Pull your chart for Fishers Island/Stonington Harbor, Conn. East of Stonington Harbor entrance/breakwater there is a channel heading east towards Watch Hill, RI. This channel is not very wide, nor exceptionally deep and quite curvy as one proceeds eastward towards Watch Hill. It is not for the inattentive but well marked, as I recall. Once into the area of the town and marina, there is limited space. A close review of applicable charts is most prudent. Both for depth and direction. Pretty town, but quite a limited harbor area. Stonington is the much larger harbor and marinas if you are looking for service.
There's a Watch Hill Marina on Fire Island, NY, and there's a Westerly Marina, near Watch Hill in Rhode Island. I don't believe there would be anything in Northern CT, of that name. What are you looking for? Service? dock space? I'm in RI - let me know if you're heading this way and I'll help if I can.