On Wed, 22 Jul 2015 10:04:23 -0500, Califbill billnews wrote:

I remember a similar proposal to put the sails like on the the last
America's cup boats on a freighter to get some extra push. More practical
idea. Computer controlled, no dangerous cables to the sail.


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Wing sails. One problem is that they can't be reefed down in high
winds. The America's Cup boats use a crane to remove them every
night, and they have three or four different wing sizes depending on
the wind strength they are expecting on any given day.