Aggressive-class minesweeper

The Aggressive-class minesweepers are a class of US-built minesweepers. They are designated as MSO (Mine Sweeper Ocean), distinguishing them from the smaller coastal MSCs and inshore MSIs. Besides the US Navy, this class of vessels has also been used by the Belgian Navy and the Norwegian Navy, among others.

USS Constant (MSO-427) in 1988
Class overview
NameAggressive class
Operators
SubclassesOnversaagd class
In commission1953–Present
Completed53
Active1
Retired52
Preserved2
General characteristics
TypeMinesweeper
Displacement853 tons (full load)
Length172 ft (52 m)
Beam35 ft (11 m)
Draft10 ft (3 m)
Propulsion
  • 4 × aluminum block Waukesha diesels, 2,400 bhp (1,800 kW)
  • 2 × shafts
  • 2 × controllable pitch propellers
Speed14 knots (26 km/h; 16 mph)
Complement7 officers, 70 enlisted
Sensors and
processing systems
AN/SQQ-14 mine hunting sonar
Armament

Background

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Minesweeping, or the disposal of naval mines, by these vessels is performed in different ways:

  • Sweeping proper, with an underwater cable cutting the mooring cables of moored mines. The mines then come to the surface and are destroyed by gunfire.
  • Acoustic sweeping, with a towed device producing noise to trigger acoustic mines.
  • Magnetic sweeping, with a towed device producing a magnetic field to trigger magnetic mines. To protect the minesweeper itself against magnetic mines, the hull and superstructure of the ship are made of wood. Other components are made of non-magnetic materials, and any magnetic materials are strictly controlled.

Construction and disposition

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Of the 53 constructed for the United States Navy, 10 were built at Higgins Corp., New Orleans, Louisiana, 9 at J.M. Martinac Shipbuilding Corp., Tacoma, Washington, 8 at Wilmington Boat Works Inc., Wilmington, California, 6 at Luders Marine Construction Co. of Stamford, Connecticut, 4 at Broward Marine Inc, Fort Lauderdale, Florida, 4 at Martinolich Shipbuilding Co., San Diego, California, 3 at Burger Boat Company, Manitowoc, Wisconsin, 3 at Colberg Boat Works, Stockton, California, 2 at Fulton Shipyard, Antioch, California, 2 at Norfolk Naval Shipyard and 2 at Seattle Shipbuilding and Drydocking Co., Seattle, Washington.

33 of the class were decommissioned before the mid-1970s. Four ex-USN ships were sold to the Republic of China Navy 1994 and re-classed as Yung Yang-class minesweepers. They were still in active service in 2012. USS Implicit was decommissioned 30 September 1994 in Tacoma, Washington and was the last Aggressive-class minesweeper in US Navy active service.

Units

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Ship Name Hull no. Builder Commission–
Decommission
Fate Link
Aggressive[1] 422 Luders Marine Construction Co. of Stamford, Connecticut 1953–1971 Sold for scrap 1980
Avenge 423 Luders Marine Construction Co. of Stamford, Connecticut 1954-1970 Destroyed by fire, sold for scrapping 1969
Bold[2] 424 Norfolk Naval Shipyard 1953-1971 Sold for scrap 1981
Bulwark[3] 425 Norfolk Naval Shipyard 1953-1971 Sold for scrap 1980
Conflict[4] 426 Fulton Shipyard, Antioch, California 1954-1973 Sold for scrap 1973
Constant 427 Fulton Shipyard, Antioch, California 1954-1992 Sold for scrap 2001 Naval Vessel Register
428 - 431 were US Dash-class minesweepers
Dynamic 432 Colberg Boat Works, Stockton, California 1953-1971 Sold or loaned to Spain as Guadalete M41, 1971. Naval Vessel Register
Engage 433 Colberg Boat Works, Stockton, California 1953-1991 Scrapped 2002 Naval Vessel Register
Embattle 434 Colberg Boat Works, Stockton, California 1954-1972 Sold to be scrapped 1976, privately held until scrapped by USACE in 1993. Naval Vessel Register
Endurance 435 J. M. Martinac Shipbuilding Corp., Tacoma, Washington 1954-1972 Sold for scrap 1973 Naval Vessel Register
Energy 436 J. M. Martinac Shipbuilding Corp., Tacoma, Washington 1954-1972 Loaned to Philippines 1972
Sold for scrap 1977
Naval Vessel Register
Enhance 437 Martinolich Shipbuilding Co., San Diego, California 1955-1970
1971-1991
Sold for scrap 2000 Naval Vessel Register
Esteem 438 Martinolich Shipbuilding Co., San Diego, California 1955-1970
1971-1991
Sold for scrap 2000 Naval Vessel Register
Excel 439 Higgins Corp., New Orleans, Louisiana 1955-1992 Sold for scrap 2000 Naval Vessel Register
Exploit 440 Higgins Corp., New Orleans, Louisiana 1954-1993 Sold for scrap 2002 Naval Vessel Register
Exultant 441 Higgins Corp., New Orleans, Louisiana 1954-1993 Sold for scrap 2002 Naval Vessel Register
Fearless 442 Higgins Corp., New Orleans, Louisiana 1954-1990 Sold for scrap 1992 Naval Vessel Register
Fidelity 443 Higgins Corp., New Orleans, Louisiana 1955-1989 Sold for scrap 1990 Naval Vessel Register
Firm 444 J. M. Martinac Shipbuilding Corp., Tacoma, Washington 1954-1972 Loaned to Philippines 1972
Scrapped 1977
Naval Vessel Register
Force 445 J. M. Martinac Shipbuilding Corp., Tacoma, Washington 1955-1973 Sunk after a fire Naval Vessel Register
Fortify 446 Seattle Shipbuilding and Drydocking Co., Seattle, Washington 1954-1992 Scrapped 2002 Naval Vessel Register
Guide 447 Seattle Shipbuilding and Drydocking Co., Seattle, Washington 1955-1972 Sold for scrap 1973 Naval Vessel Register
Illusive 448 Martinolich Shipbuilding Co., San Diego, California 1953-1990 Sold for scrap 1993 Naval Vessel Register
Impervious 449 Martinolich Shipbuilding Co., San Diego, California 1954-1991 Scrapped 2002 Naval Vessel Register
450 - 454 built at Bellingham Shipyards Co., Bellingham, Washington for France, not necessarily Aggressive-class ships.
Implicit 455 Wilmington Boat Works Inc., Wilmington, California 1954-1994 Sold to Taiwan 1994 Naval Vessel Register
Inflict 456 Wilmington Boat Works Inc., Wilmington, California 1954-1990 Sold for scrap 1992 Naval Vessel Register
Loyalty 457 Wilmington Boat Works Inc., Wilmington, California 1954-1972 Sold for scrap 1973 Naval Vessel Register
Lucid 458 Higgins Corp., New Orleans, Louisiana 1955-1970 Sold for scrap 1976
Currently being restored by the Stockton Historical Maritime Museum as a museum ship
Naval Vessel Register
Nimble 459 Higgins Corp., New Orleans, Louisiana 1955-1970 Sold for scrap 1981 Naval Vessel Register
Notable 460 Higgins Corp., New Orleans, Louisiana 1955-1970 Sold for scrap 1971 Naval Vessel Register
Observer 461 Higgins Corp., New Orleans, Louisiana 1955-1972 Sold for scrap 1979 Naval Vessel Register
Pinnacle 462 Higgins Corp., New Orleans, Louisiana 1955-1970 Sold for scrap 1978 Naval Vessel Register
Pivot 463 Wilmington Boat Works Inc., Wilmington, California 1954-1971 Initially loaned then sold to Spain as Guadalmedina M42, 1974. Decommissioned by Spain 2001. Naval Vessel Register
Pluck 464 Wilmington Boat Works Inc., Wilmington, California 1954-1990 Sold for scrap 1992 Naval Vessel Register
Prestige 465 Wilmington Boat Works Inc., Wilmington, California 1954-1958 Grounded and sunk, 1958 in the Naruto Strait
Prime 466 Wilmington Boat Works Inc., Wilmington, California 1954-1970 Sold for scrap 1976 Naval Vessel Register
Reaper 467 Wilmington Boat Works Inc., Wilmington, California 1954-1972 Sold for scrap 1976 Naval Vessel Register
Rival 468 Luders Marine Construction Co. of Stamford, Connecticut 1954-1970 Sold for scrap 1971 Naval Vessel Register
Sagacity 469 Luders Marine Construction Co. of Stamford, Connecticut 1955-1970 Grounded at Charleston Harbor then sold for scrap 1970.
Salute 470 Luders Marine Construction Co. of Stamford, Connecticut 1955-1970 Sold for scrap 1971 Naval Vessel Register
Skill 471 Luders Marine Construction Co. of Stamford, Connecticut 1950-1970 Sold for scrap 1979, scrapped 1983. Naval Vessel Register
Valor 472 Burger Boat Company, Manitowoc, Wisconsin 1954-1970 Sold for scrap 1971 Naval Vessel Register
Vigor 473 Burger Boat Company, Manitowoc, Wisconsin 1954-1972 Sold to Spain as Guadiana M44, 1972. Scrapped by Spain after 1999. Naval Vessel Register
Vital 474 Burger Boat Company, Manitowoc, Wisconsin 1955-1972 Sold for scrap 1979 Naval Vessel Register
475 - 487 built for France, Portugal, Spain, Belgium and the Netherlands, not necessarily Aggressive-class ships.
Conquest 488 J. M. Martinac Shipbuilding Corp., Tacoma, Washington 1955-1970
1971-1994
Sold to Taiwan 1994 and decommissioned in 2020. Naval Vessel Register
Gallant 489 J. M. Martinac Shipbuilding Corp., Tacoma, Washington 1955-1994 Sold to Taiwan 1994 and decommissioned in 2013. Naval Vessel Register
Leader 490 J. M. Martinac Shipbuilding Corp., Tacoma, Washington 1955-1970
1971-1991/92
Sold for scrap 1994 Naval Vessel Register
Persistent 491 J. M. Martinac Shipbuilding Corp., Tacoma, Washington 1956-1971 Initially loaned in 1971 then sold to Spain as Guadalquivir M43 Naval Vessel Register
Pledge[5] 492 J. M. Martinac Shipbuilding Corp., Tacoma, Washington 1956-1994 Sold to Taiwan 1994 and decommissioned 2021. Naval Vessel Register
Stalwart 493 Broward Marine Inc, Fort Lauderdale, Florida 1956-1966 Caught fire pier side at San Juan, Puerto Rico, sunk 1966. Later raised and sunk as an artificial reef.
Sturdy 494 Broward Marine Inc, Fort Lauderdale, Florida 1957-1971 Sold for scrap 1978 Naval Vessel Register
Swerve 495 Broward Marine Inc, Fort Lauderdale, Florida 1957-1971 Sold for scrap 1978 Naval Vessel Register
Venture [6] 496 Broward Marine Inc, Fort Lauderdale, Florida 1958-1971 Sold for scrap 1978
MSO-497 497 Cancelled, never built

See also

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References

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