Here's a prediction - just like the past few times these have been posted, the thread will soon fill up with people saying they're impractical because they'd be too hard to cast, too expensive to CNC mill, and too weak if 3D-printed, because it hasn't occurred to them that you cast the prop hub, forge the blades, and weld them.
Or for the plastic ones, injection-mold them in pieces. I'm thinking snap together at the tips, and pin them together with the axle and/or screws at the hub.
would that work scaled up to a container ship? Those burn ~$100K of fuel per day, even 10% more efficient propellers could have ROE of one ~30 day round trip.
And likely the equivalent 10% gain in environmental efficiency.
On the curve displayed on the website linked there are places where the efficiency if far more than 10%. At 3000 rpm the efficiency gain was 44%. Imagine if you could cut both fuel usage and environmental emissions by ~40% simply by changing a prop.
The competitive advantage of changing props could drive a close to 1% reduction in overall CO2 emissions, given that the shipping industry accounts for about 2% of global emissions. The constant smog around ports could also be partially reduced, reaping health gains.
Potentially you may not need as strong a sonar emitter either, since the signal to noise ratio should be improved if you isolate out prop noise (I know, thats a long bow to draw, and they may not overlap, but still important to consider in overall oceanic health)
When life imitates art; highly recommend "The Hunt for Red October" (adapted from Tom Clancy's 1984 novel) about the Soviet Unions' secret development of a new type of submarine that proves to be undetectable to passive sonar.
People do! there were many different approaches - small winglets on propeller tip, propeller with a ring, propeller in a tunnel (turbine) - and they all improve performance by a bit.
This is a next iteration, seems to be harder to simulate but improves on previous ideas.
