Thanks for your experience. I'd like to keep discussion open for more advise on these and other models.
Autoprop - always been curious about this prop. Can you advise your experience with fwd/reverse prop walk and if you found the blades move and noisey under sail. As well, any trouble with blades not opening under fwd/rev. And as above your sales & service experience, how was it ?
Very little prop walk, the efficiency is the same, backwards or forward, you don't hear nothing and no problem at all. I had never need any exterior service. the maintenance is very simple and I have done it myself (5 minutes).
This is not just a folding propeller, but an automatically adjustable pinch propeller. Itīs biggest advantage it's the cut on fuel consumption and the increased autonomy.
It is especially efficient while motorsailing. Suppose I have wind to make 3.5 knots and I want to make 6 knots. With the standard propeller I would have to put the motor at 2000rpm. With an Autoprop, to do the same, I only need 1000rpm. There is almost no noise and the autonomy increases almost twice, not to mention costs and motor life. The only problem is that when the wind picks up and you donít need that extra push to sail at more than 6K, sometimes you forget to turn the engine of, because you cannot hear it.
It is also very efficient if you have flat seas, or just small waves. In those conditions I could make the same speed with less 800rpm, comparing with the standard propeller.
In stormy or very agitated seas probably this propeller is marginaly less efficient than the standard one. On those rare conditions were the speed of the boat varies constantly because big waves are stooping the boat I believe that there is some loss in efficiency (because the pinch is changing all the time), but I am not sure.
The other only propeller I would consider to replace an Autoprop would be a Gori with and overdrive. They were also impressive on that test that I had mentioned.