You won't find ferry wake bothering you on a Hawksnest mooring by that tiny pocket beach.
It was always a fine day stop but has nothing special to offer beyond general good STJ snorkeling.
A day stop at the Mary Point mooring is a snorkel treat, or Whistling Cay moorings [pay attention to current] -- then an overnight in the Francis or Maho mooring field makes for a great 1st day.
Mermaids Chair is generally referring to the western end of STT -- the STJ Hawksnest pocket beach reference is a relatively new internet appellation.