Unscheduled Post: Faster than the speed of wind
Terence Tao has a beautiful analysis of sailing, in particular:
One of the more unintuitive facts about sailing is that it is possible to harness the power of the wind to sail in a direction against that of the wind or to sail with a speed faster than the wind itself, even when the water itself is calm.
Using his model he shows that:
…one could in principle reach arbitrarily large speeds and directions…I do not know however if one could actually implement such a strategy with a physical sailing vessel.