I've seen this before but one point and one question. First those bags are holding a whole lot of water weight. Gives you an idea of the power a set of sails generate when healed in that position. Second, it may be obvious but I'm missing it. How did he upright that boat on the other side?
Look closely at the end of the video.........he has lines attached to the "balls" (I think that they are divers lift bags, inverted to hold water) and he hauls them in towards the boat.
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Do not go where the path may lead.........
go instead where there is no path........
and leave a trail.
Ralph Waldo Emerson
Clever indeed! That's not a new video, but I still enjoy seeing it again. And kids today say "why do I have to grasp Newtonian physics? Everything's quantum!"