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It looks like a reasonable concept at a reasonable scale, perhaps good enough for a MVP. Here is an earlier short presentation. Their team right now seems too small to make it work, but they are recruiting, and they’re just starting. If they can make it work, or before they can make it work, it’s just a question of if the economics work out, which is of course questionable, but autonomous operation might help with that. No additional propulsion seems ambitious.
The market economics seem bizarre - intra European shipping of micro cargo ships? Cargo ships grew massive for efficiency reasons.
What tech are they actually proposing?
Is that what they do? Really?
Wow, sounds great!
Where is their group-selfie?
How about a route offshore from Somalia?
More NEWS news news news… OF THE FUTURE future future future…
The efficiency argument is relatively moot now though, if you don’t have to pay for your fuel. Now the more important thing is: how much cargo can we pull with this kite that we have, how expensive is our ship to make and operate, how much harbor time are we taking up maybe and so on, and what does that come to on a per container basis.
Don’t reckon they need a big team to get this proven.
They need to show an actual idea.
There’s an image of a blade somewhere in the sky near a wee boat. …
What is that?
Maybe they’ll only show us this amazing idea if we can prove we’re loaded rich and worthy enough to be potential investors
The business model and the system around it is the idea, and that would need to be proven. I guess you’d need experts in the shipping industry and ship building, market research and pilot projects to help with that. Physics tells us that kites can pull stuff so that doesn’t need to be proven, how to make it work is the challenge and for that they’d need more people I think.
In a way in a concept like this the difficulties are somewhat reversed: selling electricity is easy, selling cargo shipping is much more difficult; making electricity is difficult, pulling a ship is easier.
Another video, now with an animation: SUMMER OF PURPOSE 2021 SCIENCE GATE
Thanks @Windy_Skies
There was a lot more info there.
Still not sure how it overcomes all of the issues skysails faced in shipping.
But yes, they’ve done some modelling of a solution to the challenge.
I wish them all the best in this.
Hope they can bring more tech operational description to the forum soon…
Only took me a decade to get half good enough at that so far.
Kind of reminds me of self-driving cars. Sounded so good but there are always problems. I always think of a trash bag blowing across the road, and the car thinks it’s a person running thru traffic so it kills its passengers in a crash to avoid hitting the bag. In this case what happens to the hard airplane kite when they get to port? How do they dock? How do they remove the shipping containers? How do they launch the kite? And like Roddy says, how do they sell their services? How do they survive storms at sea? I say, show us one such boat with a predetermined route, then let’s see what we’ve got at that point. So easy to just wave your hands and say you will take over the world.
[Edit; the things I am writing here about drag coefficients is completely wrong, in hindsight. The large container vessel seems to win hands down in terms of drag per carried cargo mass]
Hi. It seems I missed this one, just gave it a look recently. Many of the ideas here line up with my own ideas. As this is a new project still, lets start by looking at the positives:
- Using kite propulsion and subsea foils should give them reltively high forward speed and less need for energy
- Autonomous operation should get the price down even for the relatively small scale
- The overall concept is relatively simple, [but combining three major untested technologies; kite ship propulsion, autonomous ships and large scale hydrofoil ship].
- Many smaller ships are easier and more efficient to manage than larger units, giving more available routes to choose from and less time for loading and unloading, and less requirements for harbour space
- Many units are less succeptive to accidents eg. Evergrande
- Advanced weather prediction allows them to plan a route to ensure wind from start to end destination.
- Autonomous ships are probably a lot easier than cars, as there is a lot of space at sea
My concerns, very briefly and initially:
- They need a backup motor to get the last mile to shore and back to sea
- Getting the vessel to plane will require a lot of pull, and low winds will cause the ship to sink again
- Small ships - history shows that larger ships are cheaper to operate, and infrastructure for large ships is already in place
- Three unproved concepts in one design
- Based in Munchen which is not close to the sea (actually you could not get further from the sea in Europe, more or less)
Overall I think the concept is one of the more interesting around for renewable ship transport. It will probably evolve if the basic design succeeds. It may find a niche transport route somewhere with consistent winds and where the cargo is less time critical, and where the customer is environmentally oriented. Such cargo could be eg. ore transport…
Doing some back of napkin chatgpt style calculations, assuming the large cargo ships have a drag force based on hull speed and underwater cross section, and lift based on the mass of the ship and cargo, the container ship would have a lift to drag of approx 0.3 - 0.4. Using foils should be able to achieve to a small fraction of that drag, so this is surely interesting, in terms of drag per kg transported cargo. Actually it would probably make a lot of sense to ditch the kite and make such a cargo vessel that was autonomous and on foils, but with a diesel engine
ChatGPT query:
use the ever given as an example and list width, depth of hull and mass of a fully loaded ship. Also state the drag coefficient at travel speed as well as travel speed.
Width (Beam):
58.8 meters.Depth of Hull (Draft):
15.7 meters (when fully loaded).Mass of Fully Loaded Ship (Displacement):
220,000–240,000 metric tons (including ship weight and cargo).Drag Coefficient (Cd):
For large container ships like the Ever Given, the drag coefficient is generally in the range of 0.8 to 1.0. A reasonable estimate for the Ever Given would be Cd ≈ 0.9.Travel Speed:
The typical cruising speed for the Ever Given is 22.8 knots (approximately 11.7 meters per second).Recap:
- Width: 58.8 meters
- Depth (Draft): 15.7 meters
- Mass (Displacement): 220,000–240,000 metric tons
- Drag Coefficient (Cd): ≈ 0.9
- Travel Speed: 22.8 knots (11.7 m/s)
Interestingly their web page [edit] shows an inflatable foil kite, while their patent shows a rigid kite
https://patents.google.com/patent/EP3995391B1/en
The patent claims include a vessel with:
- a kite
- subsea foils that can be adjusted for angle of attack or moment compensation
- the ship must carry cargo
This company is doing similar but no kite. It seems they also are maybe overreaching and should first go for diesel rather than hydrogen powered propulsion, to reap benefits of autonomy (lower cost) and foil ships (lower drag)
One would think, by this point, given the known advantages of hydrofoils, that we would see them in common use. One major disadvantage I recently read about is they increase the draft (required water depth) of any boat, by their protrusion below the level of the hull. This restricts their access to docks and wharfs.
I could also imagine problems with seaweed , fishing tackle, and debris getting caught in the hydrofoils and causing problems - maybe catastrophic crashes.
While I like the idea of small autonomous craft for shipping, as Tallak points out, bigger ships are more efficient. That’s why everyone uses them, for God’s sake.
Hello? What about hydrofoils for large ships? Oh, then you’d have to dredge all the harbors that much deeper?
The other major factor people from areas where trust and integrity are the norm seldom grasp, is piracy. In areas where violence and corruption are the norm, so is piracy. The reason we have navies around the world was in large part to protect shipping. The U.S. navy was started in response to pirates from Morocco etc., stealing ships, and using them in kidnapping raids to steal people from coastal towns in Europe, to sell as slaves in Northern Africa. One seldom hears about this in today’s world, but by the same token, I would say small autonomous craft full of valuable cargo might be vulnerable to people of low integrity, with too much time on their hands, tempted to just steal the cargo.
Wonderful project for an engineer, but I have serious doubts about scaling issues. We all know Froude scaling has to be applied when weight and hydro/aerodynamic are involved (same as for kite). This ship could work at small scale from known ships, but going to greater scale, you would have to go faster or increase the foil size in proportion. The issue is the wind is not going faster (or marginally) when going at scale, so you can’t keep up with the speed needed.
OTOH they are less than 200 meters from the river through the city and there are 3 big lakes within 30 kilometers of the city.
You could imagine something like a rowboat with lots of oars on either side, but now the oars are foils. In shallow waters and when moving slowly the oars are above the water.
I think a beautiful aspect of this idea is, as a fully autonomous vessel, the incentive to scale is much less… why must they scale? I guess one reason is to overcome waves and access high altitude wind. But the wind gradient at sea does bot really give too much over a certain moderate altitude [1000 m altitude?].
Well I do se a clear uptick in use of foils for recreational use in kite, windsurf and wingfoiling, as well as sail dinghys. And now also downwind paddleboarding and wavesurfing. Then you have the larger sailboats used in races, no longer really hobby scale. Then you have the foiled motor boats for leisure. None of these were on the market 15 years ago (?).
This does look a lot like technology maturing, why should it not grow to container ship scale? [well I realize, some of the reasons you mention like debris].
For cargo, the scale must go down for technology to have an evolution path, and this adds a requirement of autonomy because of cost. But hydrofoils and autonomy are both emerging technologies, so I dont see a showstopper anywhere saying that these technologies would not eventually become mature enough that it would make sense to combine them.
You did not have small foiling boats 15 years ago, but you had big ones Boeing 929 Jetfoil - Wikipedia.
I thought they were discontinued but just noticed, one was produced in 2020 VESSEL REVIEW | Seven Island Yui – New hydrofoil passenger vessel enters service between Tokyo and Oshima island
They are expensive to maintain, so it makes sense for passengers, not for heavy cargo.
I would argue that the issues with high speed could be alleviated by having bigger lifting surface foils. This would take away any arguments regarding extra aerodynamic drag, and possibly also energy necessary to get into planing.
High maintenance cost seems to be a real issue, I don’t think it can be easily alleviated. It sould get worse in smaller scale.
Also interesting that debris doesn’t seem to have any historic mention as a major issue.
The issue with low efficiency gas turbine engines is also probably a real issue as the method to generate propulsion at high speed is probably less efficient than those used for low speed, and the system must be able to operate in a wider speed region (in particular very high thrust at zero or low speed in water, then efficiently at very high speed during cruise).
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ChatGPT says
Despite the fact that hydrofoils, like the Kawasaki Jetfoil, experience less drag than submerged hull designs at higher speeds, their overall fuel efficiency was not as favorable for several reasons:
1. High-Speed Operation
- Hydrofoils are designed to lift the hull out of the water at high speeds to reduce drag. However, achieving and maintaining these high speeds requires significant power. The Jetfoil used powerful gas turbine engines (adapted from aircraft technology), which were fuel-intensive to operate. While hydrofoils reduce drag once they reach planing speeds, they require large amounts of fuel to accelerate to the point where the foils can fully lift the hull out of the water.
2. Gas Turbine Engines
- The Kawasaki Jetfoil was powered by gas turbine engines, which are more common in aircraft than marine vessels. These engines are known for their high power output but are less fuel-efficient than diesel engines typically used in marine transport. Gas turbines are optimized for performance and speed, but they tend to have lower thermal efficiency and consume more fuel, especially during non-optimal operational ranges (i.e., at slower speeds).
3. Hydrodynamic and Aerodynamic Drag at High Speeds
- While hydrofoils do reduce hydrodynamic drag by lifting the hull out of the water, aerodynamic drag becomes more significant at higher speeds. The Jetfoil’s high-speed operation led to increased air resistance, especially in the open ocean, which required more engine power and thus more fuel consumption to maintain speed.
4. Complexity of the Mechanism
- The mechanism that allows the hull to rise and operate on foils is mechanically complex and requires precise control systems, which add weight and drag. Additionally, the maintenance of the foils themselves could affect performance over time, and any degradation could lead to less-than-optimal operation, further reducing fuel efficiency.
5. Operational Conditions
- Hydrofoils, including the Jetfoil, operate optimally in calm seas. Rough seas increase the strain on the system, causing more drag and requiring additional power to maintain stability and speed. The fuel efficiency would drop in less-than-ideal conditions, which are common in open waters.
6. Fuel Costs vs. Passenger Capacity
- The Jetfoil’s primary advantage was speed, but its relatively small passenger capacity compared to larger ferries meant that fuel costs per passenger were much higher. Traditional ferries, while slower, could carry more passengers or cargo per trip, making them more economical on a per-passenger basis despite higher drag from their submerged hulls.
Conclusion:
- While hydrofoils reduce water drag at high speeds, the high power demands of reaching and maintaining those speeds, the use of fuel-hungry gas turbine engines, and increased air drag all contributed to the Kawasaki Jetfoil’s poor fuel efficiency. This, combined with operational costs and competition from more efficient marine and land transport options, led to its eventual discontinuation.