There’s an interesting way to reduce the operating cost of ships using the power of the wind. A Sky Sail has been invented by SkySails, a german company, which helps “tow” a ship through the water, reducing fuel consumption. The Sky Sail resembles a large parachute. It is different from a regular sail as used on sailboats, in that it is tethered by a very long cable and flown like a kite high above the ship. This utilizes the stronger winds found at higher altitudes.
The sky sail can be flown as high as 100 – 300 meters above the ship. Its area ranges from 150 to 600 m2. It can reach a pulling force of 8 to 32 tons, which can reduce fuel consumption by 10 to 35%.
Its makers claim that the sky sail can easily generate five times more propulsion power per square meter of sail area than conventional sail propulsion. And plans are in the works to construct sails which can pull with a force of up to 130 tons.
The towing kite is made of high-strength and waterproof textiles. It is easy to store and occupies little space when folded.
The wind doesn’t need to blow directly behind the sail to achieve a high towing force. It can blow at right angles to the ship, and still provide a high level of towing force by adjusting the position of the sail relative to the ship.
The most efficient use of the Sky Sail will likely be in ocean travel, by utilizing the Trade Winds and the Westerlies. These wind systems are very consistent and reliable. They were used by early explorers to travel from Europe to North America and back again. The figures below show illustrations of the global wind system.
As an example, if one wishes to travel from Europe to North America using the Sky Sail, they can navigate within the (east-to-west) Trade Wind stream. And to return to Europe they would navigate along the northern stream blowing along the east coast of North America, and then take the westerly (west-to-east) stream back home.
The ships engines would be primarily used for docking and undocking, and to navigate in those regions lying outside the Trade Winds and Westerlies. Once the ship reaches these wind systems the Sky Sail can be deployed and the engine power throttled back.
This is a great idea! It’s stupid not to take advantage of the high winds up in the atmosphere – especially when out in the middle of the Pacific. Great way to save on fuel and maximize profits without affecting shipping time.
Maybe this will lead the way to future sailboats – taking advantage of the high-speed jet-stream winds for trade.