when in doubt, follow the slowest boat
So, I made my first 40 Mile trip to Fire Island, and although I have a Garmin 740 chartplotter, the channels are not that obvious when you're bouncing around on the high seas....
So, I watched the ferries, and then tracked behind a old house boat thing going 17 mph, and got the main channel recorded on my Garmin.
The Bay here can be very shallow, and I already replaced my engine couper last year.
Unless, you grew up on a waterway, first time noting the channels is challenging.
Something to be said for rafting up, at then end of your canel.... lot less headaches....