The second Mackinac (AVP-13) was laid down 29 May 190 at Puget Sound Navy Yard, Bremerton, Wash.; launched 15 November 1941; sponsored by Mrs. Ralph Wood, wife of the commanding officer, Naval Air Station, Seattle, Wash.; and commissioned 24 January 1942, Comdr. Norman R. Hitchcock in command.

After 3 months of trial runs, Mackinac, escorting a large convoy, sailed for Pearl Harbor 11 May, arriving 19 May. On 22 May famous explorer Rear Adm. Richard E. Byrd (retired) and his staff came on board for an inspection cruise of U.S. bases in the South Pacific, debarking at Auckland, New Zealand, 23 June. The seaplane tender then headed to Noumea, New Caledonia, 18 July.

With preparations underway for the Guadalcanal-Talat landing 7 to 9 August, Mackinac was assigned the task of setting up a seaplane base at Malaita, the most advanced post of the campaign, while her PBYs searched the sealane between Truk and Guadalcanal. One of the first ships to anchor in the Solomon Islands, Mackinac retired to Espiritu Santo 12 August.

Despite constant evacuation alerts and numerous searchplane losses, Mackinac next setup base at Graciosa Harbor, Santo Cruz, 20 August. Early morning, 12 September, two submarines surfaced at the harbor entrace to shell Mackinac and Ballard (AVD-10), together with their planes. The tenders retaliated; but no damage occurred for either side.

Following her return to Espiritu Santo, New Hebrides on 25 October Mackinac assisted with her boats In rescuing survivors of President Coolidge after the Army On 12 November "Mighty Mac" established an advance seaplane base at Vanikoro Island, Santa Cruz, and begn tending an average of six planes a day. Several high-ranking officers visited her during this duty, including Vice Adm. W. F. Halsey.

Mackinac got underway from Espiritu Santo with a convoy for the west coast 9 July 1943, arriving San Francisco 25 July for overhaul. The tender returned to Pearl Harbor 28 September. After a month of transport duty between Midway and Maui Hawaii, Mackinac left Pearl Harbor with Curtiss 20 November for the Ellice Islands.

When a PBY was forced down near Nui, Gilbert Island, Mackinac, after locating it early 24 November, rescued the crew and safely towed the plane to Nuku Fetau despite adverse weather. On 1 December she arrived at recently secured Tarawa to tend planes there through January 1944, despite some 22 air raids.

Mackinac then steamed for Makin with VPB-72 (Navy medium patrol bomber squadron 72) to participate in the Marshall campaign with around-the-clock seaplane tending. With the strategic atolls of Majuro and Kwajalein secured by the early part of February, the ship was ordered on to Kwajalein, anchoring 9 March. While her squadron was conducting rescue operations at Majuro, Makin, Eniwetok, and Kwajalein, she was laying out the seaplane area and assisting the construction of a naval airbase on Ebeye Kwajalein.

On 23 June Mackinac departed for Eniwetok en route to Saipan. As the conquest of Saipan was still in the assault stage, Mackinac was under almost constant fire while stationed there.

Relieved 19 August, Mackinac joined Chandeleur (AV-10), Pocomoke (AV-9), Yakutat (AVP-32), and Onslow (AVP-48) in sailing for Kossol Passage, Peleliu, Palau Islands, arriving 1 day after D-Day, 15 September. For the next 3 months Mackinac marked navigational obstructions off Kossol before leaving for Ulithi 25 December. On 21 January 1945 Mackinac got underway with Chandeleur for San Diego via Pearl Harbor, arriving 7 February. The ship returned to Saipan in April.

On 11 May Mackinac joined a seaplane group based at Kemma Rhetto, Ryukyu Islands, during the Okinawa operations, and continued a variety of duties, including air-sea rescue and bombardment of Japanese held Rose Island. After the group moved operations to Okinawa 14 July "Mighty Mac" tended motor torpedo boats through early August. After the Japanese capitulation 15 August, she was assigned to Join TG 30.5, arriving Sagami Bay, Tokyo, Japan, 28 August.

Following occupation duty, Mackinac left for the west coast 10 January 1946, arriving San Pedro, Calif., 29 January. After repairs, she sailed for the Atlantic via the Panama Canal, arriving Orange, Tex., 26 March. Mackinac decommissioned and entered the Atlantic Reserve Fleet at Orange, Tex., January 1. She was transferred to the U.S. Coast Guard in April 199 and served as Mackinac (WHEC-371) until returned to the Navy for use as a target to destruction early in 1968.

Mackinac received six battle stars for World War II I service.