It is worth noting that rigging and sails for lightweight racing hulls has evolved way beyond anything that has ever been used commercially -- And would look quite weird (though still recognizable) to a 19th C sailor [0].
Also, the material science involved in creating laminated sailcloth is very close to state-of-the-art.
Of course, racing yachts go fast because they weigh very little.
Also, Kitesails [1] have been proposed many times over the last few decades, but I've not heard of anyone using one commercially.
Sails just don't provide all that much motive force, and they're far too unreliable (wind dies down, it doesn't matter how much sail you have.)
Maybe the GP was thinking more along the lines of general 'green' tech -- wind turbines, solar panels, etc? It would certainly be cool to see more of those to supplement existing propulsion systems on ships, and that would help reduce the amount of fuel burned for shipping, which uses some of the dirtiest fractions of petroleum.
Combining technologies would absolutely be a great way to pivot, as the article shows. Maybe it’s a dumb question, but why don’t we have sails on modern ships as a supplement?
I just lament that we basically completely abandoned such a great mechanism (sails) so haphazardly just because coal was cheap & reliable; now the environment pays the price.
Sails take quite a bit of space to store, they aren't exactly the lightest thing, and you need training and coordination of the sailors to deal with them. They also probably just dont provide enough benefit to offset the costs -- as I said before, sails don't actually provide that much force.
There are a lot of smaller boats that have both sail and mechanical engines, but that only works because they're small enough that the sails can provide a significant amount of force. And if you look at the transition period between the Age of Sail and Age of Steam, there were a lot of boats and ships that had both sail and steam engines. The sails were mainly relegated to backup, or to help out the steam engines, but these hybrids existed.
At 10 mph wind, sails generate about 0.256 pounds of force per square foot (according to random website found via google). Therefore your several ton cargo ship gets next to nothing from sails.
As someone who was a racing dingy sailor in his youth, the answer is a gob smacklying lot of improvements have occurred in my lifetime, mostly this century.
The first thing that hits you is the hull isn't in the water. The next thing is the sail boats in a modest breeze are giving the powered boats a run for their money speed wise. One thing that is not so obvious is the sails are now more aerofoils.
Back in the day, boats that had no hulls were a mad mans dream. Now we call them kite surfers. Some exotic ones have keel hanging from a bit of rope.
I’m no expert, but it’s possible that advances in material science, our understanding of wind & ocean currents, GPS, etc. over the last, what, 150 years? all could massively improve efficiency.
As far as I know, humanity was still improving sailing tech till the steam engine dominated it. I guess my point is that it’s impossible to tell where we could’ve been now without actually having those years of iteration & innovation; the steam engine quickly and abruptly stymied all developments on that front.
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I’m genuinely curious, what innovations could there possibly be for sails beyond increasing surface area or either the sails or the keel?
It is worth noting that rigging and sails for lightweight racing hulls has evolved way beyond anything that has ever been used commercially -- And would look quite weird (though still recognizable) to a 19th C sailor [0].
Also, the material science involved in creating laminated sailcloth is very close to state-of-the-art.
Of course, racing yachts go fast because they weigh very little.
Also, Kitesails [1] have been proposed many times over the last few decades, but I've not heard of anyone using one commercially.
[0] https://en.wikipedia.org/wiki/Wingsail
[1] https://cleantechnica.com/2018/09/11/airbus-seawing-kite-sai...
Skysails[1] sells them commercially. I cannot find how many ships operate those other than two "prototypes"[2]
[1] https://www.skysails-group.com/
[2] https://de.wikipedia.org/wiki/SkySails#Treibstoffeinsparung
They don't work like a traditional sail but "rotor sails" are a fairly recent innovation and seem interesting: https://en.wikipedia.org/wiki/Rotor_ship
I've seen articles here and there about adding them to tankers to increase fuel efficiency.
I can't imagine there would be that many.
Sails just don't provide all that much motive force, and they're far too unreliable (wind dies down, it doesn't matter how much sail you have.)
Maybe the GP was thinking more along the lines of general 'green' tech -- wind turbines, solar panels, etc? It would certainly be cool to see more of those to supplement existing propulsion systems on ships, and that would help reduce the amount of fuel burned for shipping, which uses some of the dirtiest fractions of petroleum.
Combining technologies would absolutely be a great way to pivot, as the article shows. Maybe it’s a dumb question, but why don’t we have sails on modern ships as a supplement?
I just lament that we basically completely abandoned such a great mechanism (sails) so haphazardly just because coal was cheap & reliable; now the environment pays the price.
Sails take quite a bit of space to store, they aren't exactly the lightest thing, and you need training and coordination of the sailors to deal with them. They also probably just dont provide enough benefit to offset the costs -- as I said before, sails don't actually provide that much force.
There are a lot of smaller boats that have both sail and mechanical engines, but that only works because they're small enough that the sails can provide a significant amount of force. And if you look at the transition period between the Age of Sail and Age of Steam, there were a lot of boats and ships that had both sail and steam engines. The sails were mainly relegated to backup, or to help out the steam engines, but these hybrids existed.
I just looked into the economics of rotor sails.
On average, they save $400/day ($146,000/year) in fuel costs (2017) or about ~10% of fuel consumption. In real terms, it's not much.
They cost about €1-2 mil ($1.1-2.3). Under the most ideal circumstances, that is a ~8 year payback, which is fairly long.
In order for the economics to work out, oil prices need to be higher and externalities (CO2 emissions) need to be included in the price.
We do. They just don't look like sails. This is a Maersk ship.
https://en.wikipedia.org/wiki/Rotor_ship#/media/File:Norsepo...
Low tech magazine has some practical examples of ships that operate sails in addition to fuel to lower fuel-usage: https://www.lowtechmagazine.com/2007/09/sailing-ship-re.html
At 10 mph wind, sails generate about 0.256 pounds of force per square foot (according to random website found via google). Therefore your several ton cargo ship gets next to nothing from sails.
We use the form factor quite differently. A game and watch is about the size of a cell phone these days.
As someone who was a racing dingy sailor in his youth, the answer is a gob smacklying lot of improvements have occurred in my lifetime, mostly this century.
Have a look at the America's cup races. Eg: https://www.youtube.com/watch?v=Y325JWyRslE
The first thing that hits you is the hull isn't in the water. The next thing is the sail boats in a modest breeze are giving the powered boats a run for their money speed wise. One thing that is not so obvious is the sails are now more aerofoils.
Back in the day, boats that had no hulls were a mad mans dream. Now we call them kite surfers. Some exotic ones have keel hanging from a bit of rope.
I’m no expert, but it’s possible that advances in material science, our understanding of wind & ocean currents, GPS, etc. over the last, what, 150 years? all could massively improve efficiency.
As far as I know, humanity was still improving sailing tech till the steam engine dominated it. I guess my point is that it’s impossible to tell where we could’ve been now without actually having those years of iteration & innovation; the steam engine quickly and abruptly stymied all developments on that front.
Only thing I could think of would be a hybrid boat...sail + solar powered / wind powered electric motor?
Off the top of my head:
- Motorised rotation of the sails to capture the wind.
- Automated tacking.