Powered boats can do this too.  They can motor up against the current to match the speed of the current.  That way they can be stationary with the land and yet move sideways!  It can help manoeuvre in tight spaces (Though very few skippers seem to know how to do it, despite its simplicity and usefulness).<br><br>Funnily enough, it's called ferry gliding!  And now I know why :)