Following a three-month overhaul, three weeks of refresher training, and almost two months of local operations, "Abnaki" departed Pearl Harbor on 29 March 1966 for the western Pacific. She stopped at Guam along the way, before arriving in Nagasaki, Japan, late in April. The fleet tug towed an Army power barge from Nagasaki to Naha, Okinawa, for 12 days of upkeep. She departed that port on 19 May and arrived in Da Nang, South Vietnam, on the 22d. Between 23 May and 20 June, "Abnaki" operated in the South China Sea in support of 7th Fleet ships assigned to Yankee Station and made an overnight stop at Da Nang on 20 and 21 June before getting underway for Hong Kong. The ship remained in Hong Kong from 25 June to 2 July and then headed for Subic Bay for an upkeep period which occupied her for the bulk of July. On 26 July, she put to sea for Yokosuka and – after a stop at Buckner Bay, Okinawa – arrived at that port on 5 August. The tug stood out of Yokosuka a week later, towing LSSL-102, and moored at the Army pier at Sattahip, Thailand, on the 29th. She remained in Thailand, making one liberty call at Bangkok, until 22 September. Getting underway that day, the tug shaped a course for Kaohsiung, Taiwan. After nine days of upkeep at Kaohsiung, she set sail for Guam on 8 October and picked up her final tow of the deployment there on 16 October before steaming on toward Vietnam. She anchored off Vung Tau on Navy Day 1966, transferred her charge, and then got underway on 28 October to return home via Sasebo and Yokosuka.