Those are no doubt the Special Arrangements I mentioned:

"Under the special arrangements, the master will not be required to anchor the yachts at immigration anchorage for immigration examination, provided that he or his representative presents, within 24 hours before the intended departure or after the arrival of the yacht in Hong Kong waters, the documents mentioned above to the Harbour Control Office at 2nd floor, Central Government Pier, 32 Man Fai Street,Central for examination."

That's from a notice for yachts, but similar arrangements exist for commercial ships.