undertake is that my old boat has a really wide keel, much more so than newer IP's, and this excessive dead wood has a large amount of the props swept area in turbulent flow with little to any induced flow, since blade pitch is driven by induced flow, the blades are changing or trying to change pitch a couple of times each revolution and this causes vibration.
Pity too as the prop is so efficient, I hate to get rid of it, I'm a heavily loaded cruising boat, with a generator, 1 kw Solar, large batter bank etc. I had to raise the water line a couple of inches, yet with the Autoprop she motors at 6.5 kts at 2,000 RPM and burns 1 gallon an hour. Vibrations start above 2,000 though and don't stop until 3,000. I think that centripetal forces overcome induced flow at that speed.
Link to show how the Autoprop works