Hydrodynamic drag on many smaller hulls is larger than on one big one.
Ports cost money. It seems hard to make a port which unloads individual 1-container vessels faster than a conventional port can pull containers off a large vessel using cranes. As for just making more numerous & smaller ports, it probably ends up being much more expensive.
It’s an existing technology for large ships to fly kites to save fuel when the weather is favourable and the wind is blowing in the right direction. I think most ships still don’t do this, so I’m not sure if it’s currently economical, but it at least demonstrates that making a ton of tiny sailboats is not the only way to take advantage of the wind. Sailboats have a lot of moving parts, and maintenance on so many of them would be a nightmare.
Even though containers have taken over a lot of things, not all loads are containers even today, so we still need large ships for fuels and bulk cargo.
I was referring to the older style of sailboat design, like this one, where the sails are all controlled by a bunch of ropes. Single rotating airfoil sounds a lot simpler. One advantage of an airfoil over a kite is that it would allow the ship to gain some propulsion, even when travelling at an angle upwind, right?
Obstacles to this idea:
Hydrodynamic drag on many smaller hulls is larger than on one big one.
Ports cost money. It seems hard to make a port which unloads individual 1-container vessels faster than a conventional port can pull containers off a large vessel using cranes. As for just making more numerous & smaller ports, it probably ends up being much more expensive.
It’s an existing technology for large ships to fly kites to save fuel when the weather is favourable and the wind is blowing in the right direction. I think most ships still don’t do this, so I’m not sure if it’s currently economical, but it at least demonstrates that making a ton of tiny sailboats is not the only way to take advantage of the wind. Sailboats have a lot of moving parts, and maintenance on so many of them would be a nightmare.
Even though containers have taken over a lot of things, not all loads are containers even today, so we still need large ships for fuels and bulk cargo.
From the papers I’ve seen, using sails on large cargo ships seems economically practical for up to 1⁄3 of their overall propulsion.
A sail would be a big rotating airfoil on a pole. Here’s an example. What maintenance issues are you thinking of?
Oh, cool, that’s great.
I was referring to the older style of sailboat design, like this one, where the sails are all controlled by a bunch of ropes. Single rotating airfoil sounds a lot simpler. One advantage of an airfoil over a kite is that it would allow the ship to gain some propulsion, even when travelling at an angle upwind, right?
Well, even the old fabric sails act as airfoils, they’re just not very good ones.
Another approach is to put an actual wind turbine on the ship; it’s more competitive with sails than you might think.