Marine Link has an excellent overview of the increasingly useful Nationwide Automated Identification System (NAIS) and the R&D Center’s role in its development.
As for the Coast Guard’s own use of the system, we have this press release from FLIR.
WILSONVILLE, Ore., October 16, 2018 – FLIR Systems, Inc. (NASDAQ: FLIR) announced today that it has been awarded a contract from the United States (U.S.) Department of Homeland Security (DHS) in support of the U.S. Coast Guard’s (USCG) Second Generation Automatic Identification System (AIS-2) program. The indefinite delivery indefinite quantity (IDIQ) contract has a ceiling value of $9.9 million to provide second generation Automatic Identification System (AIS) transponders, associated peripherals, and spare parts for nearly 1,774 boats and 282 cutters in the USCG’s active fleet.
The government anticipates the purchase of vessel class-specific kits and spare parts to equip all USCG vessels with AIS-2 over the next five years.
“We are pleased to provide AIS hardware and software technology to support the US Coast Guard’s mission,” said Jim Cannon, President and CEO at FLIR. “Our technology will provide enhanced levels of secure communication and coordination between Coast Guard boats, cutters, and shore stations (emphasis applied–Chuck). This award further extends our technology partnership with the Coast Guard, providing next-generation communication capabilities to complement their Raymarine SINS-2 navigation systems.”
I was a little surprised to see reference to secure communications in conjunction with AIS because I don’t associate those two things, but it is apparent we are finding new uses for the system, including as a blue force locator.
It looks like we will be putting these systems on even our smallest boats. Ran across a study that may provide an indication (Note this is apparently a Russian URL) of where we are going with this.
Chuck Hill's CG Blog 
Acquisitions Directorate (CG-9) release today. https://www.dcms.uscg.mil/Our-Organization/Assistant-Commandant-for-Acquisitions-CG-9/Newsroom/Latest-Acquisition-News/Article/1664712/coast-guard-nais-transitions-to-sustainment/
The Nationwide Automatic Identification System (NAIS) transitioned to sustainment Aug. 26 2018, completing a 14-year process that enhances the Coast Guard’s maritime domain awareness (MDA) of vessels operating in or approaching the nation’s waterways, ports, and infrastructure.
NAIS reached full operational capability on May 24, 2018, at a total acquisition cost of $110 million. Despite the complexity of this major acquisition, the NAIS program diligently deployed equipment on time and under budget to 134 sites across 37 sectors.
The NAIS program was chartered in December 2004 to meet requirements under the Maritime Transportation Security Act of 2002 to collect, integrate and analyze information regarding vessels operating in or bound for U.S. waters. The acquisition consisted of three increments. Increment one established the shore-based capability to receive AIS messages at 58 critical ports and 11 waterways using existing government infrastructure in coordination with the roll-out of Rescue 21. Increment two implemented transceiver capability to transmit and receive data up to 24 nautical miles and receive data up to 50 nautical miles. Increment three combined permanent transceivers with satellite coverage to observe maritime traffic up to 2,000 nautical miles from the coast.
NAIS is a critical capability, enabling the Coast Guard to develop and maintain MDA in U.S. waterways through the use of land, sea, and space based AIS radio frequency infrastructure that has the capacity to receive and transmit information to and from AIS equipped vessels in U.S. coastal waters and ports.
On average, NAIS receives approximately 120 million messages per day and provides data feeds to over 80 Coast Guard and other government agency systems. Additionally, NAIS enables Coast Guard to track vessel names, positions, courses and speeds in real time; track federal, state and local government responder vessels using sensitive but unclassified tactical information exchange and display system messages and encrypted Blue Force Tracking data; issue commands to vessels; and provide historical information for use to augment incident investigations.
Additional government agencies utilizing NAIS data include Immigration and Customs Enforcement, U.S. Army Corps of Engineers, Customs and Border Protection, National Oceanic and Atmospheric Administration, Department of Defense, Internal Revenue Service, and the Department of Transportation. NAIS positions decision makers in each agency to respond to safety and security risks and strengthen national security through the detection, identification and classification of potential threats from offshore.
Moving forward, the Office of C5I Program Management (CG-68) will act as the sustainment manager and will be responsible for overall system operations and maintenance of NAIS. The NAIS support agent – the Command, Control, and Communications Engineering Center (C3CEN) – will be the owner of the NAIS Sustainment Product Line. Hardware and software will be supported and maintained by the Operations Systems Center (OSC), which is also where the NAIS enterprise environments are hosted.
Additionally, two contracts are in place to provide corrective maintenance as well as engineering support services for information assurance, system administration, groom processes and detailed troubleshooting requirements.
For More Information: Nationwide Automatic Identification System program page: https://www.dcms.uscg.mil/Our-Organization/Assistant-Commandant-for-Acquisitions-CG-9/Programs/C4ISR-Programs/NAIS/