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NavSource Online: Mine Warfare Vessel Photo Archive


Courtesy of Arie van Mazijk

Call sign:
Papa - Alpha - Juliet - Papa

AM-485 was built for the Netherlands

AM-480 Class Fleet Minesweeper:

  • Laid down 17 February 1952 as AM-485 by the Peterson Builders Inc., Sturgeon Bay, WI
  • Launched, 22 August 1953
  • Completed 22 November 1954 and transferred to the Netherlands and named HMNLS Onverdroten (M 889)
  • Reclassified by U. S. Navy as an Ocean Minesweeper, MSO-485, 7 February 1955
  • Reclassified by The Netherlands as A-859
  • Sold 18 September 1984 to W. Mantel of Amsterdam, Holland
  • Scrapped.


  • Displacement 750 t.
  • Length 171'
  • Beam 35'
  • Draft 10' 4"
  • Speed 15 kts.
  • Complement 39
  • Armament: One 40mm mount and two .50 cal. machine guns
  • Propulsion 1,600shp General Motors diesel enginess, two shafts.
    Click on thumbnail
    for full size image
    Size Image Description Source
    AM-484 55k Minesweeper hulls AM-483, 484, 485 for the Netherlands in the background. In the foreground is the last American-made side-wheeler still afloat in the U.S. and used as a floating warehouse, Restored and now serves as a museum in Sandusky, Ohio
    Photo courtesy Peterson Builders
    Mercuur Museum Website
    Onverdroten (M 889)
    MSO-484 64k 30 April 1955
    Ponta Delgada, Azores
    Brouwershaven (M 858), ex-MSC-150, Onvermoeid (M 887), ex-MSO-484) and Onverdroten in dress ship for Queen's Day still wearing their U.S. Navy hull numbers
    Arie van Mazijk
    MSO-485 68k Still wearing her U.S. Navy hull number
    MSO-485 76k
    MSO-485 90k Crew photo
    MSO-485 132k c. 1955
    Arriving in Den Helder, Holland
    MSO-485 212k .
    MSO-485 38k
    Onverdroten 54k Royal Dutch Navy photo Mercuur Museum Website
    Onverdroten 123k Oostende, Belgium
    MSO-485 61k Moored outboard of an unidentified English Frigate Arie van Mazijk
    MSO-485 65k .
    MSO-485 47k
    MSO-485 67k
    MSO-485 48k 1 February 1956
    Den Helder, Holland
    Moored aft of Onvervaard (M 888), ex-MSO-482
    MSO-485 121k c. 1957
    Royal Netherlands Navy photo from the 1958/1959 edition of Jane's Fighting Ships
    Robert Hurst
    MSO-485 212k c. 1958
    Oostende, Belgium
    Gilbert Gyssels
    MSO-485 79k c. 1964
    Photo by Stefan Terzibaschitsch from the 1964/1965 edition of Jane's Fighting Ships
    Robert Hurst
    Onverdroten (A 859)
    MSO-485 44k . Arie van Mazijk
    MSO-485 47
    MSO-485 107k Undated post card showing Onvermoeid (A 857), Onbevreesd (A 855) and Onverdroten laid up in the Reserve Fleet
    MSO-485 8k . Tommy Trampp

    There is no DANFS history available for MSO-485
    Additional Resources and Web Sites of Interest
    102 Minesweepers (MSO) Oceangoing Minesweepers
    Naval Minewarfare Association
    Association of Minemen
    Back to the Main Photo Index Back to the Mine Warfare Ship Photo Index Back to the Ocean Minesweeper (MSO) Photo Index

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    This page created and maintained by Joseph M. Radigan
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