FYI, the main innovations of these kite sails compared to traditional sailing ships are that it doesn’t need masts that get in the way of cargo handling and that it requires fewer crew. In other words, it’s not faster or anything; it’s just cheaper.
You also need vastly less sail area and the things are more reliable because wind gets quite a bit stronger and reliable at 100-300 metres up. The system actually isn’t new. AFAIU main reason for it not getting wide-spread adoption is that shipping lines, not ship owners, pay for fuel.
Modern cargo ships are so huge traditional sails wouldn’t provide enough force to push them around. Neither will these kites, mind you. But, supplemental energy will still be a bonus, and a kite can reach higher and sit in faster, more stable winds.
Modern cargo ships are so huge traditional sails wouldn’t provide enough force to push them around.
Believe it or not, “proportionality” is a thing. You make the ship bigger, you make the sails bigger to match. Simple! Granted, previously, making sails bigger was limited by the weight of the things when hoisted by men operating manual winches, but now we’ve got motors now to solve that, and higher strength-to-weight ratio materials, too.
Point is: I maintain that, in principle, you could make a post-Panamax sailing ship – even a traditional fully-rigged one – if you really wanted to, and it would be capable of sailing at hull speed on wind power alone. It’s just that they don’t want to for reasons unrelated to technical feasibility.
You’re assuming everything scales linearly, which is not necessarily accurate. The square-cube law rains on many people’s parades.
It would be really interesting to see a fully rigged ship with dozens of sails where the rigging was pulled by motors and controlled by computers rather than humans. It would also be interesting to see what they could do with modern materials. Nylon sails, carbon fibre masts, steel lines, etc.
Having said that, I would bet that a real modern cargo ship would probably use fancy solid wing-style sails.
You underestimate the force of wetted surface area resistance. The sail area needed to move a modern cargo ship at the snail’s pace of old sailing ships would be unmanageably large. You simply couldn’t hold enough sail area to get them near their current speeds. These hybrid sail concepts are nice, but all they do is save some fuel.
So, I got that information from a different Lemmy comment, and on the spur of your contradiction I went looking myself. My search results are flooded with mostly useless news articles (they went to tell stories, not relay technical information). Regardless, the most ambitious claim I’ve seen is to reduce emissions by up to 90% for a ship design that can’t handle shipping containers and is about 1/4 the size of the largest ships being produced today.
Don’t get me wrong, I want this to happen. In fact, I would ban carbon-fuel shipping today, if I could make it happen. That being said, I don’t think we’ll ever get back to 100% wind power.
