Looking for any input aka real firsthand experience running them and with the company itself. At 4-5K each they are not a budget minded alternative lol but not anymore that Merc CNC's. I wouldn't run them on the Cat but may try them on the Center Console.

A biplane cannot be as fast as a monoplane and it is the same here, especially in surface operations, which is somehow comparable to supersonic flight.

I talked to them in person at the miami show 2 years ago. Not intended for performance use and they have no interest in our market. Very nice people though.

was only interested in them for possible CC... Definitely not for the skater LOL.

LARiverrat,

They are really designed for efficiency. The loop around the "tips" makes them run very "quiet", where "noise", from an aerodynamic/hydrodynamic standpoint translates in to lost energy. I doubt you'll see any real gains over a conventional prop unless you run the boat a lot. The instances where they will really pay for themselves is something like a commercial fishing trawler, where the boat sees a lot of running hours, and the fuel savings will start to add up.

Thanks. Brad.

ok whos going to cut the center of each blade of a good bravo prop out and test ? Sharrow is really focusing on the under 30 mph type of boats ,cruisers,trawlers,fishing, work ect.

Boost,

There's WAY more to Sharrow props than a slit cut in the blades.


Thanks. Brad.

brad i do know just when you think you figured out props here comes something new i was always shocked to see one bladed props on a few sailbotes there even was one on an aeroplane at a fly in breakfast around here talk about hurting your head!

Boost,

Yup. In the model boating world, props are kinda the last black art. There are guys that can really tune them in, but most of us were just winging it and watching for changes in speed/RPM/behavior. Software allowed one MFR to kinda revolutionize blade shape and has more or less dominated the market since.

These Sharrow props are, indeed, something completely different. The tandem blades seem to essentially be on the same blade plane, but one of them basically inverts as it make the bend around the "tip", creating a loop that both contributes to overall thrust, but also contains water washing radially off the tips of a conventional prop. This captured and redirected water not only contributes to the overall thrust, but significantly reduces noise (lost energy). It's pretty much the same technology that is at play in toroidal props we are seeing on drones. Check the story behind the guy that films orchestras with drones. At one point, he couldn't use the audio because of the noise of the drone props. This led to HOURS of editing and syncing. Once he started using the toroidal props, he could use the audio from the drone, allowing him to focus on specific musicians, both in video and audio.

I'm always drawn to the physics involved. Otherwise, we're all just winging it until empirical observation guides wisdom.

Thanks. Brad.

A propeller with one blade has the best efficiency, but unfortunately it is practically impractical.
The best propeller is the one that accelerates the water mass with the least parasitic resistance, that is, with the least disturbances in the flow. Some curves, which first bend the flow in one direction, then redirect it in another direction, are the exact opposite of this.

Is there any explicit explanation why this propeller is better than the classic ones? What I have read so far is all in the style of "National Geographic", which explains for an hour and says nothing.
I did not find anywhere, for example such datas:
- classic propellers can handle such a dynamic pressure in a certain regime, and our propeller can handle such a dynamic pressure.
- the best comparable classic propellers have such parasitic resistance, and ours has such.
- the best comparable classic propellers have such a slip on a sample vessel, and ours has such a slip.
- the best comparable classic propellers have such an efficiency on a sample vessel, and ours has such an efficiency.
- At some mechanical engineering universities, a diploma thesis sometimes appears with the title: "Calculation of the ship's propulsion", and at the end of it, a huge amount of data is covered in the form of diagrams. Could this be seen for this propeller?

For example why I miss reall datas:
"The special shape of the blade reduces noise, which reciprocally increases efficiency."
Has anyone considered how much db(A) means 500W of losses, if all of this goes into noise? Sound sometimes has no noteworthy connection to efficiency at all.