sharrow propeller. a revolution?

[Brusky1000]

You have to read a lot of ego inflation BS to finally get to this. Didn't read anything about patents, but might have missed that in the rhetoric.

After our testing and driving the boat with all three props, our conclusion is the following. The Sharrow Propeller™—

1. Performs significantly better at idle.

2. Plans at a lower RPM

3. Is faster at all RPM settings

4. Gets significantly more mpg at 3000 and 3500 RPM

5. Is more fuel efficiency at every speed-through-water setting

6. Is as much as 18% more fuel-efficient at 26-28 MPH

7. Produces the highest top speed

8. Creates noticeably less vibration

9. Is generally quieter

10. Has superior handling in tight turns at high-speed

11. Improves handling in reverse

12. Provides the greatest range at all speeds

 

[DDW]

Just some back of the envelope calcs:

This year I did about 2000 miles, using 540 gallons of diesel. I'm sure some did much more, but I'd guess that is above average. If I saved 15% in fuel, 81 gallons at $2.80, I'd have saved $227. A new ordinary prop for my boat is about $2000. The Sharrow looks like it'd be more, suppose $3000. I'd break even on it at 13 years and 3 months. Quite a bit longer, if the time value of money is considered. And assuming it survived that long in the PNW driftwood.

Probably makes more sense in commercial continuous use. Or if I ruined my current prop and had to buy a new one anyway so that only the difference had to be justified. Swapping just for the fuel savings? Probably not.

 

[High Wire]

With 3D printer technology breakthroughs coming, in the near future it may be cheaper to print out a new one than to repair the damaged old.
Something as complex as the Sharrow should be a perfect use for that tech.

 

[Brusky1000]

Print your way to the future

I've even seen aeronautical parts that phase from copper to steel without welding.
Amazing.

 

[danderer]

It is impressive how much research has been done on propellors over the past 150 years. The RN and USN as well as private industry have built dedicated facilities with teams of sharp people to look for designs that are more fuel-efficient, quieter, and allow higher speeds -- not all necessarily in the same design, of course.

Here is just one example: https://www.ingenia.org.uk/Ingenia/Articles/b8e6d8ae-101d-4c44-91d6-5be05cb78e49

Now it is possible that Sharrow has found something that all these others have missed. I'm on the wait-and-see side.

I'm also still waiting for cold fusion.

 

[rslifkin]

Now it is possible that Sharrow has found something that all these others have missed. I'm on the wait-and-see side.

New things wouldn't necessarily have been missed by the others, but it's possible the others didn't explore certain shapes or designs just due to it not being practical to build or test at the time of the research.

 

[Ski in NC]

I'm sure Sharrow would be welcomed at one of those hydrodynamics lab to test his wheel. Maybe that has already been done.

We shall see. I'm in the wait and see mode myself.

 

[Brusky1000]

It is impressive how much research has been done on propellors over the past 150 years. The RN and USN as well as private industry have built dedicated facilities with teams of sharp people to look for designs that are more fuel-efficient, quieter, and allow higher speeds -- not all necessarily in the same design, of course.

Here is just one example: https://www.ingenia.org.uk/Ingenia/Articles/b8e6d8ae-101d-4c44-91d6-5be05cb78e49

Now it is possible that Sharrow has found something that all these others have missed. I'm on the wait-and-see side.

I'm also still waiting for cold fusion.

As a PE with BS and MS in Nuclear Engineering, I applaud your patience regarding cold fusion. Don't hold your breath. ;-)

 

[OldDan1943]

It is public knowledge by now, the new fast attack subs are using something akin the same water jet drive as the ski doodle.

Of course, cavitation is a function of pressure. At greater depth and pressure, the less the cavitation is a problem.

As the prop spins, the tips create a low pressure area, hence cavitation.

Dont ask me how I know. Your security clearance is not high enough.
As a nuclear power train machinist mate on FBM subs, I had many jobs including throttle man.
Dont make the lights flash.

 

[Nomad Willy]

I think the most likely place to see one of these props is on a big tug.

 

[OldDan1943]

I think the most likely place to see one of these props is on a big tug.

They used to have tug boat races on the Detroit River. The racing props were considered "top secret" from the other racing tugs.

 

[GoneFarrell]

I think the most likely place to see one of these props is on a big tug.

Could be. Would like to compare this to Kort nozzled propulsion, they're good for big thrust at low speeds. But they wind up being too much drag for recreational trawlers, IMHO.

Did you ever cross paths with a guy named Nils Lucander? I did, we had several interesting dialogs by snail mail on this kinda stuff back in the days before internet.

 

[rsn48]

I have just finished repowering my express cruiser engine and leg with a Merc 6.2 l 350 hp and a Bravo 2 leg. I haven't purchased a prop for this boat yet but I am seriously contemplating this new one and I hope they meet their deadline for the Miami boat show in early Feb. My boat won't be in the water till late march or early april. I'm hoping they have something for my Bravo 2.

A couple of items interest me. 1) Better reverse performance, I am moored in a horribly tight marina. I have added a bow thruster but if this makes the boat go straighter with less prop walk, count me in.
2) Faster to plane, what not to like?
3) If their aluminum prop out performed stainless steels props, that's not suppose to happen right?

 

[MurrayM]

Living where we do (marinas are few and far between) we’d consider one for the range extending factor so we could stay “out there” longer before having to come in for fuel.

 

[diver dave]

As a nuclear power train machinist mate on FBM subs, I had many jobs including throttle man.
Dont make the lights flash.

Thats awesome. Can u at least tell us how much shaft HP at the other end of the throttle?

 

[oscar]

Dont make the lights flash.

Same thing 5 miles up.....

 

[OldDan1943]

Thats awesome. Can u at least tell us how much shaft HP at the other end of the throttle?

Nope. To be honest, I do not recall.

 

[markpierce]

Have commercial ships bought into the concept?

Regardless, what would be the rate of return (fuel efficiency) on investment?

 

[MurrayM]

Have commercial ships bought into the concept?

Regardless, what would be the rate of return (fuel efficiency) on investment?

Some things are beyond the bottom line, such as around 10% less bunker fuel emissions from an estimated 5 billion barrels burned per year by the international shipping industry. No small amount!

 

[FF]

"Would like to compare this to Kort nozzled propulsion, they're good for big thrust at low speeds. But they wind up being too much drag for recreational trawlers,"

Above about 12K the extra drag is, well a drag.

For the displacement folks the only loss is the prop steering which is a great help at times docking.

 

[Simi 60]

Everything that's old is new again?

Spotted today

 

[High Wire]

There’s a center console boat on my dock with two of the sharrow props on twin 250 hp Yamaha outboards. Kaching! Hope to talk with him sometime.

 

[mcarthur]

Everything that's old is new again?

Spotted today

Love the "Conversation starter"!

P1: What's that?
P2: It's a screw.
P1: you've lost a big one there, definitely not many left.
<end of conversation>

 

[DDW]

Everything that's old is new again?

Spotted today

Might make any Sharrow patents validity questionable.

 

[GoneFarrell]

I think that prop was done that way to take a beating on a beach landing then back off without busted blades, not really Sharrow's mission profile. Interesting nonetheless.

 

[Blissboat]

Might make any Sharrow patents validity questionable.

That was my first reaction, as well. Not suggesting any bad intent on the part of Sharrow, but if this is indeed what the advertisement claims, then someone appears to have beaten them to it.

 

[OldDan1943]

That was my first reaction, as well. Not suggesting any bad intent on the part of Sharrow, but if this is indeed what the advertisement claims, then someone appears to have beaten them to it.

The original design is very robust compared to the current edition

 

[twistedtree]

Might make any Sharrow patents validity questionable.

Indeed.

 

[Hippocampus]

Have wondered about bang for your buck. What makes more sense a CPP or a sharrow on a hull run at various rpm?
Would think the sharrow is tuned to a particular rpm and load factor. Not an issue with an outboard which is most commonly on plane but possibly an issue for a FD hull run in widely varying conditions or a SD hull run at various speeds.

 

[twistedtree]

Have wondered about bang for your buck. What makes more sense a CPP or a sharrow on a hull run at various rpm?
Would think the sharrow is tuned to a particular rpm and load factor. Not an issue with an outboard which is most commonly on plane but possibly an issue for a FD hull run in widely varying conditions or a SD hull run at various speeds.

Couldn't you equally tune a conventional prop for some specific operating point?