The Skate-class submarines were the United States Navy's first production run of nuclear-powered submarines. They were an evolution of the Tang class in everything except their propulsion plants, which were based on the operational prototype USS Nautilus. The four Skate class boats re-introduced stern torpedo tubes. Although among the smallest nuclear-powered attack submarines ever built, the Skate class served for many years, with the last being decommissioned in 1989. USS Skate was the first submarine to surface at the North Pole, on 17 March 1959.

Quick Facts Class overview, General characteristics ...

USS Skate with an ice pack behind her
Class overview
Name	Skate class
Builders	General Dynamics Electric Boat Portsmouth Naval Shipyard Mare Island Naval Shipyard
Operators	United States Navy
Preceded by	USS Nautilus (SSN-571) USS Seawolf (SSN-575) Tang class USS Darter (SS-576)
Succeeded by	Skipjack class Barbel class
Built	1955–1959
In commission	1957–1989
Completed	4
Retired	4
General characteristics
Type	Nuclear submarine
Displacement	2,250 long tons (2,290 t) surfaced 2,850 long tons (2,900 t) submerged
Length	267 ft 7 in (81.56 m)
Beam	25 ft (7.6 m)
Draft	21 ft 3 in (6.48 m)
Propulsion	S3W nuclear reactor in S3W or S4W plant, geared steam turbines, two shafts, 6,600 shp (4,900 kW)[1]
Speed	18 kn (33 km/h; 21 mph) surfaced 22 kn (41 km/h; 25 mph) submerged
Test depth	700 ft (210 m)
Complement	84 officers and men
Armament	8 × 21 inch (533 mm) torpedo tubes (6 forward, 2 aft) 22 torpedoes (18 forward, 4 aft)

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Skate and Sargo were built with the S3W reactor,^[2][3] Swordfish and Seadragon also had the S3W reactor in the S4W reactor plant (same machinery in an alternate arrangement).^[4][5]

The Skate class were designed under project SCB 121 as economical production nuclear-powered submarines (SSNs), and thus were smaller and more austere than their ground-breaking predecessor Nautilus, whose high cost had raised concerns. They were designed before Nautilus demonstrated the advantages of sustained high underwater speed, thus their designed speed was about the maximum speed of the conventional Tang class, which had a similar displacement to the Skates. Their S3W reactor was a scaled-down version of Nautilus' S2W reactor with about half the power output; it was known as SFR (Submarine Fleet Reactor) during development. A slightly modified version known as S4W powered the second pair of Skate-class boats. Unfortunately, scaling down the reactor did not reduce the weight of reactor shielding proportionally, and it was eventually realized that further downsizing was impractical. In the late 1950s it was hoped that the nuclear-powered aircraft program would develop reactors suitable for very small SSNs, but the program was unsuccessful.^[6] Their armament was the same as the Tangs, six bow and two stern 21 inch (533 mm) torpedo tubes. Like the Tangs, the stern tubes had no ejection pump, and could only be used for swim-out weapons such as the Mark 37 ASW homing torpedo. The quest for a high submerged speed and improved sonar led to the subsequent Skipjack and Thresher classes becoming the model for further development.^{[citation needed]}

Skate was notable as the first submarine to surface at the North Pole, on 17 March 1959. A previous attempt in 1958 had resulted in no suitable place found for surfacing near the Pole. Sargo and Seadragon also conducted significant polar operations in their careers. This class was the most suited for ice breakthrough attempts until the Sturgeon class, with fairwater planes that could be rotated vertically, entered service beginning in 1967. After 25–30 years each of successful service, mostly out of Pearl Harbor, the class was retired in the 1980s and disposed of through the Navy's nuclear Ship-Submarine Recycling Program.^{[citation needed]}