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NavSource Online: Mine Warfare Vessel Photo Archive

Pioneer (MSF 105)

Call sign:
November - Alpha - Romeo - November

Pioneer served the Navies of the United States and Mexico.

Auk Class Minesweeper:

  • The first Pioneer was laid down 30 October 1941 by the Pennsylvania Shipyards, Inc., Beaumont, TX
  • Launched 26 July 1942
  • Commissioned USS Pioneer (AM 105), 27 February 1943
  • Decommissioned 8 July 1946 at San Diego, CA
    Naval Vessel Register of 1 January 1949 lists out of commission, in reserve as December 1945
  • Reclassified as a Fleet Minesweeper (Steel Hull), MSF-105, 7 February 1955
  • Struck from the Navy Register 1 July 1972
  • Sold to Mexico 19 September 1972 and renamed ARM Leandro Valle (C 70)
  • Reclassified P-101 and G-01
  • Fate unknown.


  • Displacement 890 t.
  • Length 221' 2"
  • Beam 32'
  • Draft 10' 9"
  • Speed 18.1 kts.
  • Complement 105
  • Armament: One 3"/50 dual purpose gun mount, two 40mm gun mounts, two 20mm gun mounts, two depth charge tracks, and five depth charge projectors
  • Propulsion: Two 1,559shp Busch Sulzer 539 diesel electric engines, Westinghouse reduction gear, two shafts.
    Click on thumbnail
    for full size image
    Size Image Description Source
    Pioneer (AM 105)
    Pioneer 652k 18 February 1943
    Pennsylvania Shipyards, Inc., Beaumont, TX
    U.S. Navy photo
    David Buell
    USS Pioneer (AM 105)
    Pioneer 176k Richard Miller, BMCS, USNR, Ret.
    Pioneer 78k c. 1943 .
    ARM Leandro Valle (P 101)
    Pioneer 55k Namesake: Leandro Valle Martínez (Mexico City, February 27, 1833-Monte de las Cruces, Cuajimalpa de Morelos, June 23, 1861) was a Mexican liberal general, an ally of President Benito Juárez during the War of the Reformation Tommy Trampp
    Photo added 19 March 2020
    Pioneer 78k Mexican Navy Photo Mexican Navy

    Commanding Officers
    01LCDR Howard Boyd Stevens, USN22 February 1943
    02LT Leroy Edward Rogers, Jr., USNR27 August 1943
    03LT Robert L. Cantine, USNR22 September 1945
    04LTJG Isadore David Cohen., USNR4 February 1946
    05ENS Joseph P. Phelan, USNR20 April 1946
    06ENS Timothy Robert Enright, USNR30 May 1946 - 8 July 1946
    Courtesy of Wolfgang Hechler and Ron Reeves

    View the Pioneer (MSF 105)
    DANFS History entry located on the Haze Gray & Underway Website
    Back to the Main Photo Index Back to the Mine Warfare Ship Photo Index Back to the Fleet Minesweeper (MSF) Photo Index

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    This page created and maintained by Joseph M. Radigan
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