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Comment by silicaroach | Hacker News Reader

Finally, a proper look at the cost in most respects of the real cost of a 'sustainable' technology. We need more of these but no one will pay nor pay attention.

Unfortunately though, sail driven ships are kind of useless for the efficient movement of cargo. Masts are required and take away stowage space and, more importantly, make efficient cargo loading/unloading impossible. Read the book "The Box" to understand the changes brought about in cargo shipping over the last century.

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Instead of sails we could try other methods, like kites, or that weird turning-metal column effect. To name two serious proposals I've seen

I assume you’re referring to the Coanda effect.

I think rotor sails leverage the Magnus effect, not the Coandă effect.

Good news on the “weird turning-metal column effect” front: they just installed five tilting rotor sails on a newlybuilt bulk ore carrier.

https://gcaptain.com/newbuild-vale-vloc-revealed-as-bulk-car...

Why is this important? It shows that the ship owners has seen enough promise in the technology to overcome the potential risks. If it works out well for them we will very likely see wider adoption.

How does this work? The article assumes I should already know the mechanics of it, but googling only seems to turn up a bunch of the same sorts of articles.

I'm not an expert on it really. They rotate the giant cylinder and the wind is blowing by. The rotation forms a low pressure zone one side of the cylinder which acts as a lift force perpendicular both to the rotational axis of the cylinder and the wind.

It's the same effect which "turns" a soccer ball if you kick it with a spin. There is a really nice demonstration of the effect in this video: https://www.youtube.com/watch?v=2OSrvzNW9FE

This wikipedia page has a way better summary than my attempt above: https://en.wikipedia.org/wiki/Rotor_ship

From that article:

"If the pilot proves effective, it is estimated that at least 40% of the fleet will be able to use the technology, which would result in a reduction of almost 1.5% of Vale’s annual iron ore maritime transport emissions.”

Well, that's a step in the right direction so something to be applauded. But taken alone, an emissions reduction of "almost 1.5%" isn't going to save the planet.

Tanker boats could probably use sails without loading and unloading getting in the way. I would imagine it's just hoses and pumps to get the liquid out.

Exactly, and these are precisely the vessels that can most handle slower transfer speeds - as you just have more sailboats to make up for slower speeds/smaller sizes. All that matters is how many arrive each day, as the cargo is fungible.

In fact, doing such would provide a buffer that could help prevent supply shocks.

At what point does the additional resource of building a lot more ships (which have more crew, eating more food, producing more waste) result in a net negative?

Oceangoing ships have a relatively short useful life...salt water is rough on metal.

I suppose the upper limit would be when it’s possible to make an ocean-wide winch system and you can just hook barges to it and pull them across the ocean.

Just hook containers to it like cable-cars and move them across.

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