USS Mackerel (SST-1), originally known as USS T-1 (SST-1), was the lead ship of the T-1-class

T-1 class submarine

The T-1 class submarines were a pair of submarines built for the United States Navy in the early 1950s for use in training submarine personnel and testing submarine equipment. Both submarines of the class served in these roles for over 19 years....

 of training submarine

Submarine

A submarine is a watercraft capable of independent operation below the surface of the water. It differs from a submersible, which has more limited underwater capability...

s. She was the second submarine of the United States Navy

United States Navy

The United States Navy is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. The U.S. Navy is the largest in the world; its battle fleet tonnage is greater than that of the next 13 largest navies combined. The U.S...

 named for the mackerel

Mackerel

Mackerel is a common name applied to a number of different species of fish, mostly, but not exclusively, from the family Scombridae. They may be found in all tropical and temperate seas. Most live offshore in the oceanic environment but a few, like the Spanish mackerel , enter bays and can be...

, a common food and sport fish

Fish

Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...

, and was in service from 1953 to 1973. She was one of the smallest operational submarines ever built for the U.S. Navy.

Construction and commissioning

T-1 was originally planned as an experimental auxiliary submarine with hull number

Hull classification symbol

The United States Navy, United States Coast Guard, and United States National Oceanic and Atmospheric Administration use hull classification symbols to identify their ship types and each individual ship within each type...

 AGSS-570, but she was redesignated as a training submarine (SST-1) and her hull number was changed to SST-1. She was laid down on 1 April 1952, at the Electric Boat

Electric boat

While a significant majority of water vessels are powered by diesel engines, with sail power and gasoline engines also remaining popular, boats powered by electricity have been used for over 120 years. Electric boats were very popular from the 1880s until the 1920s, when the internal combustion...

 Division of General Dynamics

General Dynamics

General Dynamics Corporation is a U.S. defense conglomerate formed by mergers and divestitures, and as of 2008 it is the fifth largest defense contractor in the world. Its headquarters are in West Falls Church , unincorporated Fairfax County, Virginia, in the Falls Church area.The company has...

 Corporation at Groton

Groton, Connecticut

Groton is a town located on the Thames River in New London County, Connecticut, United States. The population was 39,907 at the 2000 census....

, Connecticut

Connecticut

Connecticut is a state in the New England region of the northeastern United States. It is bordered by Rhode Island to the east, Massachusetts to the north, and the state of New York to the west and the south .Connecticut is named for the Connecticut River, the major U.S. river that approximately...

. She was launched

Ship naming and launching

The ceremonies involved in naming and launching naval ships are based in traditions thousands of years old.-Methods of launch:There are three principal methods of conveying a new ship from building site to water, only two of which are called "launching." The oldest, most familiar, and most widely...

 on 17 July 1953, sponsored by Mrs. Charles R. Muir, and placed in non-commissioned

Ship commissioning

Ship commissioning is the act or ceremony of placing a ship in active service, and may be regarded as a particular application of the general concepts and practices of project commissioning. The term is most commonly applied to the placing of a warship in active duty with its country's military...

 service as USS T-1 on 9 October 1953, with Lieutenant

Lieutenant

A lieutenant is a junior commissioned officer in many nations' armed forces. Typically, the rank of lieutenant in naval usage, while still a junior officer rank, is senior to the army rank...

 J. M. Snyder, Jr., in command.

Training, target, and equipment testing services, 1954–1966

After completing sea trials in the New London

New London, Connecticut

New London is a seaport city and a port of entry on the northeast coast of the United States.It is located at the mouth of the Thames River in New London County, southeastern Connecticut....

, and Massachusetts Bay

Massachusetts Bay

The Massachusetts Bay, also called Mass Bay, is one of the largest bays of the Atlantic Ocean which forms the distinctive shape of the coastline of the U.S. state of Massachusetts. Its waters extend 65 miles into the Atlantic Ocean. Massachusetts Bay includes the Boston Harbor, Dorchester Bay,...

 areas, T-1 departed in February 1954 for Key West

Key West, Florida

Key West is a city in Monroe County, Florida, United States. The city encompasses the island of Key West, the part of Stock Island north of U.S. 1 , Sigsbee Park , Fleming Key , and Sunset Key...

, Florida

Florida

Florida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...

. Arriving at Key West, she commenced operations with submarine and antisubmarine forces in the areas of southern Florida and Guantanamo Bay, Cuba

Cuba

The Republic of Cuba is an island nation in the Caribbean. The nation of Cuba consists of the main island of Cuba, the Isla de la Juventud, and several archipelagos. Havana is the largest city in Cuba and the country's capital. Santiago de Cuba is the second largest city...

, providing services to the Fleet Training Group working up recently constructed and recently overhauled antisubmarine warships.

On 15 July 1956, T-1 was renamed Mackerel, but retained her hull number, SST-1.

Following her renaming, Mackerel participated in fleet exercises off the United States East Coast, mainly conducting training assignments and providing services as a target, including some for the Fleet Sonar School

Fleet Sonar School

The Fleet Sonar School was a United States Navy facility in Key West, Florida for the training of Service personnel in Sonar techniques and equipment, and Anti-submarine warfare....

 at Key West. She also made several cruises testing new equipment for submarines. On 2 April 1957, she departed Key West on a special sound-damping project during a voyage to Annapolis

Annapolis, Maryland

Annapolis is the capital of the U.S. state of Maryland, as well as the county seat of Anne Arundel County. It had a population of 38,394 at the 2010 census and is situated on the Chesapeake Bay at the mouth of the Severn River, south of Baltimore and about east of Washington, D.C. Annapolis is...

, Maryland

Maryland

Maryland is a U.S. state located in the Mid Atlantic region of the United States, bordering Virginia, West Virginia, and the District of Columbia to its south and west; Pennsylvania to its north; and Delaware to its east...

. She conducted more training and target cruises into the early 1960s.

In 1963, Mackerel conducted the first of her test and evaluation voyages. Departing Key West on 8 July 1963, she sailed to the British West Indies where she tested acoustical developments in submarine hulls

Hull (watercraft)

A hull is the watertight body of a ship or boat. Above the hull is the superstructure and/or deckhouse, where present. The line where the hull meets the water surface is called the waterline.The structure of the hull varies depending on the vessel type...

 for a two‑week period in waters near the British West Indies

British West Indies

The British West Indies was a term used to describe the islands in and around the Caribbean that were part of the British Empire The term was sometimes used to include British Honduras and British Guiana, even though these territories are not geographically part of the Caribbean...

. In addition to resumption of her routine duties, she again operated in the West Indies in February 1964, again performing tasks related to evaluating submarine-hull acoustic developments.

From 7 March 1965 to 4 April 1965, Mackerel joined her sister ship

Sister ship

A sister ship is a ship of the same class as, or of virtually identical design to, another ship. Such vessels share a near-identical hull and superstructure layout, similar displacement, and roughly comparable features and equipment...

  and attack submarines , , and , along with a task force under Commander, Mine Force, in participating in mine warfare

Naval mine

A naval mine is a self-contained explosive device placed in water to destroy surface ships or submarines. Unlike depth charges, mines are deposited and left to wait until they are triggered by the approach of, or contact with, an enemy vessel...

 maneuvers.

Testing equipment for NR-1, 1966-1967

During May and June 1966, Electric Boat installed special equipment in Mackerel at Groton. Mackerel then transited south to Key West, arriving there on 26 June 1966. At Key West, she conducted experimental work during the rest of 1966 and in early 1967 to acquire data to be used in the development of future U.S. Navy submarines. She evaluated equipment intended for the NR-1 Deep Submergence Craft

NR-1 Deep Submergence Craft

The Deep Submergence Vessel NR-1 was a unique United States Navy nuclear-powered ocean engineering and research submarine. It was built by the Electric Boat Division of General Dynamics at Groton, Connecticut. It was launched on January 25, 1969, completed its initial sea trials August 19, 1969,...

, including keel-mounted wheels for rolling over the ocean floor, thrusters, external television cameras, a manipulator arm, and experimental sonar

Sonar

Sonar is a technique that uses sound propagation to navigate, communicate with or detect other vessels...

. Mackerel "bottomed" -- deliberately settled on the sea floor—some 225 times during the nine-month evaluation period. She completed this assignment during March 1967, after which she had some of her special equipment removed. At the same time she undertook the additional task of providing shiphandling training for submarine force junior officers. During June and July 1967, while Mackerel in drydock at Key West, additional special project equipment was removed from her.

Target services, 1967-1973

Mackerel resumed operations at Key West in 1967, running submerged to serve as a target for vessels used to train sonar operators at the Fleet Sonar School; at the same time, she undertook the additional task of providing shiphandling training for submarine force junior officers. She also acted as a target for surface and air antisubmarine warfare forces practicing off the Florida coast and in the Caribbean

Caribbean

The Caribbean is a crescent-shaped group of islands more than 2,000 miles long separating the Gulf of Mexico and the Caribbean Sea, to the west and south, from the Atlantic Ocean, to the east and north...

 during the late 1960s and early 1970s. In 1971 and 1972, she provided target and training services for antisubmarine warfare units of the United States Atlantic Fleet in the Key West and the Mayport

Naval Station Mayport

Naval Station Mayport is a major United States Navy base in Jacksonville, Florida. It contains a military airfield with one asphalt paved runway measuring 8,001 x 200 ft. ....

/Jacksonville

Jacksonville, Florida

Jacksonville is the largest city in the U.S. state of Florida in terms of both population and land area, and the largest city by area in the contiguous United States. It is the county seat of Duval County, with which the city government consolidated in 1968...

, Florida, operating areas. Apparently, her non-commissioned service period ended when she was finally commissioned

Ship commissioning

Ship commissioning is the act or ceremony of placing a ship in active service, and may be regarded as a particular application of the general concepts and practices of project commissioning. The term is most commonly applied to the placing of a warship in active duty with its country's military...

 sometime in 1971.

Mackerel made her last dive on 21 July 1972. After that, she remained in service with a reduced crew and conducted junior officer and midshipman

Midshipman

A midshipman is an officer cadet, or a commissioned officer of the lowest rank, in the Royal Navy, United States Navy, and many Commonwealth navies. Commonwealth countries which use the rank include Australia, New Zealand, South Africa, India, Pakistan, Singapore, Sri Lanka and Kenya...

 training on the surface regularly through October 1972. She was taken out of service on 3 January 1973.

Decommissioning and disposal

Mackerel and her sister were decommissioned

Ship decommissioning

To decommission a ship is to terminate her career in service in the armed forces of her nation. A somber occasion, it has little of the elaborate ceremony of ship commissioning, but carries significant tradition....

 on 31 January 1973 in a dual ceremony at Naval Station Key West. Both also were struck from the Naval Vessel Register

Naval Vessel Register

The Naval Vessel Register is the official inventory of ships and service craft in custody of or titled by the United States Navy. It contains information on ships and service craft that make up the official inventory of the Navy from the time a vessel is authorized through its life cycle and...

 that day.

Mackerel was sunk as a target off Puerto Rico

Puerto Rico

Puerto Rico , officially the Commonwealth of Puerto Rico , is an unincorporated territory of the United States, located in the northeastern Caribbean, east of the Dominican Republic and west of both the United States Virgin Islands and the British Virgin Islands.Puerto Rico comprises an...

on 18 October 1978.