Max prop

[Mike]

I am considering installing a 3 blade max prop in replacement of my 2 blade feathering prop on my 36s7. Does anyone have any experience with the max prop or any of the other feathering props ex. martec or autoprop? I am concerned that the 3 blade will still cause significant drag.

 

[Jose Venegas]

If drag is your concern, go folding

Feathering props have usually more drag than folding props. Also, some feathering props like the Max Prop or the Auto prop, have flat blades that make them less efficient during motoring. The draw back with the folding props is the need for centrifugal force to open up and such a force is small when they are folded (Force~mass*RPM*radious^2). . As a result, it may take to rev up the engine to open them and then you get a big slam on the shaft. Also, they are not very good in reverse as the leading edge of the blade becomes the trailing edge in reverse.I personally went Gori 3 blades to replace the 2-blade fix that came with my 361. It folds nicely, it has twist in the blades and it uses the force of the water to start opening up and it does not slam the shaft. Also, it has a clever mechanism to flip the leading edge in reverse, giving it a good grab in reverse. I tested it yesterday for the first time and it worked like a charm both sailing and motoring. Very smooth ride and excellent reverse during docking. Last, but not least, it is easy to service and it cost less than a MaxProp.The web site below has all kind of prop links.Good luck Mike

 

[Jose Venegas]

Sorry, the Autoprop does have a twist

I meant the Martec Auto steam and not the Auto Prop. The Autoprop does have twist in its blades and is claimed to have better efficiency than all other props including fix props. The problmes I saw with Autoprop were its cost, the complex and delicate set of bearings in its mechanism, and the fact that all three blades adjust their pitch independently. Thus, a little barnicle in one of them can cause a good amount of vibration.

 

[John W]

Folding Props Decisions

Mike;I went throug a great deal of research before deciding on fitting a 2 blade Flex o Fold prop to my Beneteau 361., equipped with a Westebeke 3cly 27hp engine.The prop drag was reduced but a by product was severe vibration. Further research seemed to indicated that the vibration stemmed from a combination of boat design (very wide and flat after beam) and the Westebeke 3cy engine. I told the local prop dealer of the vibration, and my concern; then to my surprise and delight the Flex O Fold people came back with a three blade folding prop which I consider the very best of customer service. The new 3 blade Flex O Fold is smoother than the original fixed 3 blade resulting in higher speed at lower RPM under power. Drag is notably reduced from the fixed prop and I do not think it offers much more than the two blade folder. The great thing about the Flex o Fold is however their superb customer service. John.