MAX Prop equivalency??

Hello all you prop geniusies! I could not get a straight answer from PYI so I will try here. Question: Im replacing a standard Michigan 3 blade cruising17 D X 14P prop size. with a MAX Prop of same size and pitch. 3 Blade Classic 17DX 14P. Now which has more thrust at same RPM?? I have heard the Max Prop does because of larger blades. Help please. Thanks, George

 

I am far from a "prop genius", but you could reasonably conclude that if the new prop produces more thrust at the same RPM, it may be at the expense of the engine working harder.

 

With all things being equal (which they rarely are)...if the supplier is claiming higher thrust, it means, or is suggesting, they have a better open water efficiency. Since the thrust is proportional to the delivered power (same engine) and the speed of advance into the prop (same boat and stern arrangement) and then its efficiency. It may be just 0.001% better, but in the marketing world, a gain is a gain!

 

The area is important for highly loaded props, but for a typical cruising setup operating well off peak loading most of the time, there shouldn't be much in it. If the bigger area prop won't let the motor hit rated rpm, it probably won't produce more thrust then either. If you are burning less than a gallon of diesel an hour, does it really matter? Feathering props are inherently less efficient because of the flat blades. The geometric advance of the prop varies along the span of the blade. They also have to make room for the mechanicals, so have a bigger hub and fatter blade roots.

In the end, it depends on how well the original prop matched the motor, tranny and hull resistance. And on how Maxprop chooses to define 14P.

I'm surprised the Maxprop has a larger projected blade area than the Michigan wheel.

<edit> cross posted with Ad Hoc

 

http://www.peluke.com/marine-hardware/boat-props/

These folks have been making props that push better , not optimised for least drag under sail for 7-8 decades.

Well built and repairable. 2 blade , 3 blade , you choose.