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?"
economics and variability (Score:4, Insightful)
The bean-counters decided it was better to operate off a relatively fixed cost like fuel and have a dependable schedule. The whole story of the 20th century has been "Yeah, you could do this or that but it's just simpler and cheaper to use fossil fuels." Environmentalism won't drive alternative fuels, economics will. If it becomes cheaper to use sail, we'll go back to sail. The cost of fuel will only rise from this point, peak oil is here, so the economics we need for sail should be here now.
Re:economics and variability (Score:4, Insightful)
The other story of the 20th Century was "Just-In-Time", which meant reserves and stockpiles have been kept as low as feasible. That would be another factor limiting acceptance of sail - we'd need larger stockpiles to ride out any delays. Honestly though, with satellite imaging, and computer control - there's no real reason sail travel should be any less controllable and predictable than using fossil fuels. And at the speeds involved, there wouldn't even need to be any major code to do image processing and interpretation on the ship itself (though with the computer needed to handle the rigging, and the need to monitor against potential collisions, should be enough to actually do the planning on ship... but coordination would be better from a central site and general directions relayed via satellite.)
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:economics and variability (Score:5, Interesting)
The unreliability of sail is an issue, though. I think we'll see "hybrid" shipping becoming more common -- kite sailing when the wind is favorable (or perhaps kite-assisted), fossil fuels when it is not. This will reduce costs & environmental impact, a nice combo.
Here [slashdot.org]'s a discussion we had previously on kite-assisted shipping.
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i would prefer to have nuclear used in the ocean where a limitless supply of plasma coolant is available and has the option to "eject the warp core" when things go tits up.
pirates (Score:2)
I wouldn't want that if, for no other reason, due to the piracy off of Somalia. It would be far too easy for them to simply steal the nuclear fuel if they were nuclear powered.
Heck, there's concern about even arming the crews because they're afraid this would just encourage pirates to steal the weapons.
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Actually, in the long run it'd be a very good thing if a band of Somali pirates got their hands on some nuke fuel.
The pirates themselves don't have the capability to convert it into anything more than a dirty bomb.
The pirates could sell the material to the terrorist organization du jour. They might be able to make a slightly more effective dirty bomb out of it.
That's if the focused attention from the bulk of the western world hasn't given Somalia a new coastline that is twenty miles further inland than the
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No shit, Sherlock (Score:2)
Re:economics and variability (Score:5, Insightful)
Its not just about fixed scheduling, its about weight and economies of scale. Sails are no longer viable with the size of the ships transporting cargo. The smallest ship I've dealth with holds 300 20ft containers with an avg weight of ~30,000 lbs. Some can be loaded with over 200 million pounds of cargo. I don't even think we have the materials developed to make sails for those physically possible.
The only practical application of sails for cargo ships is augmenting the engine, which we've seen before here on slashdot (too lazy to find the link).
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Sails are no longer viable with the size of the ships transporting cargo.
Maybe not economically viable, but it certainly seems physically possible [slashdot.org].
Wingsails, not traditional sails (Score:3, Insightful)
Sails, whether made of traditional textile material or something more newfangled will probably not power those container ships moving all that crap from far-east to west. Wingsails on the other hand could be used for generating a sizeable portion of the needed thrust. They also have the advantage of being much easier to automate, give more thrust per surface unit and give better handling. Rigid wingsails can be covered with photovoltaics giving even more 'free' power in the right circumstances.
Point your fa
Re:economics and variability (Score:5, Insightful)
Dependable schedules are one reason, the other big reason is that sails interfere with loading and unloading the boat.
Modern shipping extensively uses cargo containers that are rapidly loaded and unloaded using cranes. This advance has drastically lowered the per-unit costs of shipping freight in the last half-century (check out the book "The Box" [amazon.com] for more details).
If adding sails makes it difficult to use a crane to unload containers from the deck of a boat (likely, imo), then it would make the per-unit cost of shipping skyrocket.
Re:economics and variability (Score:4, Interesting)
The bean-counters decided it was better to operate off a relatively fixed cost like fuel and have a dependable schedule. The whole story of the 20th century has been "Yeah, you could do this or that but it's just simpler and cheaper to use fossil fuels." Environmentalism won't drive alternative fuels, economics will. If it becomes cheaper to use sail, we'll go back to sail. The cost of fuel will only rise from this point, peak oil is here, so the economics we need for sail should be here now.
Go read Eric Newby's The Last Grain Race [amazon.com]. It's a great book, but it's also relevant: it's the story of the author's trip round the world as a sailhand on the last commercial sailing fleet, in 1938.
His ship, the Moshulu [wikipedia.org], was one of a fleet of grain freighters that sailed from Europe to Australia, loaded grain there, and then sailed back again. They occupied a particular peculiar economic niche; being specialised sailing ships and technically quite simple, they had very fixed costs. As a result, it was feasible for them to stay in port in Australia for several months while small loads of grain trickled in from the farmers. Steamers were unable to do this, as they needed to be constantly trading to offset the fixed costs. Instead, they'd have to rely on warehousing, which would eat into profits.
It also helped that the Moshulu's owners didn't spend much on maintenance; some of Newby's descriptions are terrifying.
On Newby's trip, she made the voyage from Belfast, Ireland to Port Lincoln, Australia in 82 days, which is pretty good. She could do about 17 knots. Apparently she's now a restaurant ship in New York.
Read his book --- it's fantastic.
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It isn't just cheaper because of fossil fuels. Bigger always meant better in the shipping industry. The average lifetime of a cargo ship is 30 years. Small boats last, on average, half that. Large cargo ships are easily recycled. They are 80% steel. Small cargo ships are fiberglass or wood. Cargo ships very rarely sink. If they do, they make excellent reefs. It takes very little hull damage, and smaller storms, to sink small boats. Fiberglass sucks for reefs and wood decays to quickly.
USV (Score:3, Interesting)
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Computer, if you don't open that exit hatch this moment, I shall go straight to your major data banks with a very large axe and give you a reprogramming you'll never forget. Is that clear?
Re:USV (Score:5, Funny)
I'm sorry Dave, I can't let you do that.
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Re:USV (Score:4, Insightful)
"Dear mister pirate. This ship is equipped with 'ROMG'. This stands for remote operatable machine guns.
Way too messy. If the computer had the ability to control the ventilation system and hatch locks, the computer could lock them inside. That is when the nerve agent would be released. Post the video of those bastard's slow, agonizing death on YouTube. That would make them think twice about jacking ships.
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Unfortunately, it would be pretty illegal.
Now, if you DID lock them in, and then proceeded to finish one's several-week journey... well, I hope they brought food and water with them. It'd be like Survivor, in some dingy corridors, with rifles and angry pirates.
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Less romantically, piracy was the origin of the idea of offenses against all nations, not just particular powers, as well as the classical example, long before the war crimes trials at the end of WWII.
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Yep, exactly what I was thinking ...
A good fire suppression system would make quick work of intruders without the mess.
Halon or CO2 would be my choice.
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"I'm sorry, Abdul, I can't do that." (Score:2)
'And don't give me any of that 'first directive' nonsense, this ship is Designed For Windows 7 (tm)"
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And thus, The Pirate Robot Wars of the early 21st century was born. The technology used to control ships from occasional satellite linkups was made fully autonomous (shore-to-shore 'bots) by 2012. Soon after, pirates purchased the technology to also hijack a ship remotely using a combination of machines, from nimble boats to wall-crawling, hole-drilling robots, to swarms of machine-controlling "infestors" that could determine a ship's design and take the best course of action for overriding the original
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Or sail with a remote pilot? I mean we have planes that can be controlled by a pilot on the ground... why not ships?
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Think of the surprise that the Somali pirates would get if they got on board and found no one. Just a sailboat with a locked server room.
"Just what do you think you're doing, pirate?"
Re:USV (Score:4, Funny)
It also means the robot guards can just be programmed to kill anything that moves, without having to bother trying to protect a crew.
'Course, that might mean a massacre at the port if there's a problem shutting down the guards...
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'Course, that might mean a massacre at the port if there's a problem shutting down the guards...
Wouln't be a problem in a world where everyone drinks Brawndo: the robot guards would just shoot themselves!
Too far fetched? Just look at the guy working next to you once cubicle over and think for a bit. Then ask him if he's getting enough electrolytes from his "energy drink". If the answer is "Yes", ask him if he likes sex. Or whether he likes money.
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... ask him if he likes sex. Or whether he likes money.
Hmm. Might cause more confusion than I want in my office.
Re:USV (Score:4, Funny)
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I am against funding for anti-pirate robots unless we can manage to work in ninjas somehow. And zombies.
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An automated machine gun will kill a ninja just as dead as a pirate.
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Robot wars on the high sea (Score:2)
Heh heh heh... just wait until those grappling hooks are on your hull and desperate armed pirate robots are scurrying up the rope ladders.
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RIAA agents would just shoot their mouths off, then shoot themselves in the foot.
K.
Re:USV (Score:4, Funny)
Think of the surprise that the Somali pirates would get if they got on board and found no one.
Taking this one step further.
Imagine a group of Somali pirates boarding a cargo ship. They arrive on the bridge to discover it's empty. The doors to the bridge slam shut and lock behind them. The room fills with sevoflurane gas, [wikipedia.org] rendering the pirates unconscious.
When the pirates regain consciousness, they find themselves in a holding cell. This holding cell is surrounded by other holding cells filled with other Somali pirates who fell for they same trap they did. This ship isn't a cargo ship at all. Its a trap designed to clean up the seas around Somalia.
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Still a rather expensive way to get rid of pirates - after all it means you need $$$$$$$$ for a huge ship, that may or may not attract pirates.
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Just bring back Q Ships.
A deck mounted GAU-8 Avenger would be a good start.
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Seriously, you are right of-course, today humanity can devise much more effective measures than gassing someone, who might otherwise have a gas-mask on them. [wikipedia.org]
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Security? (Score:3, Funny)
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The current pirate problem is caused by pirates who don't actually have any use for the ship's cargo: They just hold it for ransom. A computer-controlled ship with no way to override would be less useful to them: They could destroy it, but they can't hold it up or delay it significantly.
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And it's much easier to have a policy of never paying the ransom if there are no human hostages.
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Another bonus: It makes 'just blow them up' a much more acceptable option.
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The ship did have a safe room according to news reports. That's why the pirates took only the captain.
150 years ago, British Foreign Secretary Palmerston observed that "Taking a wasps' nest... is more effective than catching the wasps one by one". - http://news.bbc.co.uk/2/hi/africa/7991512.stm [bbc.co.uk]
Also consider Julius Caesar's experience being taken by pirates. There was a politician who carried out his promise.
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If it has a propulsion system, it can be delayed- most likely at a very low cost.
Sails: Grapeshot
Prop: Cables/Nets
Either: Toss a cable to one side of the ship and tow it in circles.
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A ship could use an impeller instead of a regular propeller to make the cables / nets option a lot more difficult.
Towing the ship in circles wouldn't be very difficult, until the ships computers start compensating, raise the alarm and throttle up a bit. As far as I know, the Somali pirates mostly use small boats, not impressively powerful towing boats.
Maybe they should just start using some flags on autonomous ships indicating they are equipped with automatic defense systems.
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That's because they're NOT pirates, except in the most strict of senses (Meaning in the verb sense of the word "To attack and rob (a ship at sea)").
These people are KIDNAPPERS. They hold the CREW hostage until they're paid off.. In most cases, they have absolutely no use for the cargo, as you mentioned above. People that hold other people captive until they're paid off are NOT pirates, they're kidnappers, plain and simple.
Stop calling these people "Pirates" (Yaar!) and start calling them "Kidnappers", and
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That's because they're NOT pirates, except in the most strict of senses (Meaning in the verb sense of the word "To attack and rob (a ship at sea)").
These people are KIDNAPPERS. They hold the CREW hostage until they're paid off.
You also got it wrong. Everyone knows pirates download mp3s off the internet. And warez too.
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here [slashdot.org] is the answer
Windmill != Ship (Score:4, Funny)
INAM (I'm Not A Miller) and I'm not up-to-date with the tech, but as far as I'm aware windmills can't plough into harbours destroying themselves and their cargo, potentially killing lots of people at the same time.
Re:Windmill != Ship (Score:5, Insightful)
Neither computers nor crews pilot vessels into harbours. Harbour pilots do.
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Computers could be used to navigate in the open ocean, and harbor pilots [wikipedia.org] could continue to navigate through dangerous waters the same way they have for centuries.
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http://www.youtube.com/watch?v=NLInrjUtFGI [youtube.com]
true- it wasn't a harbor-- but I still ain't gonna sit underneath this puppy
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Wow, are you behind the times. You should see the newest generation of windmills...
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]
Energy out of the atmosphere (Score:2)
I've often wondered if we converted all our power generation to wind, whether we'd replace global warming with rapid global cooling? After all, wind is really just presure differentials caused by asymmetric heating.
Is there a chance that by trying to save the planet, we replace a disaster that turns half the world in to a desert with a disaster that places northern Europe under a kilometer of ice?
Simon
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I can't say I follow. Heat creates the wind. Using that wind doesn't cause that heating to never take place. It certainly doesn't remove any energy from the system as a whole. Perhaps I am missing something...
(I love having to wait 5 minutes between posts).
I think the more immediate concern. . . (Score:2)
I think the more immediate concern would be the potential impact on wildlife from having massive wind farms. Would large arrays of wind turbines potentially have any adverse affects on bird migrations, or even just birds in general? Or bats? What sort of injury/death risk do wind turbines pose for birds and bats?
It seems like nothing man can do can have zero impact on the environment, ultimately.
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This may not count as zero impact in the short term, but ...
As kids we visited the atomic museum (I forget the name) in Los Alamos, NM. The had some sort of simulator where you could turn dials corresponding to different human activities. The output was a list of various things such as pollution, hunger, population, and so on. AT least a dozen. All of them had a red, yellow, or green lights. A few had numerical output.
So we started turning this knob, then that. Lights would go back and forth between
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Would large arrays of wind turbines potentially have any adverse affects on bird migrations, or even just birds in general?
In the UK, the Royal Society for the Protection of Birds [rspb.org.uk] reviews applications for permission to build wind farms, and 93% of the time, they see no problems. They do object to 7% of the applications.
Wind power advocates often point out that more birds are killed by cats and by flying into windows (by several orders of magnitude) than by wind farms. Here's a comparison from How Stuff Works that shows wind farms killing tens of thousands of birds as compared with cars, windows, cats, and other bird risks kil
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Missing linky from previous post: http://science.howstuffworks.com/wind-turbine-kill-birds.htm/printable [howstuffworks.com]
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This is something I've been wondering about for the last ten years or so, but I've never been able to get much an answer out of people in the know. It does seem naive to suppose that the world is just so big, nothing we do will have an impact.
The closest I've seen to an acknowledgement of these issues was from Arthur C Clarke. He speculated that as the byproduct of energy conversion is heat, these renewable energy sources will be dumping extra heat into the atmosphere.
In a way, it's already hapenning (Score:5, Interesting)
SkySail: using the a computer controlled parasail to improve fuel efficiency. Article http://www.popularmechanics.com/outdoors/boating/4235055.html [popularmechanics.com]
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For large ships, there's also software than can plan the optimal passage by simulating and optimizing routes for given arrival times while minimizing fuel consumption and avoiding weather damage [jeppesen.com].
Automation is overrated (Score:2)
...why not computer controlled sailing cargo vessels?"
They are computer controlled to a degree but the reason they aren't unmanned has to do with the fact that navigating a boat is a remarkably difficult endeavor and our technology available to the task is both extremely expensive and insufficiently flexible to the wide variety of sea conditions and probably unreliable in such a hostile operating environment. That of course presumes it is possible at all to do it safely which is highly unlikely. Add in the fact that unmanned vessels would be remarkably attr
storms (Score:2)
Everyone's talking about pirates. Seems to me that storms are more likely... the longer you are at sea.
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. ;)
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A blown boiler is sure to ruin anyone's day.
While I agree that most merchant ships can't sustain 26 knots. I don't think many of them are steam powered anymore. They mostly use low speed diesel engines, such as those manufactured by Wartsila. [wartsila.com]
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You are right, the article is ignorant. But I disagree w/some of your assertions.
Many merships can exceed 30KTS. And so can many large fishing vessels and support craft (by large, I'm talking container ship sized canning factories, etc). They choose the speed depending upon economics.
Yes, a tin can should be able to catch any mership (given enough time). I have personally witnessed a large fishing vessel actually outrun a USCG vessel on fishieries enforcement (which was pretty funny, but it couldn't out
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:Robo-sailor (Score:5, Funny)
Yeah... Let's send robot ships out there to travel to a port and then wonder WTF happened when it doesn't arrive... Did the scurvy pirates get it or did it drift off course or did it sink?
If only they could invent some type of Global Positioning System. I can see it now... you would need a couple dozen or so satellites to ensure coverage over the planet. They would broadcast some type of signal. Then all you would need is some type of devices to read the signal from two or three of these satellites to get a 2D or 3D positioning.
*runs off to patent office*
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Yeah... Let's send robot ships out there to travel to a port and then wonder WTF happened when it doesn't arrive... Did the scurvy pirates get it or did it drift off course or did it sink?
If only they could invent some type of Global Positioning System. I can see it now... you would need a couple dozen or so satellites to ensure coverage over the planet. They would broadcast some type of signal. Then all you would need is some type of devices to read the signal from two or three of these satellites to get a 2D or 3D positioning.
*runs off to patent office*
Uh, huh. And the ship could read this, and then radio its position to its owners. Except... what happens when the pirates, y'know, switch off the little radio transponder thingy?
GPS != global LoJack.
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Speed from Sail power is proportional to drag, not weight.
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.
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Financial fail ... (Score:5, Insightful)
Those numbers only work when your personal interest rate is 0, which is rarely the case.
Realistically, you need to adjust for the time value of money [wikipedia.org]. ($100 now is worth more than $100 27 years from now, as I could make interest off of it)
So, if we assume that the savings are every month, with a 3% interest rate compounded monthly, we'd have (12x27) payments of about $49,617 each with 0.25% interest per period:
PV(A) = (49_617 / 0.0025) * ( 1 - (1 / 1.0025**(12*27) ) )
Which works out to just over $11 million. The install cost would have to be less than this, to deal with the reoccurring costs of maintenance of the new system.
Oh ... and if the interest rate were 6%? That $11mil estimate would be cut to under $8mil, or about 1/2 of your estimate. In a good market where we might be able to make 18% return, over 27 years, it's worth less than $3.3M.
Now, I don't know how much container ships cost, but if I can add another ship and move more containers, that may give me a better benefit for the same cost.
(and, I know you later said that the actual savings were higher -- but the point is, you should _never_ just multiply reoccurring costs or savings by the number of periods to get the equivalent present value, especially for periods of years.)
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Great comment, should be up-modded.
On the other hand, you forgot to account for sail array maintenance costs, additional crew training, and the extra risk of sail failure in the event of harsh weather - not that I have much of an idea of sailing, but the investment is not completely risk-free. Most container ships don't have sails on them, and diesel engine expertise is much more widely found than sail array expertise; this makes maintenance harder that it could be.
There is bound to be a first-mover risk (a
Scaling of ships (Score:2)
It isn't quite as simple as that because the sail supports increase in weight as rather mo
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Hmm.. does it have to be a SAIL boat? (Score:3, Interesting)
can it be a big mother mounted windmill and an electric motor???
bonus being- no tacking into the wind-- rotate the damn windmill and head on into it...
it's not perpetual motion- energy is being added (Score:2)
the wind is adding energy to the situation
if you had a very efficient windmill, and a very aerodynamic & hydrodynamic boat-- why is it impossible?
picture a pulley mounted on the sea floor, through which a rope connects two boats, both 100 miles downwind from the pulley
BOTH are of equal mass.
one boat has a large sail and is angled to go with the wind-away from the pulley,
the other boat is very aerodynamic and pointed into the wind
you are suggesting the aerodynamic boat won't move into the wind?
imagine t
Re:it's not perpetual motion- energy is being adde (Score:5, Insightful)
You can not move forward by capturing energy being used to push you backwards. To move forward would require more than 100% of the energy that you're capturing. It doesn't work.
Re: (Score:2)
What you state is true, but, as the other guy said, it doesn't apply in this situation because you're not capturing the energy being used to push you backwards. Remember, the velocity of the water need not be the velocity of the wind; in fact, it almost never is. Also remember the difference between apparent wind [wikipedia.org] and true wind. The apparent wind is what determines the force on the blades or the sail, not the true wind, except where the true wind = apparent wind which would be the case for a wind turbine
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 eter
Re: (Score:2)
Um, your point being?
You mean with a force applied endlessly something will accelerate endlessly? Truly that breaks every known law of physics...er, no wait, I lied, it is exactly what classical mechanics would predict!
In actuality the drag would increase as the speed increases which would balance out the propelling force. But if there was no drag, why wouldn't it accelerate for as long as the wind was blowing? Would you expect it to stop accelerating even though there is still an overall force on it?
Re: (Score:2)
Sailboats do all sorts of nonintuitive things that are in fact quite compatible with physics... like sailing downwind faster than the wind, and sailing upwind. There's no reason a boat powered by a wind turbine can't go directly upwind.
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This is false, you can not sail upwind using traditionals sails but using wind turbines it is certainly feasible. And why would moving forward require more then 100% of the energy captured? As long as the wind is pushing hard enough, it will move forward. The energy provided by the wind just has to exceed the resistance of the boat to move (friction). And then, the energy needed to move the boat against the wind does not increase linearly with the wind speed.
Imagine a boat with a windmill on it. Imagin
Re: (Score:2)
Well, you're right and wrong. Actually, it's entirely possible to put a VAWT on top of a ship and move it. However, it's somewhat unlikely that you could get efficiency over just having a sail, meaning that the amount of energy you'd get from the wind would be less, which in turn would mean that you would not be able to sail as many points from the wind as a real sailing ship. Basically, you would pretty much always have to follow the winds. It's not impossible to construct a route like that, though.
Re: (Score:2)
For things like bulk shipments of ore, which are enormously heavy and bulky; but not all that valuable per ton and have reasonably predictable demand levels, a slower and cheaper shipping method could be quite useful. I dou