The moorings I deal with mostly these days are in Ayala Cove at Angel Island. You have to pick up two moorings here, fore and aft, because of the swirling currents. The floats are big heavy things with a horizontal ring rigidly attached to the top.
I had a particularly grim experience last summer. There was some event going on the island and there were a couple of ferry boats zooming back and forth bringing people over from Tiburon. One ferry came in particularly fast just as my crew was trying to slip a rope through the buoy with is finger tips. His wake lifted the bow way up and slammed us down right on the buoy putting a nice ding in my bow. Grrrrr.