Please report any broken links or trouble you might come across to the Webmaster. Please take a moment to let us know so that we can correct any problems and make your visit as enjoyable and as informative as possible.

NavSource Online: Amphibious Photo Archive
Contributed by Al Grazevich

USS Portunus (ARC-1)
ex
 USS LSM-275 (1944 - 1951)


International Radio Call Sign:
November - Victor - Golf - Lima
 NVGL
Awards, Citations and Campaign Ribbons


Precedence of awards is from top to bottom, left to right
Top Row - American Campaign Medal
Bottom Row - Asiatic-Pacific Campaign Medal (1) - World War II Victory Medal - National Defense Service Medal

USS Portunus (ARC-1) was transferred to Portugal and renamed NRP Medusa (A5214)
LSM-1 Class Landing Ship Medium:
  • Laid down, 1 August 1944, at Federal Shipbuilding and Drydock Co., Newark, N.J.
  • Launched, 11 September 1944
  • Commissioned USS LSM-275, 6 October 1944, LT. Daniel D. McLeod USNR in command
  • During World War II USS LSM-275 was assigned to the Asiatic-Pacific Theater:
    LSM Flotilla Twelve, LCDR. A. F. Dineen USN (22);
    LSM Group Thirty-Six, LT. V. L. Homer USN;
    LSM Division Seventy-One and participated in the following campaign:

    Asiatic-Pacific Campaign
    Campaign and Dates
    Okinawa Gunto operation
    Assault and occupation of Okinawa Gunto, 2 to 29 April 1945

  • Decommissioned, 21 April 1947, at Terminal Island Navy Yard, San Pedro, CA.
  • Laid up in the Pacific Reserve Fleet
  • Redesignated a Cable Repair Ship, 14 December 1951
  • Converted at Mare Island Naval Shipyard, Vallejo, CA., between 15 January and 18 August 1952
  • Recommissioned, USS Portunus (ARC-1), 2 July 1952, LT. Stanley A. Siebenthal, USN, in command
  • Decommissioned, 30 April 1959, at New York
  • Struck from the Naval Register, 1 May 1959
  • USS LSM-275 earned one battle star for World War II service
  • Transferred, 16 November 1959, under the Military Assistance Program, to Portugal
  • Commissioned into the Portuguese Navy, 18 November 1959 as NRP Medusa (A5214)
  • Transferred, 24 September 1964 to the Arsenal do Alfeite, for modification to a Marine Support Ship
  • After modification the ship was assigned permanently to the Guinea-Bissau Maritime Defense Command, renamed S. Rafael in July 1969
  • Reclassified as a Support Ship for submarines of the "Albacora" class
  • Final Disposition, Disarmed, 2 February 1972, Decommisisoned, 7 January 1976
    Specifications:
    Displacement 520 t.(light), 743 t. (landing) 1,095 t.(fully loaded)
    Length 203' 6" (ovl)
    Beam 34' 6"
    Draft
    light, 3' 6" forward, 7' 8" aft
    fully loaded, 6' 4" forward, 8' 3" aft
    Speed 13.2 kts. (max.), (928 tons displacement)
    Complement
    5 officers
    54 enlisted
    Armament
    one twin bow mounted 40mm gun
    four single 20mm gun mounts
    Vehicle/Boat Capacity 5 medium or 3 heavy tanks, or 6 LVT's, or 9 DUKW's
    Fuel Capacity
    Diesel 1,225 Bbls
    Troop Accommodations
    2 officers
    46 enlisted
    Armor 10-lb. STS splinter shield to gun mounts, pilot house and conning station
    Endurance 4,900 miles @ 12kts.(928 tons displacement)
    Propulsion
    two General Motors (model GM 16-278A, reversible with hydraulic clutch) Diesel engines, direct drive with 1,440 BHP each @ 720rpm
    Ship's Service Generators
     two Diesel-drive 100Kw 450V A.C.
     one Diesel-drive 20Kw 120V D.C.
    twin propellers, 2,800shp
    Click On Image
    For Full Size Image    		 Size Image Description Contributed
    By
    USS LSM-275
    LSM-167 76k USS LSM-275 and USS LSM-167 beached at Okinawa, 7 April 1945. Note USS LSM-167 off loading onto a pontoon causeway. Raymond Massel to the USS LSM / LSMR Association
    LSM-275 186k USS LSM-275 beached at Okinawa, April 1945. Note the dead Japanese suicide swimmer in the foreground on the small craft ramp. George Coughlin to the USS LSM / LSMR Association
    LSM-275 69k USS LSM-275 at anchor, date and location unknown. Note USS LSM-275 is painted Camouflage Measure 31, Design 10L. Richard Kruse in memory of his
    grandfather Robert Yates USS LSM-275
    LSM-275 56k USS LSM-275 moored in a nest with other LSMs, date and location unknown. USS LSM / LSMR Association
    LSM-275 62k USS LSM-275 underway, date and location unknown. Wilson Corrum to the USS LSM / LSMR Association
    LSM-275 74k USS LSM-275 underway, departing San Diego Bay, date unknown.
    A Ted Stone photo.    		 USS LSM / LSMR Association
    LCI(L)-275 94k An undated photo of the forward side of USS LSM-275's conning tower depicting the ships insignia. Photo courtesy of Denis Huff.
    Photo from "Landing Craft, Infantry And Fire Support" by Gordon L. Rottman     		Robert Hurst
    USS Portunus (ARC-1)
    LSM-275 108k Plan view amidships of Portunus (ARC-1) during conversion at Mare Island Naval Shipyard, 28 June 1952. Photo shows how the LSM's tank deck was converted to undersea cable wells and the increased size of the ship's bridge structure.
    US Naval Shipyard Mare Island photo # NY9-13506-6-52.    		 USS LSM / LSMR Association
    LSM-275 100k Plan view forward of Portunus (ARC-1) during conversion at Mare Island Naval Shipyard, 28 June 1952. Photo shows the LSMs forward tank deck reconfigured for storage of undersea cables and the new foc'sle.
    US Naval Shipyard Mare Island photo.    		 USS LSM / LSMR Association
    LSM-275 116k Plan view aft of Portunus (ARC-1) during conversion at Mare Island Naval Shipyard, 28 June 1952. Photo shows the LSMs aft tank deck reconfigured for storage of undersea cables.
    US Naval Shipyard Mare Island photo # NY9-13507-6-52, now in the collections of the NARA San Francisco, Mare Island Naval Shipyard Ship Files.    		 Tracy White
    LSM-275 231k USS Portunus (ARC-1) commissioning party, Left to Right: Capt. W. L. Turney (Shipyard Commander), Capt. Watson T. Singer (Shipyard Admin. Officer), Chaplain H. C. Embry, Capt. W. A. Lent (Commander Submarine Base) speaker, 2 July 1952, at US Naval Shipyard Mare Island, Vallejo, CA.
    Vallejo Naval & Historical Museum, File name: ARC 1 13591-7-52    		 Darryl Baker
    LSM-275 256k Stern view of USS Portunus (ARC-1) during commissioning ceremony, 2 July 1952, at US Naval Shipyard Mare Island, Vallejo, CA.
    Vallejo Naval & Historical Museum, File name: ARC 1 13590-7-52    		 Darryl Baker
    LSM-275 82k Commissioning of USS Portunus (ARC-1), 2 July 1952, at US Naval Shipyard Mare Island, Vallejo, CA.
    US Naval Shipyard Mare Island photo # NY9-13551-7-52 now in the collections of the NARA San Francisco, Mare Island Naval Shipyard Ship Files.    		 Tracy White
    LSM-275 1377k "Vallejo Times Herald" newspaper article of 3 July 1952, covering the commissioning of Portunus (ARC-1)
    Vallejo Naval & Historical Museum, File name: ARC 1 Info    		 Darryl Baker
    LSM-275 67k USS Portunus (ARC-1) underway in San Francisco Bay, 22 August 1952 after completion of her conversion from LSM-275 to ARC-1.
    US Naval Shipyard Mare Island photo # NY9-14128-8-52 now in the collections of the NARA San Francisco, Mare Island Naval Shipyard Ship Files.    		 Tracy White
    LSM-275 58k USS Portunus (ARC-1) underway in San Francisco Bay in 22 August 1952.
    US Naval Shipyard Mare Island photo    		 USS LSM / LSMR Association
    LSM-275 186k Stern view of USS Portunus (ARC-1) off Mare Island Naval Shipyard, Vallejo, CA., 22 August 1952.
    Vallejo Naval & Historical Museum photo # ARC 114131-8-52    		 Darryl Baker
    LSM-275 79k USS Portunus (ARC-1) underway in 1954, location unknown. USS LSM / LSMR Association
    NRP Medusa (A5214)
    LSM-275 57k Ex-USS Portunus (ARC-1) in Portuguese naval service as NRP Medusa (A5214) underway in 1960, location unknown.
    Office Portuguese navy photo from "Jane's Fighting Ships" 1961-62 edition.    		 Robert Hurst
    LSM-275
    101427520    		 50k NRP Medusa (A5214) line drawing Tommy Trampp
    LSM-275
    101427521    		 49k NRP Medusa (A5214) moored pierside probably at Arsenal do Alfeite, date unknown. Tommy Trampp
    USS LSM-275 / USS Portunus (ARC-1)
    Dictionary of American Naval Fighting Ships (DANFS)
    Commanding Officers
    01LT. McLeod, Danial D. USNR6 October 1944 - September 1945LSM-275
    02ENS. Daly Jr., Adrian L., USNRSeptember 1945 - May 1946LSM-275
    03LT. Bailey, Robert Earwook, USN (USNA 1944)May 1946 - 21 April 1947LSM-275
     Decommissioned21 April 1947 - 2 July 1952 
    04LT. Siebenthal, Stanley Arthur, USN2 July 1952 - ?ARC-1
    05LT. Fleiner, Fred J., USNRno datesARC-1
    06LT. Harper, Roger Wesley, USN1958 - 30 April 1959ARC-1
    Courtesy Wolfgang Hechler and Ron Reeves
    Crew Contact And Reunion Information
    U.S. Navy Memorial Foundation - Navy Log
    USS LSM-LSMR Association
    Additional Resources and Web Sites of Interest
    Robert Yates and the LSM-275
    Back To The Navsource Photo Archives Main Page Back To The Amphibious Ship Type Index Back To The Service Force Ship Type Index Back To The Landing Ship Medium (LSM) Photo Index Back To The Cable Repairing or Laying Ship Medium (ARC) Photo Index
    Comments, Suggestions, E-mail Webmaster.
    This page is created and maintained by Gary P. Priolo
    All pages copyright NavSource Naval History
    Last Updated 16 April 2021