SS Centaurus

''Portmar'' was a United States-flagged merchant vessel that was constructed in response to World War I, operated by a succession of companies in the interwar period, then taken up for wartime shipping in World War II.

The ship was built to Design 1013, as part of wartime orders by the United States Shipping Board (USSB). She was laid down by Northwest Steel of Portland, Oregon, with the name ''West Minsi''. The USSB order was cancelled during construction, but Northwest Steel completed the ship for private sale. She was sold to the Green Star Line before launching in November 1919, and was assigned the name ''Centaurus''. The freighter was sold to Nafra in 1920, then on to the Planet Steamship Company in 1923. In 1929, the ship was sold to the Calmar Steamship Company, who renamed the ship ''Portmar''.

In late 1941, ''Portmar'' was chartered by the United States Department of War to carry supplies to the Philippines but due to the Japanese invasion of the Philippines was retained in Australia. She was used in February 1942 to carry reinforcements from Darwin for the defenders of Timor prior to the Japanese invasion. The reinforcement convoy was shadowed by Japanese planes and attacked, forcing its cancellation. ''Portmar'' returned to Darwin on 18 February, and was still in harbour the next day when Japanese carrier-based aircraft attacked the city in the first ever attack on Australia. The ship was heavily damaged, and run aground to prevent sinking.

''Portmar'' was later refloated, towed to Sydney, repaired, purchased by the United States Army and put back into service as an Army transport. In June 1943, she sailed as part of convoy GP55. On 15 June, off Smoky Cape, ''Portmar'' and the landing ship were torpedoed by the Japanese submarine ''I-174''. Due to a highly volatile cargo, ''Portmar'' was abandoned and sank in less than ten minutes. She was the last ship lost to the Japanese submarine campaign in Australian waters.

Design and construction

The ship was built to Design 1013 or the "''Robert Dollar'' type", a standardised freighter design ordered by the United States Shipping Board (USSB) from multiple west-coast shipyards during World War I.McKeller, ''Steel Shipbuilding under the U. S. Shipping Board, 1917–1921: Contract Steel Ships, Part I'', p. 475a Standard dimensions were in length, with a beam of and a standard draft of . This vessel varied a little from the standard, being long and beam. Depth was with a draft of .

They had a deadweight tonnage value of 8,800, and a gross register tonnage of 5,551. Her net register tonnage was 3,418. Propulsion machinery varied across the type: this ship used oil-fuelled boilers, connected to triple-expansion steam engines. The engine was built by the Hooven, Owens & Rentschler Company of Hamilton, Ohio. It had cylinders of , and diameter by stroke. It was rated at 582 NHP. One hundred and five vessels were completed for the USSB, while this ship and four others were cancelled but completed and sold privately by the shipyards, and others cancelled outright.

The ship was laid down by Northwest Steel of Portland, Oregon as yard number 38 and USSB number 2373, with the name ''West Minsi''.McKeller, ''Steel Shipbuilding under the U. S. Shipping Board, 1917–1921: Contract Steel Ships, Part I'', pp. 477–8 During construction, the order for this ship was cancelled by the USSB Emergency Fleet Corporation, but construction continued for private sale.McKeller, ''Steel Shipbuilding under the U. S. Shipping Board, 1917–1921: Contract Steel Ships, Part I'', p. 478 By the time the ship was launched on 17 November 1919, she had been sold to the Green Star Line and assigned the name ''Centaurus''. The ship was completed in December 1919, and assigned the United States official number 219283 and Code Letters LTVH.

Operational history

The first voyage of ''Centaurus'' departed from Astoria, Oregon in late December 1919, bound for Callao, Peru. During the voyage, one of the crewmen suffered a mental breakdown over concerns about his invalid passport. Instead of providing medical assistance, the sailor was placed in irons, removed from the crew list and relisted as a stowaway, then abandoned on the dockside when ''Centaurus'' departed Callao on 17 January 1920. The crewman ended up in an insane asylum, where he died later that year.

* 18 January 1920. The newspaper "The Sunday Oregonian", Portland, wrote on the page 46:
GREEN STAR WILL PLY ATLANTIC

Four Steamers Purchased Here to Sail From Baltimore.

ORIENTAL RUN PROMISED

Cruft Now Being Built at Standifer Plant Expected to Be Operated on Pacific.

Speculation as to the future field of operations of the Green Star Steamship company, which purchased four steel steamers in Portland and placed orders for the construction of five more, was ended last week by a formal announcement from the headquarters of the company in Baltimore, where the Green Star line has pur chased a large building to serve as a home for its shipping enterprises. The last of the steamers purchased by, the line here, the ''Circlnus'', sailed from Astoria Wednesday with a full cargo of lumber for Melbourne and Adelaide, Australia. This cargo amounted to 4.086,103 feet, it is reported by Brown & McCabe, stevedores, who had charge of loading the vessel.

The three other steamers purchased here by the Green Star line are the ''Corvus'', which went in ballast to Arica, Chile, to load nitrates for Europe; the ''Centaurus'', which took a part cargo of lumber here and went to San Francisco to finish a general cargo for the west coast, and the ''Clauseus'', which went from here to San Francisco in ballast to load beans for Hamburg.> GREEN STAR WILL PLYS ATLANTIC"> The Sunday "OREGOXIAX, PORTLAND," JANUARY 18, 1920. >> GREEN STAR WILL PLYS ATLANTIC
/ref>

Later in 1920, ''Centaurus'' was sold to Nafra Company which was affiliated with Green Star having intertwined financial affairs in ship acquisition. She operated for this company until 1923, when she was sold to the Planet Steamship Company. In December 1929, ''Centaurus'' and four other Planet freighters (''Circinius'', ''Corvus'', ''Clauseus'', and ''Eurana'') were sold to the Calmar Steamship Company.

* 13 of December 1929. The newspaper "Oakland Tribune" in Oakland, California, wrote:

"CALMAR BUYS SHIPS.

The "Calmar Line" has purchased five freighters from the "Planet Steamship company", according to announcement from New York. This purchase increases the Calmar intercoastal fleet to eleven ships. The new craft are 880 tons register.

The vessels involved are all well known on this coast, consisting of the ''Circinius'', ''Corvus'', ''Clauseus'', ''Centaurus'' and ''Eurana''. They have run into local ports for several years under the Isthmian Line houseflag".

''Centaurus'' was renamed ''Portmar'', and her port of registry was changed to New York. In 1934, her Code Letters were changed to KOPZ. On 13 July 1937, while on a voyage from Boston, Massachusetts to Philadelphia, Pennsylvania, ''Portmar'' collided with the ''Handkerchief Lightvessel'' in dense fog. Although she was undamaged, the lightvessel was severely damaged.

World War II

On 18 November 1941, ''Portmar'' and seven other ships (, , , ', , , and ) were chartered by the United States Department of War to carry military supplies to the Philippines. The ship was effectively delivered to the United States government on 20 November 1941 in what was a precursor of the delivery of all ocean merchant shipping to the War Shipping Administration with allocation to the Army. Even though details of the charters were deemed confidential, the names of all eight ships were published in the ''Los Angeles Times'' two days later. The Japanese invasion of the Philippines resulted in retention in Australia. ''Portmar'' had arrived in Australia as one of the ships carrying fuel and vehicles after the earlier arrival of the diverted Pensacola convoy. ''Portmar'' had departed San Francisco 26 November 1941 sailing independently with 319 vehicles, 5,939 barrels of gasoline, ammunition, bombs, machine guns and other stores for the units sailing in the Pensacola convoy but was diverted while south of Hawaii, first to Suva then to Sydney with arrival there 31 December 1941.

The ship was one of those initially chosen to attempt to run the Japanese blockade of the Philippines but the rapid Japanese advance and occupation of Rabaul, Kavieng and other strategic points to the north resulted in the ship being recalled to Darwin. The Maritime Commission was expecting ''Portmar'' along with other large vessels to be returned to the United States but the desperate need for shipping in theater had made local retention necessary.

Before 02:00 on 15 February 1942, ''Portmar'' sailed from Darwin as part of a convoy carrying reinforcements for the defenders of Timor.Gill, ''Royal Australian Navy, 1939–1942'', pp. 581, 585 Also in the convoy were the transports , , and , with an escort made up of the cruiser , the destroyer , and the sloops and .Gill, ''Royal Australian Navy, 1939–1942'', p. 581 ''Portmar'', along with ''Tulagi'', carried elements of the U.S. Army 148th Field Artillery while the other ships had Australian forces embarked. By 11:00, the ships had been spotted by a Japanese flying boat, which followed them for several hours before dropping bombs at around 14:00 with minimal effect.Gill, ''Royal Australian Navy, 1939–1942'', p. 585 The next day, another flying boat began shadowing the convoy around 09:15, and the ships were attacked by a force of 45 Japanese aircraft two hours later. Light damage and some casualties were suffered aboard ''Manua Loa'', while ''Portmar'' was not damaged during the hour-long attack. The likelihood of further attacks and the believed imminent invasion of Timor resulted in orders to turn the convoy around received at 15:15, with all ships back at Darwin by midday on 18 February.

''Portmar'' was still in Darwin Harbour the next day when a force of Japanese carrier-based aircraft attacked the city: the first time Australia had been attacked. She was heavily damaged during the attack, and was towed away from her mooring and run aground to prevent her from sinking.Grose, ''An Awkward Truth'', p. 111 One of the crew was killed, and several wounded were later recovered by the examination vessel .Gill, ''Royal Australian Navy, 1939–1942'', p. 593

''Portmar'' was salvaged and reconditioned by U.S. Army port-battalion troops, towed to Sydney, and repaired.Gill, ''Royal Australian Navy, 1942–1945'', p. 261 The ship was purchased at Brisbane by the War Department on 17 November 1942 and incorporated into the U.S. Army's permanent local fleet as an Army transport.

On the morning of 15 June 1943, USAT ''Portmar'', loaded with ammunition and fuel, left Sydney for Brisbane as part of convoy GP55. The convoy consisted of ten merchant ships (including ''Portmar'') and three Landing Ship Tank vessels, escorted by the ''Bathurst''-class corvettes , , , , and . ''Portmar'' was the middle of three ships in the fourth column. ''Portmar'' had trouble maintaining position during the voyage, and at 17:15 on 16 June, when the convoy was east of Smoky Cape, was passing to port of USS ''LST-469'' to regain convoy position. At this time, the Japanese submarine ''I-174'' fired a spread of torpedoes at the convoy from the convoy's starboard: one torpedo struck USS ''LST-469'', and another hit ''Portmar'' almost immediately after. The volatile cargo was ignited, and the order was given to abandon ship. ''Portmar'' sank ten minutes later, with two crewmen killed. The 71 survivors were recovered by HMAS ''Deloraine'', which then took USS ''LST-469'' (which had survived the attack, but was immobilised and had suffered heavy casualties) in tow, and headed for Coffs Harbour. ''Warnambool'' and ''Kalgoorlie'' depth-charged the area until contact was lost: they were unable to damage ''I-174'', nor were subsequent searches able to locate her. The attack on convoy GP55 was the last Japanese submarine attack in Australian waters.Gill, ''Royal Australian Navy, 1942–1945'', p. 262 The loss of shipping, particularly the LST that was part of MacArthur's Seventh Amphibious Force, forced removal of troops and supplies for the occupation of Kiriwina and Woodlark Island, the first offensive amphibious operations.

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{{DEFAULTSORT:Portmar
1919 ships
Design 1013 ships
Maritime incidents in February 1942
Maritime incidents in June 1943
Merchant ships of the United States
Ships built in Portland, Oregon
Ships sunk by Japanese submarines
Shipwrecks of the Mid North Coast Region
Steamships of the United States
Transport ships of the United States Army
World War II merchant ships of the United States
World War II shipwrecks in the Pacific Ocean