Skipjack-class submarine

USS Skipjack
Class overview
Builders:	General Dynamics Electric Boat Mare Island Naval Shipyard Ingalls Shipbuilding Newport News Shipbuilding
Operators:	United States Navy
Preceded by:	Skate-class submarine
Succeeded by:	Thresher-class submarine
Built:	1956–1961
In commission:	1959–1990
Completed:	6
Lost:	1
Retired:	5
General characteristics
Type:	Nuclear-powered fast attack submarine
Displacement:	Surfaced: 3075 tons (3124 t) Submerged: 3513 tons (3600 t)[1]
Length:	251.7 ft (77 m)
Beam:	31.5 ft (9.65 m)
Propulsion:	1 S5W reactor, geared steam turbines (15,000 shp (11,000 kW)), 1 shaft[1]
Speed:	15 knots (28 km/h; 17 mph) surfaced 33 knots (61 km/h; 38 mph) submerged[2]
Range:	unlimited except by food.
Test depth:	700 ft (210 m)[1]
Complement:	93
Armament:	6 × 21 in (533 mm) torpedo tubes (bow) 24 × Mark 37 torpedoes, Mark 14 torpedoes, Mark 16 torpedoes, Mark 45 ASTOR nuclear torpedoes, and/or Mark 48 torpedoes.

The Skipjack class was a class of United States Navy nuclear submarines (SSNs) that entered service in 1959-61. This class was named after its lead ship, USS Skipjack. The new class introduced the teardrop hull and the S5W reactor to U.S. nuclear submarines.^[1][2] The Skipjacks were the fastest U.S. nuclear submarines until the Los Angeles-class submarines, the first of which entered service in 1974.

Design

Profile, USS Skipjack

The Skipjacks' design was based on the USS Albacore's high-speed hull design. The hull and innovative internal arrangement were similar to the diesel-powered Barbel class that were built concurrently. The design of the Skipjacks was very different from the Skate-class submarines that preceded the Skipjacks. Unlike the Skates, this new design was maximized for underwater speed by fully streamlining the hull like a blimp. This required a single screw aft of the rudders and stern planes. Adoption of a single screw was a matter of considerable debate and analysis within the Navy, as two shafts offered redundancy and improved maneuverability.^[3] The so-called "body-of-revolution hull" reduced her surface sea-keeping, but was essential for underwater performance. Also like Albacore, the Skipjacks used HY-80 high-strength steel, with a yield strength of 80,000 psi (550 MPa), although this was not initially used to increase the diving depth relative to other US submarines. HY-80 remained the standard submarine steel through the Los Angeles class.^[4]

Control room of Skipjack class; the bow is at the top.

Another Barbel-like innovation was the combination of the conning tower, control room, and attack center in one space. This was continued in all subsequent US nuclear submarines. Combining the functions in one space was facilitated by the adoption of "push-button" ballast control, another feature of Albacore.^[3] Previous designs had routed the trim system piping through the control room, where the valves were manually operated. The "push-button" system used hydraulic operators on each valve, remotely electrically operated (actually via toggle switches) from the control room. This greatly conserved control room space and reduced the time required to conduct trim operations. The overall layout made coordination of the weapons and ship control systems easier during combat operations.

Cutaway drawing of Skipjack class1:
1. Sonar arrays
2. Torpedo room
3. Operations compartment
4. Reactor compartment
5. Auxiliary machinery space
6. Engine room

Much of the overall internal arrangement was continued in the subsequent Thresher- and Sturgeon-class submarines. The Skipjacks' five compartments were called the Torpedo Room, Operations Compartment, Reactor Compartment, Auxiliary Machinery Space (AMS), and Engine Room. With the addition of a missile compartment, the arrangement of the first 41 US nuclear-powered ballistic missile submarines (SSBNs) was similar. The design was primarily single-hull, with a double hull around the torpedo room and AMS for ballast tanks. The design was improved on the Threshers, the one-off Tullibee, and subsequent attack submarines by relocating the torpedo room into the operations compartment via angled midships torpedo tubes to make room for a large sonar sphere in the bow. The George Washington class, the first SSBNs, were derived from the Skipjacks, with USS George Washington (SSBN-598) rebuilt from the incomplete first Scorpion. The hull of Scorpion was laid down twice, as the original hull was redesigned to become the George Washington. Also, the material for building Scamp was diverted into building Theodore Roosevelt, which delayed Scamp's progress.

The bow planes were moved to the massive sail to cut down on flow-induced noise near the bow sonar arrays. They were known as sail planes or fairwater planes. The Skipjacks were the first class built with sail planes; they were later backfitted on the Barbels. This design feature would be repeated on all U.S. nuclear submarines until the improved Los Angeles-class submarine, the first of which was launched in 1988. The small "turtleback" behind the sail was the exhaust piping of the auxiliary diesel generator.

The Skipjacks also introduced the S5W reactor to U.S. nuclear submarines. It was known as ASFR (Advanced Submarine Fleet Reactor) during development.^[5] The S5W was used on 98 U.S. nuclear submarines of 8 classes and the first British nuclear submarine, HMS Dreadnought, making it the most-used US Navy reactor design to date.

Service

Skipjack was authorized in the FY 1956 new construction program and commissioned in April 1959. Each hull cost around $40 million. Skipjack was certified as the "world's fastest submarine" after initial sea trials in March 1959, although the actual speed attained was classified. The Skipjacks remained the fastest US nuclear-powered submarines until the first of the Los Angeles class entered service in 1974. This was due to the increased size of the Thresher and Sturgeon classes, which retained Skipjack's S5W power plant, plus the introduction of the skewback screw, which was quiet but mechanically inefficient.^[6] The Skipjacks saw service during the Vietnam War and most of the Cold War. The Skipjack-class submarines were withdrawn from service in the late 1980s and early 1990s except for Scorpion, which sank on 5 June 1968 southwest of the Azores while returning from a Mediterranean deployment, with all 99 crewmembers lost.^[7]

Ships in class

The gap in the hull-number sequence was taken by the two one-of-a-kind submarines USS Triton (SSRN-586) and USS Halibut (SSGN-587).

References

• Gardiner, Robert and Chumbley, Stephen, Conway's All the World's Fighting Ships 1947-1995, London: Conway Maritime Press, 1995. ISBN 1-55750-132-7.
• Hutchinson, Robert, Jane's Submarines, War Beneath The Waves, From 1776 To The Present Day, Harper Paperbacks, 2005. ISBN 0-06081-900-6.
• Polmar, Norman (2004). Cold War Submarines: The Design and Construction of U.S. and Soviet Submarines, 1945-2001. Dulles: Brassey's. ISBN 978-1-57488-594-1.

External links

• NavSource.org SSN photo gallery index
• On Eternal Patrol USS Scorpion page

See also

Wikimedia Commons has media related to Skipjack class submarines.

• List of submarines of the United States Navy
• List of submarine classes of the United States Navy
• List of lost United States submarines