She was originally USS Shackle (ARS-9), a Diver-class rescue and salvage ship commissioned by the United States Navy for service in World War II.

She was responsible for coming to the aid of stricken vessels and received three battle stars during World War II, before a long career with the Coast Guard.

Acushnet patrolled the waters of the North Pacific and was one of the last World War II era ships on active duty in the US fleet upon her retirement in 2011.

Shackle's first station was at Pearl Harbor, Hawaii, where she served as a salvage ship in the West Pacific throughout the remainder of World War II.

Shackle's first year was spent completing extensive salvage assignments clearing wreckage in the channels at Pearl Harbor and Midway Island.

Between D-Day (April 1, 1945) and September 20, 1945, the ship completed 55 salvage and rescue operations on larger naval craft damaged by kamikaze attacks.

Shackle cleared the vital docking area of the wreckage of a sunken Japanese cable laying ship at Yokosuka Naval Base, Tokyo Bay, Japan.

On August 23, 1946 USS Shackle was commissioned into the United States Coast Guard as USCGC Acushnet (WAT-167), a search and rescue vessel and was homeported in Portland, Maine.

First homeported in Portland, Maine, as a Coast Guard tug, and renamed USCGC Acushnet (WAT-167), she earned a sound reputation as a dependable friend to fishermen and boaters in distress.

A few of Acushnet's more noteworthy cases during that time frame include the following: in 1960, she salvaged the 300-ton USCGC General Greene which had been driven one hundred yards ashore in high winds.

One of her more dramatic cases in Portland included the rescue of the entire crew of ten people from the disabled seagoing dredge Cartagena, which was adrift in 30-foot (9.1 m) seas and 75-knot (139 km/h; 86 mph) winds, 200 nautical miles (370 km; 230 mi) off of Cape Cod on Christmas Day, 1961.

During fiscal year 1970, she underwent conversion during which alterations were made to her hull and scientific equipment, and research and storage spaces were added at a shipyard in San Diego, California.

As part of the National Data Buoy Project of NOAA Acushnet spent three years attached to the Office of Naval Research and the Scripps Oceanographic Institute in San Diego, California.

In the fall of 1973 the cutter played a major role in the Key Largo fire south of New Orleans opposite the town of Phoenix.

Acushnet and the cutter Dependable were presented the Coast Guard Unit Commendation for extinguishing a fire on the tanker Key Trader after she collided with another vessel, the Norwegian ore ship Baune, and burst into flames in the river.

Additionally in 1978, Acushnet was designated a Medium Endurance Cutter (WMEC 167) and was formally assigned law enforcement and search-and-rescue missions.

Between 1987 and 1989 Acushnet had yet two more seizures of marijuana and hashish oil valued at over 1.5 million: MV Blind Melon[6] and sloop Stormy Weather.

She also responded to a mayday call made by the fishing vessel Tonquin in the Gulf of Alaska, rescuing one man out of a five-man crew from stormy and frigid waters during a five-day search.

During the operation, she was featured on the 5th season of the reality TV show Deadliest Catch, although footage shown was of USCGC Alex Haley.