Marine

Hubless propeller mimics whale flippers for improved drag and efficiency

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The BlueSpin stationary sail drive attaches to the hull underbody; this one includes the traditional propeller design, not the new Whale version
BlueNav
BlueNav's new Whale Design propeller blades feature tubercle-inspired bumps on its edge and striations on its body
BlueNav
BlueNav's add-on BlueSpin drives give boat owners a way of easily hybridizing their vessels for better efficiency
BlueNav
The BlueSpin stationary sail drive attaches to the hull underbody; this one includes the traditional propeller design, not the new Whale version
BlueNav
Rather than focusing on fully electrifying boats, BlueNav's mission is to help customers hybridize existing vessels
BlueNav
BlueNav is preparing to give its BlueSpin hubless electric drives a whale-inspired propeller system
BlueNav
BlueNav teases the shape of its blades ahead of the 2024 Boat Düsseldorf show
This humpback whale gives the world the flipper, providing a good look at its tubercles
BlueNav BlueSpin outboard
BlueNav
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French electric marine drive specialist BlueNav is preparing to put a more natural spin in its lineup. The all-new Whale Design propeller features blades that follow the contours of a whale to improve system efficiency. The unique propeller is set to debut in the company's electric outboard and inboard drive systems to further improve upon the efficiency and versatility they add to existing boats.

Founded in 2020, BlueNav is focused on the gradual electrification of private and commercial boats. In contrast to companies focusing all their energy on pure-electric boating, BlueNav has taken a hybrid tack, developing "BlueSpin" electric propulsion solutions designed to be used in conjunction with a boat's original combustion engine.

The add-on electric propulsion introduces readily available near-silent, zero-emissions electric cruising and an overall reduction in on-water emissions, without giving up the range and power of a combustion engine. The retractable design of the BlueSpin outboard and inboard systems means they can be easily pulled out of the water when the captain wants to proceed in combustion mode. Having an all-electric option is especially valuable for navigating through protected waterways where combustion engines are banned.

BlueNav sums up its approach: "Recognizing the impossible batteries challenge for immediate widespread adoption of electric mobility, BlueNav has focused on bringing today’s mobility to life by developing alternative solutions with hybrid propulsion. Designed for boaters and professional vessels, BlueNav motors allow any type of boat to be converted into a hybrid-electric vessel, today."

In the same way some automakers and drivers believe that hybrid vehicles are a more practical step than pure EVs for emissions-cutting in the short term, BlueNav believes hybrid drives are the best immediate way forward for boats. And having seen years' worth of paltry battery-electric boat ranges, it's hard to find fault in the logic.

As for its latest innovation, BlueNav looked to the humpback whale as a point of inspiration, zeroing in on its flippers. In place of the smooth, slippery edge one might expect to find on a creature of the sea, the humpback's flipper has a very bumpy edge. Bony bumps called tubercles line the flipper's leading edge, and have been found to improve hydrodynamic efficiency by channeling water flow, reducing drag, increasing lift and improving maneuverability.

This humpback whale gives the world the flipper, providing a good look at its tubercles

BlueNav's engineering team studied the efficacy of these whale tubercles, and undoubtedly previous propeller work of this vein, and used CAD to apply it to its own propeller design, replacing the smooth leading edge with tubercle-inspired crests. Computational Fluid Dynamics (CFD) was then used to analyze predicted performance over a variety of thrust ratios.

According to BlueNav, the crested blades improve flow around the troughs, changing the pressure and speed of the downstream water and increasing thrust and overall power output. The company has also laid gentle striations in the propeller surface to mimic the low-friction nature of the whale's body, further optimizing performance.

BlueNav's new Whale Design propeller blades feature tubercle-inspired bumps on its edge and striations on its body
BlueNav

BlueNav developed the Whale Design propeller for integration into its BlueSpin hubless electric prop drives. In place of a common shaft-mounted propeller, the BlueSpin motor places the propeller blades on a magnetically driven inner ring. The company says the design minimizes friction for improved efficiency, operates more quietly, and requires fewer components and less maintenance in comparison to a traditional hub-prop drive. BlueNav offers outboard, in-hull and stationary under-hull configurations to meet the needs of different vessels.

BlueNav revealed the Whale Design at the Düsseldorf boat show in January and plans to begin offering the Whale prop BlueSpin models for order in the coming weeks. It will sell three-, four- and five-blade configurations and tells us the new blades will not tack any additional costs on the price of the BlueSpin drives.

Source: BlueNav

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7 comments
byrneheart
Did I miss the part where there was any data?
Aross
Not much meat to the article. Would like to see more statistical information in terms of power, thrust, run times and of course price range.
Adrian Akau
An article on efforts to improve aerodynamic efficiency on vehicles would be most appreciated.
Chris Centers
It’s a pretty good idea - I had the same idea nearly 10-years ago, sketched out and fully documented. The question I have is, how is the elect drive configured?
Ray6969
Like byrneheart below says, where are the stats?
Expanded Viewpoint
It says right there in the article that the inner ring is magnetically driven, so imagine taking the rotor out of an induction motor, and opening up the holes in the end plates that hold the shaft bearings to nearly the OD of those plates. Put in some rings of Teflon to be the new bearings, and slip the tube with the blades into it. Of course the tube with the blades would need to have some steel or other magnetic material cast into it so the rotating magnetic field from the windings in the shell would interact with it. There are reversing electric motors on the market, so to get reverse direction of the pump, you just energize the other set of windings. An alternator with three phases like all car and truck alternators of today use, would be perfect! You just swap any two of the three phases, and the motor will reverse direction!
veryken

Looks like my clog-prone drain.