i highlighted copied and pasted into google search this url
http://www.yamaha-motor.jp/marine/index.html
and then clicked translate in results to get a "kind" of english
it seems this is their chosen way to drift fish and keep the bow into the wind
i put out a drogue to keep the bow to the weather on a drift, but this has me intrigued
has anyone ever seen or used a twin rear sail arrangement like this
adjustment seems to be on how far apart you spread the 2 booms and sails
the sails create 'adjustable' drag, there is no drive with them
they have gone to a lot of trouble to create this set up, must be something in it
it is used on large craft too