Description : Let's experiment with
different boat/river velocities. You have a boat that has a fixed
speed relative to the water, and you want to get across the river. The
simulation initially shows the boat aiming straight across the river
(and ending up downstream). There is a dock (in blue) directly across
the river .. it would be nice to get there. But there is an IceCream
place just upriver from the dock, it would be BETTER to get there!