fighting ships of the world



THRESHER nuclear powered submarines (1961 - 1967)

Thresher 1963

Permit 1970

Permit 1979

Permit 1990

Flasher 1990

No Name Yard No Builder Laid down Launched Comm Fate
SSN593 Thresher   Portsmouth N Yd, Kittery 28/5/1958 9/7/1960 3/8/1961 foundered 10/4/1963
SSN594 Permit   Mare Island N Yd, Vallejo 16/7/1959 1/7/1961 29/5/1962 stricken 6/1991
SSN595 Plunger   Mare Island N Yd, Vallejo 2/3/1960 9/12/1961 21/11/1962 stricken 2/1990
SSN596 Barb (ex-Pollack) 1079 Ingalls, Pascagoula 9/11/1959 12/2/1962 24/8/1963 stricken 12/1989
SSN603 Pollack (ex-Barb) 534 New York SB, Camden 14/3/1960 17/3/1962 26/5/1964 stricken 3/1989
SSN604 Haddo 535 New York SB, Camden 9/9/1960 18/8/1962 16/12/1964 stricken 6/1991
SSN605 Jack   Portsmouth N Yd, Kittery 16/9/1960 24/4/1963 31/3/1967 stricken 7/1990
SSN606 Tinosa   Portsmouth N Yd, Kittery 24/11/1959 9/12/1961 17/10/1964 stricken 1/1992
SSN607 Dace 1080 Ingalls, Pascagoula 6/6/1960 18/8/1962 4/4/1964 stricken 12/1988
SSN612 Guardfish 539 New York SB, Camden 13/2/1961 15/5/1965 20/12/1966 stricken 2/1992
SSN613 Flasher 158 Electric Boat, Groton 14/4/1961 22/6/1963 22/7/1966 stricken 5/1992
SSN614 Greenling 160 Electric Boat, Groton 15/8/1961 4/4/1964 3/11/1967 stricken 4/1994
SSN615 Gato 162 Electric Boat, Groton 15/12/1961 14/5/1964 25/1/1968 stricken 10/1995
SSN621 Haddock 1081 Ingalls, Pascagoula 24/4/1961 21/5/1966 22/12/1967 stricken 4/1993


Displacement standard, t


Displacement normal, t

SSN593 - 596, 603, 604, 606, 607, 612, 621: 3705 / 4311

SSN605: 3900 / 4470

SSN613 - 615: 3800 / 4242

Length, m

SSN593 - 596, 603, 604, 606, 607, 612, 621: 84.9

SSN605: 90.5

SSN613 - 615: 89.1

Breadth, m


Draught, m


No of shafts


SSN605: 1 (2 propellers)


2 sets General Electric or de Laval geared steam turbines, 1 Westinghouse S5W nuclear reactor

Power, h. p.


Max speed, kts

15 / 28

Fuel, t


Endurance, nm (kts)

practically unlimited


4 - 533 Mk 63 TT (amidships, 23 torpedoes, including 4 SUBROC UUM-44 ASW rockets)


SSN593 - 596, 603 - 607, 612, 621: BPS-5 or BPS-9 or BPS-15 radars, BQQ-2 (BQS-6 + BQR-7) sonar suite, BQS-14 sonar, WLR-1 ECM suite

SSN613 - 615: BPS-5 or BPS-9 or BPS-15 radars, BQQ-5 sonar suite, BQS-14 sonar, WLR-1 ECM suite



Diving depth operational, m



Ship project history: This is the largest class of submarines built by the United States since 1945; officially it was subdivided into Thresher/Permit and Sturgeon classes; the original name-ship, Thresher, was lost on diving trials on 10 April 1963. They combine a stronger hull for deeper diving with an advanced long-range BQQ-2 sonar and its associated SUBROC missile; diving depth is reportedly 400m. Later units were lengthened to permit die installation of a BQQ-5 sonar in place of BQQ-2; the extra space is free flooding, and underwater displacement rises by about 200t to 350t (SSN613-615 and most Sturgeon class submarines); ultimately all of these units will have BQQ-5. All will also ultimately receive the Mk 117 fire control system in place of their current Mk 113, providing facilities for Harpoon anti-ship missile control. However, since SUBROC is an analogue rather than a digital weapon, and Mk 117 is a fully digital fire control system, the long-range ASW capability (except as provided by the Mk 48 torpedo) is being lost. SSN613-615 were, in effect, prototype Sturgeons with heavier machinery, taller fins (6.1m rather than 4.2m or 4.6m), improved safety features ('Sub-safe' programme), and lengthened hulls.

    As officially described in 1979, Thresher class design compromises included a low sail, inadequate numbers of periscopes and antennas, and limited electronics. The reduced sail height was specifically accepted to minimize the speed loss, given the fixed reactor power of the S5W. The SSN637 class was considerably enlarged for a combination of quieting and additional electronics, as well as improved internal arrangements. Presumably the electronics was a combination of sonar signal processing and torpedo control, one control console being required for each wire-guided torpedo.

These submarines were intended primarily for ASW, with a large spherical sonar array filling their bows, and the torpedo battery, reduced to four tubes, moved aft to abreast the fin, firing diagonally from the hull. One advantage of this arrangement was that a large torpedo room could be provided, permitting a relatively easy choice of weapons for each tube. By the late 1060s, the submarine commander had a choice of long ASW torpedoes, nuclear torpedoes (Astor, or Mk 45, now retired), long anti-ship torpedoes, or SUBROC now there are Harpoon (first tested in Permit in 1976) and, very soon, Tomahawk. Unfortunately total weapon capacity was quite small, figures as low as twenty torpedoes in stowage being reported, so that this variety of weapons is very much a mixed blessing. Indeed, one advantage of the adoption of the Mk 48 torpedo was that it can replace both long ASW and long anti-ship weapons, and the Mk 45 was discarded partly because it consumed valuable space but was unlikely to be used in action.

    Since the power plant, the S5W, duplicated that of the earlier Skipjack, and the size of these submarines was much greater (by at least 800t), these ships were considerably slower. There were three attempts within this class id improve propulsion. Jack has contraprops on her single screw, an arrangement never duplicated. Narwhal has a natural convection powerplant (S5G rather than S5W); and Glenard P. Lipscomb had turbo-electric propulsion, both of the last two choices having been made for quietness.

Modernizations: 1970s, all: - BQQ-2 sonar suite; + BQQ-3 (BQS-11 + BQR-7) sonar suite

early 1980s, Permit, Plunger, Barb, Pollack, Dace, Flasher, Haddock; late 1980s, Haddo, Jack, Tinosa, Guardfish, Greenling, Gato: - 4 SUBROC ASW rockets (UUM-44); + 4 Harpoon SSM (UGM-84)

late 1980s, many: - BQQ-3 sonar suite; + BQQ-5 sonar suite

Naval service: Thresher sunk 10/4/1963 during diving tests in 220nm E of Boston.

Haddock 1979

Ivan Gogin, 2015