Wind Powered Freighters Return

thatoneguyfromphoeni writes "It appears that sails could return to the ocean's freighters soon. Newsweek is reporting on a technology to assist with cross-ocean travel. From the article: 'SkySails' system consists of an enormous towing kite and navigation software that can map the best route between two points for maximum wind efficiency. In development for more than four years, the system costs from roughly $380,000 to $3.2 million, depending on the size of the ship it's pulling. SkySails claims it will save one third of fuel costs.'"

Comments

Welcome to the 80's

[Warshadow]

During the oil crisis in the early 80's they worked on this. I'm fairly sure one company did add sails to a ship or two and did see a reduction in fuel consumption.

Also Popular Mechanics ran an article on this like 4 months ago. In fact it was on the cover of that issue.

Re:Welcome to the 80's

[Danga]

Also Popular Mechanics ran an article on this like 4 months ago. In fact it was on the cover of that issue.

I was trying to remember where I somewhat recently read about this technology and thank you for reminding me that it was in Popular Mechanics.

I can't find a link to the Popular Mechanics article (I think it was in the february 2006 issue) but you can read more about this technology here http://alt-e.blogspot.com/2005/02/hybrids-hybrid-b oats-hybrid-ships-and.html and the following link has some more information as well as some interesting pictures/diagrams http://www.primidi.com/2005/03/07.html .

It is pretty amazing how much more efficient the sails can make a ship, from the last link I mentioned:

"cargo vessels can increase their speed by a minimum of 10% -- in the example given speed is increased yet by 2.25 bends, equaling 15%. Alternatively by using the SkySails propulsion fuel savings of up to 50% can be implemented."

It showed that using 1200 litres of fuel per hour a normal ship would cruise at ~15.5 knots and a skysail enhanced ship would cruise at close to 18 knots, not too bad of a speed gain. If the skysail ship wanted to cruise at 15.5 knots instead then fuel consumption would drop from 1200 litres per hour to around 550. That is just awesome and I really hope this goes into wide use where it is feasable to use it.

What was old is new again

[iminplaya]

Sorry, this is the best I could find. I'm just not that good with this Google thing. I was looking for a picture, but FTL:
Rising fuel prices during the 1970s prompted the development of a new technology that used sails shaped like aircraft wings turned on end to take some of the burden off the engines and save fuel. Slightly curved to form a wing shape, these sails were attached to a mast that could pivot and locate the best angle for the sail to catch the wind. Once the computers set the mast at the best angle to the wind, the sail created the same "lifting" force that an airplane's wing generates, except that the force pushed the ship along the water. However, this system did not always prove to be efficient for extremely large vessels. I thought what I saw was that the mast itself was a rigid aerodynamic sail.

Re:How big?

[Cromac]

At this site http://www.bath.ac.uk/~ccsshb/12cyl/ the most powerful ship diesel running at its most efficient speed burns 1,660 gallons of heavy fuel oil per hour. Even using the cheap, nasty fuel these ships burn that's a big expense.

According to http://www.skysails.info/index.php?id=66&L=1

Increasing efficiency using ship diesel has almost reached its maximum potential and is also extremely expensive. According to the calculation of an expert on ship propulsions, shipping companies would have to invest up to 500,000 Euros in order to reduce a ship's fuel consumption by 1%. Fuel savings of 5% would be a fantastic performance for ship owners, according to Niels Stolberg, managing partner of Bremen-based shipping company Beluga Shipping GmbH.

To get an increase of 35% (the max claimed by SkySails) would mean a 3.5 million euro investment, that's a lot of crewman salaries even at union wages and less than the Skysails implementation would cost.

They have some interesting performance calculations on their website too about how much sail produces how much energy. http://www.skysails.info/index.php?id=89&L=1

Re:I wonder about the article photo

[MathFox]

It takes some time to get a supertanker turning... but once they turn it takes significant time to stop the rotation. Rotational inertia can work against you.
Having the pulling force closer to the center of the ship will decrease the needed rudder force for correction; using the rudder creates friction, so that's best avoided. Another advantage of having the ropes mid-deck makes it possible to lower the kite on deck, much more convenient than fishing it out of the waves after use.

Re:I wonder about the article photo

[nacnud75]

The parasail behaves very differently to a normal triangular sail or even a jenica. You move the parasail constantly through the air in a figure of eight to generate power. Also these ships are likely to follow the trade winds where the wind normally comes from the stern, therefore attaching the sail to the bow won't be a problem as most of the time the ship would be traveling on a broad reach or run.

Re:Tugboat attachment points

[alshithead]

Most newer freighters and tankers can pretty much dock themselves. The have bow and stern thrusters that make them very maneuverable at low speed. These days tugs are more of a backup system for docking ships. They'll tie on and sit at the ready but the pilot on the ship is doing the docking using the bow and stern thrusters.