If you belong to a yacht club of any sort, the Ida Lewis YC will rent you a mooring on a reciprocity basis (our dinky little Maine YC has no formal reciprocity policy, but it didn't matter when we were there over July 4th this summer) at a very reasonable rate that includes launch service and showers. Located very near Ft. Adams and close to the NYYC facility so you can watch the 1%s and their yachts. Nice facility and friendly.