After two berth shifting operations early in May 1945, the tug got underway on 23 May 1945 with a barracks ship in tow, bound for the western Pacific.

These salvage operations included retracting two Landing Craft Infantry (LCI) from the beach and an Auxiliary Mine Sweeper (YMS) from a reef.

In the spring of 1946, she supported preparations for Operation Crossroads, a two-detonation atmospheric nuclear test held in summer, 1946 at Bikini Atoll in the Marshall Islands.

Aside from an overhaul at Puget Sound in the summer of 1947, the tug operated for the next six years out of the Alaskan ports of Kodiak, Cold Bay, Adak, Anchorage, Attu and Dutch Harbor.

Upon arrival in Seattle on 2 July 1953, she was transferred to the 13th Naval District and ordered to prepare for assignment to the Military Sea Transportation Service (MSTS).

The tug was transferred to the Maritime Administration, for lay-up in its National Defense Reserve Fleet (NDRF) at Olympia, Washington, on 25 August 1958.

A unit history written by an anonymous crewman sometime in the mid-1970s noted: "Designed and built from the keel up along the lines of a classic European oceangoing tug, the MODOC will literally tow anything afloat.

While Ivy was waiting out a storm at anchor in Willapa Bay, Washington; Ivy was called to assist the Japanese M/V Suwaharu Maru carrying a cargo of logs and the Liberian M/V Mandoil II carrying a cargo of naptha which had collided 340 miles from the Columbia River Bar off the Oregon coast.

In heavy seas, darkness and a snow storm Ivy rescued 68 crewmen from the Japanese vessel, which had jettisoned logs in an effort to stay afloat.

"On 3 June 1972 an off-duty Modoc crewman, SA James Carignan, of Olympia, Washington, drowned while attempting to save a 12-year-old girl who had been swept away from a beach by the surf.

It was first observed fishing off California in 1975 off Half Moon Bay on January–14 by a Coast Guard Air Station aircraft patrol from San Francisco.

During April and May of this year Coast Guard patrols observed the KALMAR fishing off Point Reyes, Half Moon Bay and Santa Cruz.

"In August 1975 Modoc safely towed the disabled East German stern-trawling factory-ship Rudolph Leonhard to Coos Bay.

In November of that year, during a severe gale, she attempted to locate the hulk of the Korean fishing vessel Kwang Myong No.–96 that had been abandoned by her crew after a fire.

While returning to her home port on 18 December 1977, Modoc narrowly avoided a collision with the loaded 810-foot tanker Arco Sag–River at the mouth of the Strait of Juan de Fuca.

Modoc put to sea on New Year's Eve 1977 to assist in the seizure of the Panamanian-registered MV Cigale off the mouth of New River, south of Bandon, Oregon.