[2] Propulsion machinery varied across the type: this ship used oil-fuelled boilers, connected to triple-expansion steam engines.

[7] 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.

[9] 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.

[9] Later in 1920, Centaurus was sold to Nafra Company which was affiliated with Green Star having intertwined financial affairs in ship acquisition.

[7] In December 1929, Centaurus and four other Planet freighters (Circinius, Corvus, Clauseus, and Eurana) were sold to the Calmar Steamship Company.

[15] On 13 July 1937, while on a voyage from Boston, Massachusetts to Philadelphia, Pennsylvania, Portmar collided with the Handkerchief Lightvessel in dense fog.

[16] On 18 November 1941, Portmar and seven other ships (Iowan, Mauna Loa, West Camargo, Steel Voyager, Jane Christenson, F. J. Luckenbach, and Malama) were chartered by the United States Department of War to carry military supplies to the Philippines.

[19] 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.

[22] 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.

[3] Portmar, along with Tulagi, carried elements of the U.S. Army 148th Field Artillery while the other ships had Australian forces embarked.

[21][25] 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.

[26] 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.

[26] 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.

[19][23] On the morning of 15 June 1943, USAT Portmar, loaded with ammunition and fuel, left Sydney for Brisbane as part of convoy GP55.

[30] 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.