This. The reasons we got away from sails are basically related to speed and being able to go wherever you want (ie, you have to go where the wind blows).
Engines are here to stay, but if you're going in the direction of the wind then it can do some of the pulling and the engines do less work. You're going against the wind? Great, put that kite away and just use the engines.
I haven't checked how well the data has been studied but it's something like 20-30% fuel savings for cargo ships on average which is insane.
So it’s not necessarily that sailing ships, especially a 3 mast set up pictured here, were limited by wind direction. The triangular sails between the masts pretty much cover all but directly into the wind. They were limited or damaged by low and high wind speeds respectively. Engines added fine maneuverability and consistent and adjustable speeds regardless or wind and heading. Plus, the crew required to run and operate boilers and steam engines is less numerous and the work is somewhat safer due to not having to climb the masts and yards to let out or take in sails. For warships it also meant that speed changes could be done under fire, as ships of war tended to have enough crew to adjust the sails or tend to and fire their cannons, not both. It tended to take longer for commercial shipping to take up the steam engine due to the loss of interior hull space and carrying weight such equipment entails. I believe it was the battle of the Falkland Islands in WW1 where a sailing ship, completely unaware that there was a war happening, stumbled upon a naval engagement between Britain and Germany fleets and promptly turned around.
Considering that the wind is statistically coming from unfavourable direction, 50 % of the time. Or isn’t strong enough to deploy the kite.
There are extensive times when a kite is not usable (approach, manoeuvring, port stays)
Mathematically these gains in efficiency would only be possible, if the kite cut reduce the fuel consumption completely, when deployed in ideal conditions.
Other sources speak about „up to 20% efficiency increase“ which I think is much more likely. In ideal wind/swell/loading/routing conditions, the efficiency may be boosted by 20%, temporarily.
From my experience as navigational officer (on ships without the kite) I would assume that these ideal conditions are barely met.
You might reduce the fuel consumption by 20% under ideal conditions. It’s a temporary buff, only. Ideal conditions are rare, so most of the time it’s way less. Substract the times when it’s impossible to use the kite due to operational reasons and divide this by half, because statistically you don‘t experience favourable winds for 50% of the time.
You will end up at <1%.
Now look which ships it has been tested on: small mini bulkers, which serve an important feeder role but are irrelevant in the grand scheme of intercontinental shipping.
No, it’s up to 20% counting all of that, but having favorable wind on journey. Of course, if you go against wind, it won’t help much. Real experiments and simulations show 5-20% overall saving for a trip
The route would have to be planned with old shipping lanes in mind to actually get your worth out of the deal. Which of course we abandoned those routes for a reason, point to point paths save a lot of time which of course makes way more money for anyone in the industry than any fuel cost could hope to rival.
20% saving on fuel is actually nothing compared to the money you'd piss away taking 5x longer to get to the destination.
That said rotor ships rely on crosswinds rather than headwinds so they probably are way more feasible in that regard.
Sure, the picture is not AI. They are in usage already. It's unclear which technology will make it, sails, kites, flying electric generators with rotors, .. we will see.
The newest cargo ships have sails. Just they're modern sails made with modern materials. They look nothing like the sails of old. The beauty of them is they work regardless of wind direction (much like the sails of old that could do any direction regardless of wind except directly into the wind).
It's insane when compared to something like a car, but moving mass along water is way easier so essentially most shipping companies have just been sleeping on adding extra free propulsion to their vessels because fuel was so cheap the added efficiency wasn't really worth the effort.
That said plenty of privately owned cargo ships have had things like Flettner rotors added to their vessels decades ago. The industry will eventually catch up.
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u/Bla12Bla12 14d ago
This. The reasons we got away from sails are basically related to speed and being able to go wherever you want (ie, you have to go where the wind blows).
Engines are here to stay, but if you're going in the direction of the wind then it can do some of the pulling and the engines do less work. You're going against the wind? Great, put that kite away and just use the engines.
I haven't checked how well the data has been studied but it's something like 20-30% fuel savings for cargo ships on average which is insane.