Computer-Controlled Cargo Sailing Vessels Go Slow, Frugal 210
An anonymous reader writes "Big container ships are taking it very slow these days, cruising at 10 knots instead of their usual 26 knots, to save fuel. This is actually slower than sailing freighters traveled a hundred years ago. The 1902 German Preussen, the largest sailing ship ever built, traveled between Hamburg (Germany) and Iquique (Chile): the best average speed over a one way trip was 13.7 knots. Sailing boats need a large and costly crew, but they can also be controlled by computers. Automated sail handling was introduced already one century ago. In 2006 it was taken to the extreme by the Maltese Falcon, which can be operated by one man at the touch of a button. We have computer-controlled windmills, why not computer-controlled sailing cargo vessels?"
Sails for container ships, slashdot 2007 (Score:3, Informative)
There's already some good ideas about putting sails on container ships (that don't get in the way of loading, like masts would do)
See slashdot from 2007:
http://hardware.slashdot.org/article.pl?sid=07/11/26/1925210 [slashdot.org]
Re:Weight (Score:3, Informative)
Re:Weight (Score:5, Informative)
I don't expect sail power would scale to the size of modern container ships.
Sure, a sail array may not be the best solution for getting a container ship underway from a standstill, but once the ship reaches open ocean, and a course is set, sails can be used to replace some of the engines' thrust, saving fuel.
Considering that container ships consume 100-400 metric tons of fuel per day, even a 5-10% savings would be pretty damn significant.
(Of course, 100-400 is a very broad range - the 4,250-TEU Arafura consumes ~65 MT / day, while the 11,000-TEU Emma Maersk chows down on 350 MT per day, so yeah, YMMV).
Marine Diesel is about $ 420-450 per metric ton [bunkerworld.com] right now.
As an intellectual exercise, let's take a 6,000-TEU ship consuming 100 MT/day, making the Shanghai-Long Beach run at express speed (15 days), and let's take the cost of MDO at $ 435.00 per metric ton.
At 5% savings, the sail array will save $ 2,175 / day. Multiply by 15 days = $ 32,625 saved per trip.
To put this into even more of a perspective, the average lifetime of a container ship is 27 years. Assume it's running 75% of the year. (27*365)-25% = 7,391 days. Take $ 2,125 saved per day * 7,391 days = $ 15,705,875 saved.
Is $ 15.7 million enough to pay for the sail array + computers? Seems like it to me.
Re:Weight (Score:3, Informative)
That's because there's a shipping glut. (Score:5, Informative)
Cargo ship speeds go up and down with the costs of ship charter and fuel, and with the demands of customers. Read "The Box" [amazon.com], a history of shipping containers and the ships that move them.
Right now, the Baltic Dry Index is down to where it was around 2000, after a huge 5x spike last year. So there's a huge glut of available container ship capacity, charters are cheap, and freight rates are way down. So operators have to optimize for low cost at the expense of speed and throughput.
There's also no big demand for speed from the customers. Much of what's being shipped is going into storage anyway. Unsold cars are piling up near ports [bloggingstocks.com], filling up storage and spilling over into rented parking lots. That's presumably happening with containerized commodities too, in cases where the buyer can't just cancel the order.
It's one of those things that happens in a depression.
Need sailors to vette sea stories (Score:5, Informative)
Some moron did the article. A moron who has never been to sea, obviously.
I challenge any weekend warrior to find me any cargo ships that make 26 knots, anywhere, today, last year, or last decade. In an emergency, a FEW of them might make that kind of speed, but they can't sustain it day after day, like naval ships can. A blown boiler is sure to ruin anyone's day.
Warships didn't even make a habit of running that fast, 30 years ago, when fuel was cheap. The first time I crossed the Atlantic, I asked "How long?" like any kid in the back seat of a car, on a long trip.
The answer: "We can be in Portugal in 5 days, if we burn x gallons per minute, or we can be there in 11 days, if we burn y gallons per minute. So, we'll be there in 11 days."
The destroyer I served on was capable of doing about 35 knots (officialy 30+) and we could catch ANY commercial freighter, tanker, container ship, or whatever.
IF, and I say IF, cargo ships were capable of 26 knots as the article says, THEN, they would be transiting the hi danger piracy zones at that speed, and the pirates wouldn't be catching them.
Many 19th century sailing ships could routinely take most commercial traffic in a race, even BEFORE companies started slowing down to conserve fuel. Revisit the sailing times for ships such as the Cutty Sark, then look at the sailing times for today's tankers and container ships. Real sailing times, not "best case scenario with favorable winds" sailing times. ;)
Your intution deceives you. (Score:3, Informative)
You can certainly move forward using the energy that is pushing your working surface sideways. A sailboat on a tack moves upwind, because the sail is pushed downwind (which is counterproductive), but it is pushed even harder sideways across the wind. Windmill blades move sideways across the wind at all times; think of the blades as seperate sails, on an eternal upwind tack.
Designing a windmill-driving-a-turbine contraption to make headway upwind poses no impossible hurdle. Whether enough efficiency can be obtained in practice is a different matter. Carts with windmill powered wheels that move directly upwind have been constructed by countless physics students, including me.
Re:economics and variability (Score:1, Informative)
>>Apparently she's now a restaurant ship in New York.
Philadelphia
Re:Need sailors to vette sea stories (Score:4, Informative)
I have personally witnessed a large fishing vessel actually outrun a USCG vessel on fishieries enforcement (which was pretty funny, but it couldn't outrun the helo).
No great achievement there. Check out:
http://www.solarnavigator.net/hull_speed.htm [solarnavigator.net]
Or google for similar.
In summary, due to various wave displacement thingies (err, hydrodynamics) a ship forms two waves, one at the front and one at the back. Turns out the power required to go more than X of those wavelengths per minute scales by some crazy huge polynomial. So thats the qualitative explanation.
For a simple displacement hull, there's no way to get a USCG 100 foot boat above maybe 15 knots, whereas a 300 foot fishing boat can easily coast along at 25 knots or so. Maybe the USCG could plane some, and go somewhat faster, maybe, at immense fuel costs.
It's always kind of funny how "sailor-types" don't know these formulas, and the few that do, don't know landlubbers know them, so you get hilarious claims from some sailors about aircraft carriers that go 75 knots, but that's "top sekret info".
Obviously this does not apply to hydroplaning hulls that skip or "plane" across the surface of the water, or hydrofoils, but most "big boats" are simple displacement hulls... A hydrofoil nuclear powered aircraft carrier would be impressive. Usually those hydroplaning boats don't handle rough seas very well and don't have very long range. So simply send the robo-shipper thru storms and rough seas that it can shrug off, but would utterly swamp an inflatable or a pontoon boat or whatever it is pirates use, and floor it so the tiny pirate boats can't keep up in the long run anyway.
As a side note it's even funnier when a boat tries to outrun a navy vessel, given how fast bullets, ship to ship missiles, and torpedos move. USCG has helicopters, USN has supersonic aircraft with harpoon missiles, or barely subsonic cruise missiles....
Re:collision avoidance (Score:3, Informative)
We're not talking about unmanned ships, just ships with sails which are adjusted by machines instead of dozens of sailors.
is. The captain turns the steering wheel and a bunch of motors do the furling/unfurling.
Re:Financial fail ... (Score:2, Informative)
You see, his calculations are based on fuel costs (not on hard $$$). And those costs grow in accord with interest rates (you know fuel is that kind of commodity).
So his calculations in that regard are alright (more or less).
The Moshulu is anchored in Philadelphia forever. (Score:1, Informative)
It has good steaks and a fun Margarita night.