Slow is the wrong word, I think. Big container ships don't necessarily move a lot faster than sailing ships, since speed = fuel usage, which is a big cost in shipping. A big modern container ship might cruise at half it's maximum speed for this reason.
The main thing is modern container ships are much, much bigger than any traditional sail ship, which drives down the cost per shipped item. This particular article shows wooden ships with (I assume) comparatively big crews as you say, and I don't think those will be taking over international shipping again this side of a major economic downturn, but that doesn't mean that sail as a method of propulsion can't have a role to play in sustainable shipping.
You could construct sail ships with modern materials, and it's certainly possible to automate them to keep crew sizes down. I imagine you'd need a lot of fabric to move the Emma Mærsk when carrying 11,000 20' containers! But sail doesn't have to mean traditional methods and materials.
It might not be practical to make ships exactly as large as with fossil fuel propulsion. But if we're serious about efficiency and sustainability, in this and many other cases, we need to take a serious look at using renewable energy directly, rather than converting to electricity for storage and then back to kinetic energy.
The main thing is modern container ships are much, much bigger than any traditional sail ship, which drives down the cost per shipped item. This particular article shows wooden ships with (I assume) comparatively big crews as you say, and I don't think those will be taking over international shipping again this side of a major economic downturn, but that doesn't mean that sail as a method of propulsion can't have a role to play in sustainable shipping.
You could construct sail ships with modern materials, and it's certainly possible to automate them to keep crew sizes down. I imagine you'd need a lot of fabric to move the Emma Mærsk when carrying 11,000 20' containers! But sail doesn't have to mean traditional methods and materials.
It might not be practical to make ships exactly as large as with fossil fuel propulsion. But if we're serious about efficiency and sustainability, in this and many other cases, we need to take a serious look at using renewable energy directly, rather than converting to electricity for storage and then back to kinetic energy.