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USS Portunus (ARC 1) on 22 August 1952.
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Design: Navy LSM 1
Displacement (tons): 700 light, 1,220 full
Dimensions (feet): 204' oa, 197' wl x 35' e, 34' wl x 11' max nav
Armament: 2-20mmS
Accommodations: 9 officers, 60 enlisted
Speed (kts.): 13
Propulsion (HP): 3,600
Machinery: Diesel (direct), 2 screws

1PORTUNUS4 Dec 1950Federal, Newark1 Aug 194411 Sep 19442 Jul 1952

ARCNameTDecommStrikeDisposalFateMA Sale
1PORTUNUS30 Apr 19591 May 19591 Nov 1959Trf--

Class Notes:
On 31 May 1950 the Ship Characteristics Board promulgated the first preliminary characteristics for an LSM conversion for the SOFAR project, Shipbuilding Project No. 55. According to these preliminary characteristics the ship's mission was to support facilities utilizing submarine cable, including SOFAR and harbor defense installations. Her primary task was to install, repair, and replace ocean bottom hydrophones and associated cable at depths up to about 600 fathoms, and her secondary task was to install, repair, and replace underwater cables and hydrophones associated with harbor defense equipment and other special underwater devices. Her existing Fairbanks-Morse diesel engines were to be fitted with a modified hydraulic coupling or other device permitting continuous operation at all speeds from 1 knot to maximum sustained speed. The interior was also to be decked over, the bow welded shut, and the pilot house placed on the centerline. Cable handling machinery and cable tanks would have to be installed. She was to have two 20mm single mounts for mine disposal purposes. On 4 December 1950 the Navy established the new classification ARC for cable repairing or laying ship. At the same time, in view of the selection of LSM 275 for conversion to a cable repairing or laying ship, her designation was changed to ARC 1. She was commissioned at Mare Island on 2 Jul 1952 and the name PORTUNUS was approved for this her on 13 July 1953. She was replaced by YAMACRAW (ARC 5) in 1959.

Ship Notes:
1PORTUNUSFY 1951. (ex-LSM 275, compl. 5 Oct 1944). Trf. Portugal 1959 as MEDUSA, renamed SAN RAFAEL 1974.

Page Notes:
Compiled: 19 Oct 2021
© Stephen S. Roberts, 2021
Sources: DB, Maroon