Interesting Propeller

[Russ]

Have you seen this before? Looks very interesting.
They don't currently make one for less than 150hp and they are a bit spendy ($5,000).
https://www.sharrowmarine.com/





Video

[kmclemore]

Yeah, I’d seen that too, Russ. But when you work out the cost vs any savings or extra power, it’s still a poor deal. But it sure is purdy!

[OverEasy]

Hi Russ!

Really interesting prop and presentation!
The efficiency and performance aspects are impressive!
There are a lot of very positive aspects in this uniqueprop design!
And yes, it sure is Purdy!
Thank you for sharing this!

Setting the cost aspect aside for a moment, there are a lot of nice features and performance to like about this novel prop design. While it w
Is currently marketed to a higher HP and Price Point crowd the design would still translate well down into the lower HP ranges, especially the 50 to 70 HP engines often found on Mac26X and M boats.

While the current models are Stainless Steel (which would help with the increased stresses imposed by high HP engines) it might be possible to make an aluminum version via investment or lost wax casting processes for the lower HP applications which could bring the prices down. A larger market of lower HP engines would also help with bringing down the purchase cost.

Getting a 1/3 or more improvement on available range isn’t small potatoes!

Again, Thanks for sharing this item!

Best Regards
Over Easy

[kurz]

Give me this prop

[Russ]

At $5,000 a prop, this prices it out of many captains.

The most interesting aspect was how quiet it made the engine.

It would be nice if this thing took off and they could increase production to reduce the price to reasonable. Or as OE states, maybe manufacture an aluminum version.

[kurz]

At $5,000 a prop, this prices it out of many captains.

The most interesting aspect was how quiet it made the engine.

It would be nice if this thing took off and they could increase production to reduce the price to reasonable. Or as OE states, maybe manufacture an aluminum version.

well, don't think it was the problem with the price for the first one... But you would buy a second... third one... becouse the others was stolen...

[OverEasy]

Anybody got a 3D Laser Metal Printer around that needs a project?
Printing one scaled for a 50 or 60 hp class outboard out of steel or aluminum for evaluation purposes (only) would make an interesting project. Getting it galvanized as a DIY really isn’t that hard either (with some simple reasonable precautions).

[Russ]

Nice point. Anyone have one and where are they located?

well, don't think it was the problem with the price for the first one... But you would buy a second... third one... becouse the others was stolen...

That would be an easy part to steal. Regular props get stolen easily.

[OverEasy]

Hi All!

This “Interesting Propeller” design approach also has application in moving air as in for drones and potentially in the future for aircraft.
Seems the genesis of the toroidal propellor was actually in current history developed for drones to quiet them down.
The link is below:
https://newatlas.com/aircraft/toroidal- ... ropellers/

Best Regards
Over Easy

[Russ]

OE, interesting link. This design offers a significant sound reduction for aircraft and drones as well.

[dlandersson]

New propeller?

[Russ]

[kmclemore]

I merged "Interesting Propeller" with "New Propeller?" as they relating to the same basic product set.

[Stickinthemud57]

These new prop designs look like they may have been computer-designed. Frankly, I am amazed at how good boat and airplane props got without the aid of computers.

As the price indicates, the disconnect between ideal design, the ability to mass-produce these designs, and the real-world cost-benefit analysis makes such designs more a curiosity than a must-have improvement IMO. At least until they can get the production costs down.

[OverEasy]

Hi Stickinthemud57!

Yeah your right, it is optimized with the help of computational fluid dynamics but it is a derivative innovation based upon older empirical analysis designs going back to the early 1900s and those as based on previous efforts going back at least hundreds of years BCE (and then some).
That takes nothing away from the current designers though!

There have been multistage tipshrouded aero and maritime props before now but not quite as demonstrably efficient or as slick looking. One could reasonably assume that earlier versions were more biased toward greater simplicity of design and practical manufacturability within their times abilities.

Helical single and multi blade screws within fixed and rotating cylinders go back into antiquity…does the Archimedes Screw come to mind? (Actually his was most likely based upon already in use designs prior to his era…)

Reaction vertical canted blade funnel fed axial shrouded turbines were in common use for driving water pumps and grinding grains going back at least 500 BCE and further into antiquity… People have been pretty creative and innovative for a very long time

Multi blade multi stage ducted (where the outer portion is stationary) and shrouded (where the outer portion rotates with the blades) have been actually been around for quite a while. They also have been subject to the same cost vs. benefit pressures as you point out… It’s often hard to compete with “good enough”…

As the biblical Solomon may have paraphrased from his predecessors “There really is nothing under the sun”

Best Regards
Over Easy