It may be useful for you but in the grand scheme all the new ferries cover only a trivial percentage of the total number of daily trips.
They don't compare remotely favorably to the subway along any axis except start-up cost (it's cheaper to buy a boat and build some piers than to build a subway tunnel).
Which is, well, hugely significant when you think about it.
But I guess those discussions will need to happen elsewhere.
Some people tried to make the math work for the L shutdown and even if you had a line of ferries just following each other as close as safely possible it wouldn’t be nearly enough. Subways are incredibly efficient at moving large numbers of people.