USS Portunus (AGP-4) Class

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USS Antigone (AGP-16) circa late 1945 or early 1946.
Click on this photograph for links to larger images of this class.

Class:        PORTUNUS (AGP-4)
Design:        Navy LST
Displacement (tons):        2,028 light, 4,100 lim.
Dimensions (feet):        328.0' oa, 316.0' pp x 50.0' e x 11.2' lim.
Original Armament:        1-3"/50 2-40mmQ 8-20mm (1943-44: AGP 4-5, 10-11)
Later armaments:        2-40mmQ 8-20mm (1945: AGP 15); 2-40mmQ 8-20mmT (1945: AGP 14, 16-18)
Complement:        240 (1944)
Speed (kts.):        11.6
Propulsion (HP):        1,800
Machinery:        G.M. diesels, 2 screws

Construction:

AGP	Name	Reclas.	Builder	Keel	Launch	Commiss.
4	PORTUNUS	13 Jan 43	NYd Philadelphia	12 Nov 42	11 Feb 43	12 Jun 43
5	VARUNA	13 Jan 43	Dravo, Pittsburgh	23 Aug 42	9 Dec 42	31 Aug 43
10	ORESTES	3 Nov 43	Chicago Bridge, Seneca	8 Jul 43	16 Nov 43	25 Apr 44
11	SILENUS	18 Dec 43	Chicago Bridge, Seneca	28 Oct 43	20 Mar 44	9 Aug 44
14	ALECTO	14 Aug 44	Bethlehem Steel, Hingham	12 Dec 44	15 Jan 45	28 Jul 45
15	CALLISTO	14 Aug 44	Bethlehem Steel, Hingham	31 Oct 44	29 Nov 44	12 Jun 45
16	ANTIGONE	14 Aug 44	Chicago Bridge, Seneca	15 Aug 44	27 Oct 44	14 May 45
17	BRONTES	14 Aug 44	Chicago Bridge, Seneca	15 Nov 44	6 Feb 45	14 Aug 45
18	CHIRON	14 Aug 44	Chicago Bridge, Seneca	16 Dec 44	10 Mar 45	18 Sep 45
19	(Unnamed)	(no)	Chicago Bridge, Seneca	--	--	--

Disposition:

AGP	Name	Decomm.	Strike	Disposal	Fate	MA Sale
4	PORTUNUS	18 Apr 46	13 Nov 46	6 Feb 48	MC/D	6 Feb 48
5	VARUNA	1 Apr 46	1 May 46	31 Jul 47	MC/D	31 Jul 47
10	ORESTES	29 Apr 46	23 Apr 47	15 Mar 48	MC/D	15 Mar 48
11	SILENUS	14 Mar 46	17 Apr 46	25 Jul 47	MC/D	25 Jul 47
14	ALECTO	28 Jun 46	23 Apr 47	10 May 48	Trf.	--
15	CALLISTO	9 May 46	23 Apr 47	14 May 48	MC/D	14 May 48
16	ANTIGONE	27 May 46	10 Jun 47	6 Feb 48	MC/D	6 Feb 48
17	BRONTES	14 Mar 46	17 Apr 46	28 Mar 47	MC/D	28 Mar 47
18	CHIRON	20 Feb 46	28 Mar 46	19 May 47	MC/D	19 May 47
19	(Unnamed)	--	--	21 Jul 44	Canc.	--

Class Notes:
FY 1942 (AGP 5, 10), 1943 (AGP-4), 1944 (AGP 11, 14-19), all as LSTs. All were built under LST contracts and reclassified and fitted as AGPs before entering service.

The three converted yachts assigned in 1941 to act as MTB tenders (later classified AGP 1-3) were quickly determined to be inadequate due to size, speed, and armament. In May 1942 the MTB training center at Melville, Rhode Island, recommended providing one adequate tender for every two squadrons of MTBs--potentially a large requirement. Throughout 1942 the Navy looked for possible solutions--a 554-foot whale factory ship, the VESTFOLD, was even considered in September and October--and it eventually found an answer in the LST program. In mid-1942 the landing craft program temporarily lost some of its urgency as plans for a 1943 Cross-Channel operation were deferred, and in October 100 of the 490 LSTs then on order were cancelled. The Navy apparently found that a few of the remaining LSTs could be spared to fill other critical needs. On 3 Dec 42 CominCh directed the conversion of three LSTs to repair ships for landing craft, and on 18 Dec 42 he directed that three more be converted to Battle Damage Repair Ships and two to Motor Torpedo Boat Tenders. On 2 Jan 43 three new hull type designations were proposed for these ships, respectively ARL, ARB, and AGP. The types and hull number assignments--which also included the reclassification to AGP 1-3 from PG of the three converted yachts already supporting MTBs, making the converted LSTs AGP 4-5--were approved by SecNav on 13 Jan 43. On 25 Jan 43 the LSTs designated to become ARB 1-2 and AGP-1 were changed from LST 326-328 to LST 328-330 to minimize unnecessary work by the shipbuilder, and this date is carried in BuShips records as the reclassification date for all three ARBs and both AGPs.

On 11 Jun 43, as part of a major review of auxiliary ship requirements, the Auxiliary Vessels Board stated that, with the great numbers of ships of all types in the various and extended operating areas, it considered that additional repair ships were essential at the earliest practicable date, and that in planning an auxiliary vessel conversion program for 1944 and 1945 the conversion of LSTs and EC2 ships to repair ships was the most expeditious and economical method of meeting maintenance needs. It noted that these converted ships could relieve to a great extent the installation of shore-based repair facilities in the forward operating areas. As part of this effort, it recommended that a program of four LST conversions to AGPs be authorized, two in 1944 and two in 1945. These were AGP 10-11 and 14-15. The reclassification of AGP 10-11 from LSTs was approved on 3 Nov 43, although the LST designated in this action for AGP-11, LST-519, was changed to LST-604 on 18 Dec 43. On 22 Mar 44 CNO directed BuShips to nominate LST hulls for AGP 14-15; the hulls were reclassified in August with AGP 16-19.

On 2 May 44 the Auxiliary Vessels Board reviewed the construction program of ARBs and AGPs that it had authorized on 11 Jun 43 and concluded that the number of these ships provided for was inadequate. It recommended that four more AGPs of the LST type be constructed for delivery, one in each quarter of 1945. These ships were AGP 16-19. Of these, AGP-19 was quickly deleted from the program. The LST hulls for AGP 16-18 were reclassified on 14 Aug 44.

All units of this class were converted to AGP's by the Maryland DD Co., Baltimore, except AGP-5 (Tampa SB Co.). Units built on the Mississippi River were taken to New Orleans, where they remained for three days for voyage repairs and loading of stores. Combat crews then delivered them to Baltimore, with a three-day shakedown at St. Andrews Bay, Florida, to ensure their safe passage. Although these ships were officially reclassified on the dates shown here (which come from BuShips and OpNav records), they made the transit from the building to the conversion yards using their LST hull numbers and began using their AGP numbers only upon decommissioning and entering the conversion yard. (This date was reported as 8 May 43 for AGP-5 and 1 May 44 for AGP-11.)

Gibbs and Cox was the design agent for all three LST conversion designs. In the earlier AGPs the bow ramp and bow door control gear were not installed during construction and the bow doors were welded shut. In the ships that had a 3"/50 gun on the main deck aft the entire stern anchor-handling rig with its 3,000 pound Danforth anchor was moved to the starboard bow to provide emergency anchoring facilities, although the anchor appears to have been quickly moved to a new hawse pipe. This class was designed with shops and equipment for maintenance of one MTB squadron. They had greater lifting capabilities than other AGPs (except the two converted C1 cargo ships of the AGP-12 class, which had a 50-ton boom). The ships were initially designed with two ten-ton booms, but a 50-ton "A" frame hoist was soon added. This was a general purpose hoist, capable of supporting a motor torpedo boat in its cradle when in stripped condition. The full load displacement of the largest PT boat before stripping was 56 tons.

The design of the last five units of the class, AGP 14-18, was modified in a manner similar to the CORONIS (ARL-10) class, to include elimination of the 3"/50 DP gun and retention of the bow doors and operating mechanism. One purpose of these changes in the ARL-10 class was to provide facilities to embark and repair LVTs. Forward in the AGPs, the after kingpost and the front end of the deckhouse were moved forward, increasing the space available for repair shops, and the forward kingpost and boom were replaced by a crane. Aft, the 3"/50 gun was deleted and the 40mm quadruple mount was moved to a raised platform on the extreme stern, under which the usual LST stern anchor was restored. The lift capacity of the "A" frame hoist in the five new ships was increased to 60 tons, and in AGP-14 and AGP 17-18 a second "A" frame hoist was fitted to starboard.

Ship Notes:

AGP	Name	Notes
4	PORTUNUS	Ex LST-330 25 Jan 43, ex LST-328 13 Jan 43. Converted by Maryland DD, Baltimore, Md. (arrived from Philadelphia for conversion 25 Feb 43, no ferry commission being needed for this inland waterways transit). Sold by MC as LST-330 for scrap.
5	VARUNA	Ex LST-14 13 Jan 43. Ferry commission as LST-14 26 Mar-16 Apr 43. Converted by Tampa SB, Tampa, Fla. (contract signed 4 Feb 43). Sold by MC as LST-14 for mercantile service, became merc. GUARAUNA 1948.
10	ORESTES	Ex LST-135 3 Nov 43. Ferry commission as LST-135 30 Nov 43 to 13 Jan 44 (from reduced to full commission at New Orleans 14 Dec 43). Converted by Maryland DD, Baltimore. Designated 27 Jun 46 for lend lease to China, subsequently cancelled. Sold by MC as LST-135 for scrap.
11	SILENUS	Ex LST-604 18 Dec 43. Ferry commission as LST-604 3-29 Apr 44 (from reduced to full commission at New Orleans 8 Apr 44). Converted by Maryland DD, Baltimore (begun 1 May 44). Sold by MC as LST-604 for mercantile service, merc. ARZELL III (or II) 1948, became PAULA 1956.
14	ALECTO	Ex LST-977 14 Aug 44. Ferry commission as LST-977 8-23 Feb 45. Converted by Maryland DD, Baltimore. Trf. to Turkey through the Office of the Foreign Liquidation Commission (OFLC) on paper on 14 Feb 48, delivered on 10 May 48, renamed ONARAN. BU Sep 93.
15	CALLISTO	Ex LST-966 14 Aug 44. Ferry commission as LST-966 22 Dec 44-4 Jan 45. Converted by Maryland DD, Baltimore (begun 5 Jan 45). Approved 27 Jun 46 for lend lease to China, subsequently cancelled. Sold by MC as LST-966 for mercantile service, merc. ELENA 1949, lost as DAYTONA 20 Nov 55..
16	ANTIGONE	Ex LST-773 14 Aug 44. Ferry commission as LST-773 7 Nov-5 Dec 44. Converted by Maryland DD, Baltimore (begun 6 Dec 44). Sold by MC as LST-773 for scrap.
17	BRONTES	Ex LST-1125 14 Aug 44. Ferry commission as LST-1125 17 Feb-10 Mar 45. Converted by Maryland DD, Baltimore. Sold by MC as LST-1125 for mercantile service, merc. BARBARA 1947. Lost 27 Oct 59 as XALAPA.
18	CHIRON	Ex LST-1133 14 Aug 44. Ferry commission as LST-1133 23 Mar-17 Apr 45. Converted by Maryland DD, Baltimore. Sold by MC as LST-1133 for mercantile service, merc. ALTAMAR 1948, lost 27 Mar 60.
19	(Unnamed)	To have been ex LST-1152 but conversion cancelled 21 Jul 44.