If the PTB wanted to, they could very easily. West 79 st. Marina, East 23 st. marina and Battery Park marina are it.
You are more expert on NYC than I am, for certain.
To take advantage of your experise.
In your opinion, would they want to shut down the waterways? Have they done so in the past?
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.