Turk, it is the currents and not the tides you will have to worry about. Tide is the vertical movement of the
water and just affects
depth (which you'll have plenty of) and the associated "sideways" movement of the
water is
current. Which is a problem in the East River.
I hope you are not planning to go UP the East River to join the
Hudson, you must go down to the
Battery and around Manhattan. The bridge clearances/openings on the north part of the East River are essentially impossible for sailboats.
A copy of Eldridge, the yellow/orange colored book available in any local
chandlery, will give you tide and
current information for the whole trip, along with a lot of other good information.