More on the Sharrow propellers

[Top Hatt Craig]

Seems to be gaining ground in acceptance, if only for those about to change props for another reason... http://www.sharrowengineering.com/recreational/

 

[Dan Mapes]

Stronger, more efficient, and etc..

If it's so good someone racing must be using it. Wait......

 

[Top Hatt Craig]

Whoops, didn’t include link to test by Boat Test.com.. https://www.facebook.com/SharrowEngineering/videos/397114247876093?sfns=mo

 

[scottinsydney]

I just watched this video... fascinating. It might possibly mean my 2005 200hp Mercury 2 stroke would be somewhat as fuel efficient as today's 4 strokes. If that's true, then its a cool upgrade.

 

[krush]

The test results are not surprising. There is much more blade surface area with the new prop (which explains planning at lower RPM). This has historically always been a problem for outboard and I/O engines...they are limited in the diamter prop they can use. Everybody knows bigger/slower turning is more efficient at moving water with less slip (well, at least those with solid understanding of engineering concepts). It's the same reason Pratt made the geared turbofan engine (https://pwgtf.com/)

Big gains on outboards and runabouts, but I'm very skeptical if such improvements will occur on larger applications like our boats and ships--the latter two do not face the physical space constraints that outboards have.

 

[oscarvan]

Big gains on outboards and runabouts, but I'm very skeptical if such improvements will occur on larger applications like our boats and ships--the latter two do not face the physical space constraints that outboards have.

No, but if you want to make the larger boat props bigger, in order to maintain clearance you are either lengthening the strut, which increases shaft angle and with it decreases efficiency, or you are carving out prop tunnels which is not a realistic idea on existing (old) boats.

 

[krush]

No, but if you want to make the larger boat props bigger, in order to maintain clearance you are either lengthening the strut, which increases shaft angle and with it decreases efficiency, or you are carving out prop tunnels which is not a realistic idea on existing (old) boats.

Your point is true for a refit. But most ships/large boats are designed originally to fit the required size prop. It's definitely a cool idea and I hope it goes places.

 

[piripucha]

I do not want to punch their party baloon, but I just hope that someone made a good material/stress analysis.. My gut tells me something is about to break !