Authors: Ben Ruhe
Date Submitted: May 31, 2006
Article Type: Journal

Sky Sails, a German firm based in Hamburg, has begun oufitting cargo ships with massive kites designed to tug vessels and reduce their fuel consumption. The firm estimates these kites will reduce consumption by about a third. This is a huge saving, given that fuel accounts for about 60 percent of shipping costs.

The idea of reintroducing standard sailboat sails was tried earlier. Testing this at the end of the last century, Japanese and Danish companies found that the required mast posed insurmountable problems because of the cost of strengthening hull and deck against extra stress, drag, instability of the boat in high winds, and the enormous deck space required by pivoting sails—-valuable space which would otherwise be used to store containers.

If the sails are actually kites, however, the equation changes radically. Attached to a structurally solid bow, the flying kites solve many of the problems posed by spinnaker sails. Flying at 100 to 300 meters above the sea, where winds are less turbulent and on average 50 percent stronger than the winds that sailboat sails capture, it is projected they will recoup the cost of installation ranging up to $4 million, depending on the vessel’s size, within a half dozen years. This is a fraction of the cost of using standard carbon fiber sails.

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