They claim 7-10% reduction in fuel usage, with fuel making up 60% of their total costs.
Given that they soon expect to be spending $5 billion/year on fuel for 800 ships, fuel spend is a bit north of $6 million/year for an "average" ship. But size seems to vary widely (they note that only the 80 of their largest ships are being considered for these sails).
At an installation cost of $2 million, saving 10% of an "average" ship would return 600k per year, or a 3.5 year paypack, which seems well worth doing where possible. And they'll obviously get better than that on their 80 largest.
Not a magic bullet by any means, but certainly seems worth using.
I think that's something we lose sight of in software sometimes, where we're used to some token effort improving performance by 10x or more. In the real world, if you can make something 10% more efficient, that's a game changing, industry conquering advantage.
Too true. Like the new dodge ram etorque, using its electric motor to replace the alternator, it can launch the truck and let the combustion motor take over at highway speeds. 1-2 mpg is a large improvement for a truck. 1500 dollar option that pays for itself, and a good step towards getting battery tech into trucks.
I've seen it mentioned boats/ships using electric assist will also be another catalyst for battery tech integration, fuel costs on those large ships are always a topic.
Bolt on solutions that are affordable with quick turn around on investment.
- Some degree of competition in the industry exists (otherwise the capital could be used to increase revenue or acquire small potential rivals before they're too large to afford, among other higher return places to spend the capital)
- The industry is mature and sources of larger savings already exhausted
- Prospect for some future much bigger savings small (or at least not in conflict with the current effort)
- Prospect for the industry as a whole very good (in a shrinking market, 10% savings becomes lower priority than selling off assets quickly enough at high enough cost without subsidizing a competitor or startup)
- Industry consolidated enough (or capital costs of the improvement low enough) to finance the upfront cost
I'd guess (no real evidence) it could be because a lot (most?) software runs on timescales where 10% isn't that significant. Also, maybe something to do with Amdahl's law, where speeding up one part by 10% rarely speeds up the whole thing by the same amount?
As long as they are reliable and have non-crazy maintenance costs it should be profitable now. I imagine some time and competition could cut that install cost in half too.
> Rotor ships take advantage of this same effect by spinning a large vertical cylinder, typically using an electric motor, and using the resulting force for propulsion.
I always thought sails were partially defined by being passive. I wonder why these aren't called "rotor fans" if they're electrically driven?
Is there anywhere it's discussed when rotors are expected to outperform normal fans? They seem to be used only on large ships, but I can't see a first-principles explanation for that.
Regular sails actually work similarly to a wing, in that pressure differentials on either side create a force we call lift on a plane, rather than simply being "pushed from the back" by directly catching the wind. That's why a sailboat can go in almost any direction regardless of which direction the wind is blowing.
Watching bleeding edge yachts sail is always interesting. Hydrofoils achieve speeds greater than 3x wind speed though their stability doing it is a bit alarming.
I'm really interested in how dimpling would affect the drag/lift properties of these.
Years ago on /. I saw a post about how wales bumps on the leading edges of their fins/flippers were to increase/modify the eddies around their fins in such a way as to provide them more thrust (or something, it's been years since I read the article) - and I was curious what it would look like to have helicopter blades with leading edge bumps on them similar to wales...
So, I'd like to see what dimples both convex and concave would have on the surfaces if these - like a golf ball.
Also, if you have never done it, take a cylindrical plastic cup and, in a bathtub full of water spin the cup as hard as you can on the surface of the water - like a top - and see how long you can get it to stand up. Kids like this trick.
I always thought it would be interesting to have a barge like flat boat on top of several cylindrical feet like floats, which can spin rapidly along the Z access and use it as thrust.
Yeah, but they are motor driven. So how much of the propulsion comes from the motors, and how much from the wind? Given the relatively small reduction in fuel cost, I'm guessing that most comes from the motors.
They explain that in the article, and the fact that it newer tech and lighter columns to get a net benefit.
Having grown up in France, I knew about Cousteau's Alcyone (it was a big deal at the time) and had been wondering why it hadn't been used more since then.
Apparently this is a turbo sail and not the same as the Flettner rotor. The Wikipedia article you linked to mentions the same. Ones powered by electricity and one by air? Both seem to take advantage of the Magnus effect though
Given that they soon expect to be spending $5 billion/year on fuel for 800 ships, fuel spend is a bit north of $6 million/year for an "average" ship. But size seems to vary widely (they note that only the 80 of their largest ships are being considered for these sails).
At an installation cost of $2 million, saving 10% of an "average" ship would return 600k per year, or a 3.5 year paypack, which seems well worth doing where possible. And they'll obviously get better than that on their 80 largest.
Not a magic bullet by any means, but certainly seems worth using.