It should be. From Central (Pier #8 East wing), it departs:
8a-11a @ :00, :20, :40
11a-5p @ :00, :30
5p-8p @ :00, :20, :40
From TSTE, it departs:
7:50a - 10:50a @ :50, :10, :30
11:15a - 4:45p @ :15, :45
5:10p - 7:50p @ :10, :30, :50
$4.5, Octopus accepted.
This is from a ferry fan site based in Hong Kong, and should be up-to-date:
www.barcaferry.com