The Town of Islip Bay Constables were on one of the Town of Islip T-band frequencies (470.3625 MHz) before they were shut down due to budget constraints at the end of 2012. They were brought back part time on a seasonal basis for the summers of 2013 and 2014.
The Town of Islip UHF T-band channels are now digital, maybe Turbo, not quite sure, but definitely digital (even though their license WEC745 is for narrow band analog).
Islip Town T-band frequencies are alive and well buzzing with digital noise that I can't understand, but I have also heard some of their marine units (as well as land units) this summer on the SCPD 800 system using TG 1168.
As with any marine related public safety operation, you may hear them on the typical marine VHF channels talking to other vessels and/or the USCG on channel 16, and 22A if they are involved in an incident, but the common VHF marine band channels are not used to dispatch them to any calls.