Except that car travels at 2.85 times the speed of the wind, when directly downwind, ie. when the boat and wind velocity vectors are on the same axis.
Of course, since the "sails" (the propeller blades) are moving on a different trajectory, their apparent wind is not directly downwind.
That would be merge sort, not quicksort.
Quicksort is (basically) :
- choose a pivot value
- quicksort the list of elements with a value lower than the pivot value (list 1)
- quicksort the list of elements with a value higher than the pivot value (list 2)
- add the pivot and list 2 to list 1
Numeric stability is probably not all that important when you're guessing.