Warship Wednesday, Feb. 22, 2023: A Dozen Stars and a Wigwam

Here at LSOZI, we take off every Wednesday for a look at the old steam/diesel navies of the 1833-1954 time period and will profile a different ship each week. These ships have a life, a tale all their own, which sometimes takes them to the strangest places.- Christopher Eger

Warship Wednesday, Feb. 22, 2023: A Dozen Stars and a Wigwam

U.S. Navy Photo by JOC(AC) Warren Grass. National Archives Catalog #: 80-G-K K-98130

Above we see the unpresuming Navajo/Cherokee/Apache-class fleet tug USS Tawasa (AT-92) departing Subic Bay bound for Haiphong in February 1973 to take part in Operation End Sweep. Don’t let her workaday appearance fool you, launched eight decades ago today– 22 February 1943– she saw more hairy situations than many battleships across her 32-year career and helped boil the sea.

A new type of tug, for a new type of war

With the immense U.S. Naval build-up planned just before WWII broke out, the Navy knew they needed some legitimate ocean-going rescue tugs to be able to accompany the fleet into rough waters and overseas warzones. This led to the radically different Navajo/Cherokee class of 205-foot diesel-electric (a first for the Navy) fleet tugs.

These hardy 1,250-ton ships could pull a broken-down fleet carrier if needed (Tawasa would prove that in 1965) and had long enough sea legs (10,000 miles) due to their economical engines to be able to roam the world. Armed with a 3″/50 caliber popgun as a hood ornament, a matching pair of twin 40mm Bofors, and some 20mm Oerlikons, they could down an enemy aircraft or poke holes in a gunboat if needed.

In all, the Navy commissioned 28 of these tough cookies from 1938 onward, making a splash in Popular Mechanics at the time due to their impressive diesel-electric power plant consisting of a quartet of GM 12-278A diesels driving four GE generators and a trio of GM 3-268A auxiliary services engines, generating 3,600shp.

Their war was hard and dangerous with 3 of the ships (Nauset, Navajo, and Seminole) meeting their end in combat, and the 25 that made it through the crucible going on to serve in other conflicts, and under other flags.

The Cherokee/Navajo class would prove successful enough that 22 follow-on tugs– with the same hull form and engineering plant but with a re-trunked exhaust that shrunk the funnel diameter– of the Abnaki class would be constructed during the war, and two (Wateree, lost in a 1945 typhoon; and Sarsi, sunk by a mine off Korea in 1952) lost in Navy service. 

Meet Tawasa

The hero of our story, USS Tawasa (AT-92) was laid down on 22 June 1942 at Portland, Oregon, by the Commercial Iron Works, a small firm that would crank out no less than 188 hulls for Uncle Sam during the conflict ranging from landing craft to escort carriers. Tawasa’s launch date, some 80 years in the rearview, saw her sponsored by Mrs. Thomas F. Sullivan, the tragic gold star mom of the five lost Sullivan brothers.

The first U.S. Navy vessel named for a Florida branch of mound-building Muskhogean Indians subsequently named the Apalachicola tribe, she commissioned on 17 July 1943, just under 13 months after her first steel was cut.


Following her shakedown cruise off California, Tawasa was assigned to Service Force, Pacific Fleet, and left Pearl Harbor in early November, bound to spend Thanksgiving 1943 in the Gilbert Islands, which were being taken by Marines.

USS Tawasa (ATF-92) underway, circa 1943-1945, location unknown. David Buell for his father CWO4 Benton E. Buell USN, Ret. USS Tawasa Chief Engineer, 1962-63. Via Navsource http://www.navsource.org/archives/09/39/39092.htm

Christmas saw her in Tarawa and the New Year of 1944 with TF 52 pushing through the Marshall Islands, where she lent a hand in the landings at Kwajalein, Majuro, and Eniwetok, at times pinch-hitting as a destroyer acting as a screening vessel with her overheating and cranky WEA-2 sound equipment in the water. Her ASW armament if she had a contact? Just eight “ashcan” style depth charges on two short gravity racks over her stern.

As noted by DANFS:

Off Kwajalein Atoll on the 31st [of January], Tawasa took soundings enabling Mississippi (BB-41) to approach the shore for close bombardment. The tug then performed salvage, towing, and screening duty until 18 February when she moved to Eniwetok to assist in the assault that was to strike that atoll the next morning. She supported operations until the atoll was secured and remained in the area for almost two months, providing services to American ships using this new base.

Tawasa’s War Diary for 30/31 January 1944:

Continuing with TF52, she would soon be assisting combat-loaded LSTs landing Marines and gear on Saipan in June.

With the Marianas wrapping up, by late July Tawasa would be reassigned from TF52 back to ServRon, South Pacific, and placed on a series of unsung missions. She became particularly adept at pulling LCIs off the beach. Her embarked divers came in handy when it came to recovering lost anchors and chains, along with conducting submerged inspections of recently captured ports and leaky hulls, while her DC teams would often fan out to weld 1/4-inch steel sheeting over holes in the side of battle damaged landing craft. Her 20-ton derrick boom allowed her to salvage all manner of objects from the seafloor. Meanwhile, her sonarmen and radar operators would keep their eyes and ears peeled for interloping enemy aircraft and vessels of all types.

The Japanese surrender found our tug in Guadalcanal, where she had just transported military passengers from the Russell Islands. Post VJ-Day, she remained forward deployed except for a trip stateside to California and would operate in Chinese and Japanese waters well into 1947.

In the end, Tawasa would earn three battle stars for her WWII service.


While a wide variety of brand new ships wound up in mothballs in the days after WWII– some being towed to red lead row right from the builders’ yards– these fleet tugs remained on active service. No rest for the working man.

The Cherokee class fleet tugs listed in the 1946 Jane’s, Tawasa included. Note that the list includes the Abnaki-class half-sisters as well.

Alternating between Alaska and Guam in the late 1940s and early 1950s, Tawasa was deployed to the 7th Fleet to serve in the Korea conflict, assigned alternatively to the ports of Cho Do, Sokcho, and Chinghai while under the control of TF 92 from July 1952 through January 1953. In this, she added two further battle stars to her salad bar.

Returning stateside, she spent six months in overhaul at the San Francisco Naval Shipyard. When she emerged in November 1953, a terrific series of images were captured of her for the U.S. Navy Bureau of Ships files, detailing her radar (SO-4), radio, and overall fit. If you are a modeler looking for shots of a 1950s Cherokee class tug, the National Archives has you covered with this series:

Note that she still carries her WWII twin Bofors mounts. 19-NN-ATF 92 Tawasa-145199

19-NN-ATF 92 Tawasa-145203

19-NN-ATF 92 Tawasa-145715

19-NN-ATF 92 Tawasa-145197

19-NN-ATF 92 Tawasa-145716

19-NN-ATF 92 Tawasa-145717

19-NN-ATF 92 Tawasa-145201

19-NN-ATF 92 Tawasa-145714

Note the two bridge wing 20mm single Oerlikons. These would be replaced by M2 .50 cals by Vietnam while the Bofors would be deleted about the same time. 19-NN-ATF 92 Tawasa-145202

19-NN-ATF 92 Tawasa-145200

19-NN-ATF 92 Tawasa-145198

19-NN-ATF 92 Tawasa-145713


Fielded in 1952 without full-scale war shot tests, the 500-pound Mark 90 “Betty” nuclear depth charge was seen as an ace-in-the-hole against rapidly growing fleets of schnorkel-equipped Soviet Whiskey-class submarines, of which Moscow ordered a staggering 215 in four different versions (Projects 613, 640, 644, and 665) between 1949 and 1958.

Carrying a W7 Thor tactical fission bomb with a theoretical yield of up to 30 kilotons– twice the force of the Hiroshima bomb– it was thought that a single Betty dropped via a patrol plane would be enough to clear out a whole nest of Whiskeys.

But the Navy wanted to be sure the theory held.

Enter Operation Wigwam, a full-scale test of a live device.

Conducted in May 1955 some 500 miles southwest of San Diego in water 16,000 feet deep, Tawasa tugged a Betty as part of a six-mile long towline that included a trio of identical white-painted 4/5-scale submarine hulls (704 tons, 140 foot long with a 20-foot beam complete with correct bulkhead spacings to spec and 1-inch HST steel hull plating) dubbed “Squaws” which were filled with instruments. 

The three Squaw submarine mock-ups generally mimicked the same hull construction techniques as seen on the Navy’s SS-563 (post-war Tang) class diesel GUPPY boats, which were at least as strong if not stronger than Soviet Whiskey boats. The targets were fitted with extensive seismography instruments at 52 locations spread throughout their compartments.

With the Squaws submerged at a depth of 250-290 feet at three different distances from the device, the Betty was rigged some 2,000 feet under the keel of its support barge and the Wigwam task force beat feet to observe from five miles away.

The resulting “hot” bubble from the submerged blast grew to over 4,600 feet across when it broke the surface and rose some 1,900 feet above the water at its height.

Squaw 12, the closest to the device, simply disappeared.

Here is the view from five miles out. Hydrophones at Point Sur, Hawaii heard the “thump” of Wigwam from 2,500 miles away. NARA 374-ANT-30-30-DPY-11-20

The gist of the 56-page after-action report on the squaws:

The external pressures applied to the three SQUAW targets in Operation Wigwam were measured with pressure gages, and the deformations of the hull were measured with strain and displacement gages. The results indicate that SQUAW-12 was at a horizontal range of 5150 ft and a depth of 290 ft the peak shock pressure at the hull was about 850 psi and the target was destroyed, probably within 10 msec. SQUAW-13 was at a horizontal range of 7200 ft and a depth of 260 ft the peak dynamic pressure at the hull was about 615 psi, and the hull was probably near collapse but did not rupture. The estimation is that the lethal horizontal range of the SQUAW target under the Wigwam test conditions is about 7000 ft for a depth of 250 ft and about 4500 ft for a depth of 70 ft.

Even though at least 362 personnel of the task force’s 6,732 men embarked– clad just in working gear with no flash or NBC protection– would have mildly dirty dosimeters after the event, and contaminated water was found at several depths during the weeks following the test, it was judged that Betty was safe-ish enough to be used under certain conditions, and was more than capable of sinking an enemy sub (or three) within a two-mile radius of its impact if used correctly.

This 11-minute film covers the test in great detail, including Tawasa and her six-mile squaw-laden towline.

Betty would remain in service until 1960 when it was replaced by the multipurpose B57 nuclear bomb during the mid-1960s. In its depth charge variant, the hydrostatic fuzed B57 had a selectable yield up to 10 kt– only about one-third of the Wigwam device– and could be dropped by P-3s, S-3s, and SH-3s as well as the short-lived Drone Anti-Submarine Helicopter (DASH). It was thought that in most scenarios, the B57 depth charge would only be dialed in at 5 kt. It would finally be withdrawn in 1993.

Anyway, back to our ship.


Dusting off and cleaning up post-Wigwam, Tawasa would continue to serve with the 7th Fleet on WestPac deployments, including four to Vietnam (May-Oct 1968, April-Sept 1969, May-Sept 1970, and Feb-June 1972). For this, she would earn seven Vietnam-era campaign stars.

Her most notable moments during this era included the largest operational tow made by a solo tug of the Pacific Fleet: 33,946 tons, when she pulled the decommissioned USS Bunker Hill (AVT-9) from San Francisco to San Diego, and coming to the rescue of the shattered destroyer USS Frank E. Evans (DD-754) which had been sheered in two by the Australian aircraft carrier Melbourne during Southeast Asian Treaty Organization exercises in the South China Sea.

Tawasa took the remaining stern section in tow and returned it to Subic Bay.

2 June 1969 SH-3 helicopters from USS Kearsarge (CVS-33) join search and rescue operations over the stern section of USS Frank E. Evans, as USS Everett F. Larson (DD-830) stands ready to offer assistance (at right). NH 98649

She closed out her Vietnam service with Operation End Sweep off Haiphong in 1973. During the six months of End Sweep, 10 ocean minesweepers, 9 amphibious ships, 6 fleet tugs, 3 salvage ships, and 19 destroyer types operated in RADM Brian McCauley’s Task Force 78, sweeping hundreds of the aircraft-laid mines.

By 1973, she was one of 25 of her class still in Navy service but her days were numbered.

Jane’s 1973-74 listing, in which the class is dubbed the Apache class. Note that the list includes the Abnaki-class half-sisters as well.


With a final scoresheet that would include three battle stars for World War II service, two for Korea, and seven for Vietnam, Tawasa was decommissioned and struck from the Navy list on April Fool’s Day 1975. She was sold for scrapping the following August.

There has not been a second Tawasa on the Navy List.

Much of her logs and photos are in the National Archives.

As for the rest of her sisters, many continued in U.S. Navy service until as late as the 1970s when they were either sunk as targets or scrapped. A number went as military aid to overseas allies in Mexico, Colombia, the Dominican Republic, Indonesia, and elsewhere. One sister, USS Apache (ATF-67) who served as the support tender for the bathysphere Trieste, was transferred in 1974 to Taiwan and continues to serve as ROCS Ta Wan (ATF-551). Added to this is USS Pinto (AT-90), which has been in Peru as BAP Guardian Rios (ARB-123), and USS Sioux (AT-75), which lingers as the Turkish Navy’s Gazal (A-587).

The final Abnaki-class half-sister in the Navy’s inventory, ex-USS Paiute (ATF-159), was stricken in 1995 after 44 years of service spanning WWII, Korea, Vietnam, and the First Gulf War, then scrapped in October 2003 at Portsmouth.

The legacy of U.S. Navy fleet tugs is kept alive by NAFTS, the National Association of Fleet Tug Sailors. The only Navy tug museum ship is the former ATA-170-class auxiliary tug USS Wampanoag/USCG Comanche, which will be opened to the public in the coming months.

When it comes to Betty, the National Museum of the U.S. Navy has an inert casing on display, noting, “After tests at sea and in the Nevada desert, the Navy soon determined that the Mk 90 was not a practical weapon and retired the system in 1959.”

Ships are more than steel
and wood
And heart of burning coal,
For those who sail upon
them know
That some ships have a

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One comment

  • Thanks for the info on the USS Tawasa ATF-92. I was part of the last crew for her last 16 months as a radioman.
    The ship was decommissioned a little over a week after I got off the ship. We towed a lot of the mothballed fleet from San Diego to Bremerton that last year and had some adventures at sea along the way.

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