Only by sections that I know of as for fireworks displays, Op-Sails etc. These times of course there was prep time. They shut down the Hudson PDQ when that plane went in.
The fact is though, once you’re on the water, where ya gonna go? Your choices of path and destination are very limited.
I owned boats in NYC in the 70s and 80s. Worked on open boats in the late 80s, late 90s and 00. I got pretty familiar with the waterways in and around NYC.
What I’m saying is that an escape from Manhattan by water, although possible is not really probable.
Just looking at the map, it seems as if there are several directions to go.
You have been there. What are the problems with going either up the Hudson, down the Hudson, or off the other side of Manhattan?
If someone is fleeing the city, once they get to the Atlantic, the whole world opens up.