Use NOAA Chart 12372.
From the Connecticut River channel west of Great Island, pick up flashing red buoy 14, and then head west toward green can 15, which marks the beginning of the approach to North Cove. Once you have picked up green can 15, follow in green can 1, red nun 2, and green can 3. The chart lists the depth of the approach channel at five feet, with four- to five-foot depths inside the cove itself.
There is a yacht club on the far side of the cove that May offer reciprocal privileges for qualifying members of other yacht clubs, but most people tuck into NOrth Cove to grab a spot and drop the anchor for the evening.
North Cove is located just upstream from Saybrook Point on the Connecticut River in the town of Old Saybrook. Although there is only one private facility on North Cove (no transient facilities), there is limited anchorage room, and you May be able to make use of a vacant mooring if the resident is gone (at your own risk).