The Return of Commercial Sail ‚Äď UT Wind Challenger & Retracting Rigid Wing Sails
Early airplane wings were built of canvas¬†stretched¬†over a wooden frame, held together with wire rigging. ¬†Modern airplane wings are built of aluminum and other metals. ¬†The comparison to sails, masts and rigging on ships may not apply directly. ¬†Nevertheless, the last America’s Cup winner, the US-17, formerly known as the BMW Oracle Racing 90,¬† screamed to victory in 2010, sailing on a 223 feet rigid wing sail, more than 80 percent larger than the wing of a Boeing 747 airplane. Now a Japanese group, including¬†engineers¬†from the¬†University¬†of Tokyo, are developing the design of a¬†merchant¬†ship with retracting rigid wing sails, the UT Wind Challenger.
We recently posted about the efforts of B9 Shipping and¬†Fairtransport¬†to¬†develop commercial¬†sailing ships using an automated “Dynaship/Dyna-Rig,” similar to that used on the¬†sailing¬†yacht¬†Maltese¬†Falcon. ¬†The Dyna-Rig approximates the¬†aerodynamic¬†efficiency¬†of a wing sail while still using cloth sails.
The UT Wind Challenger uses¬†aluminum¬†and reinforced plastic hollow wing sails. ¬†The UT Wind Challenger team has addressed¬†a major¬†problem¬†with wing sails – that¬†they¬†are difficult to manage in port, by using what they refer to as “vertical reefing,” the wing sails retract into themselves. ¬†It appears that the UT wing sail design could be applied to considerably larger ships than is currently being¬†planned for¬†those¬†ships using the Dyna-Rig. ¬† The¬†developers¬†estimate a 30% savings in fuel consumption using the wings sails, which sounds like a rather conservative estimate given the sail area involved. There are plans to build a reduced scale prototype to test the concept by around 2016.