Hello Axel,
Welcome back. When I saw you again, I decided, that it is time for me, too. So, I start now...:-) Hello Siri, hello Friends!
I send you translation from "Senji Yuso Sendan Shi" (Wartime Transportation Convoys History) by Shinshichiro Komamiya.
I have translated information about all Japanese convoys from 11 December 1941 to 15 August 1945 (452 pages of brilliant information!). Is somebody is interested in, please, contact me directly.
And here is part interesting for Axel:
25th. November, 1943, at 1100.
From: Palau.
3rd. December, 1943.
To: Rabaul, New Britain.
Hokko Maru, Uchide Maru, Yuri Maru, Colombia Maru, Clyde Maru (5).
Submarine-chasers No. 24, No. 39 (2).
At 1010 on the 28th. at position 01.45N 141.52E, 500 kilometers north of Aitape, New Guinea, Yuri Maru was hit by three torpedoes on the port side all in No. 3 hold. These blew the ship in two and she immediately sank.
At the time Yuri Maru was carrying the 2nd. Landing Unit of whom thirty-eight died along with fourteen crewmen.
At the same time Hokko Maru was torpedoed at the stern, there was no chance of controlling the flood waters and she sank at 1114. At the time she was carrying 640 men of an army unit, one died along with three crewmen.
Meanwhile at 1011 Colombia Maru had discovered torpedo tracks heading for her, these she avoided. She then dropped depth-charges and opened-up with gunfire.
The culprit was the U.S.S. Raton, this submarine fired three torpedoes each at two ships for respectively three and two claimed hits and two sinkings. Raton reported nineteen depth-charges dropped.
After completing rescue work the convoy resumed it's eastward advance, at 2210 that evening the ships were attacked again but all torpedoes were evaded. In fact it was Ration again, the submarine fired four torpedoes each at two targets but claimed no hits.
The next day, the 29th. at 1510 a third submarine attack occurred, all torpedoes were avoided. Possibly this submarine was the U.S.S Gato, she fired three torpedoes at one ship for no results at position 02.43N 144.17E, in reply the submarine counted twenty-five depth-charges dropped.
At about 2000 an enemy submarine was discovered on the surface off the port side (Gato!), the convoy immediately began evasive maneuvers, meanwhile Submarine-chaser No. 39 opened fire and dropped depth-charges.
At this time there was a mild north wind blowing, strength 1, the weather was fine with good visibility which helped the lookouts.
The convoy continued onward, then at 1625 on the 30th. at position 01.56N 147.21E, 430 kilometers north of Manus Island Colombia Maru was stopped by torpedo hits in No. 1 and No. 4 (one report says No. 6) holds on the port side. She became powerless and flooding was fierce through the two holes. Because of this she was abandoned, she the drifted away and sank at about 2300. Colombia Maru was the victim of the U.S.S. Gato, the submarine fired four torpedoes for two claimed hits and a sinking, six depth-charge explosions were heard.
At Palau the ship had taken onboard 150 men of an army unit, 5800 tons of provisions, light fuel-oil and motor-boats. At the time of the disaster she also had aboard 180 survivors from the Yuri Maru. Counting her crew, passengers and rescued men only one man lost his life. Colombia Maru's cargo consisted of 4900 tons of provisions, 908 tons of sugar and 1000 drums of light fuel oil.
Yuri Maru was of 6787 tons, her owners were the Osaka Shosen Company.
Hokko Maru was of 5346 tons, her owners were the Yamashita Kisen Company.
Colombia Maru was of 5617 tons, her owners were the Mitsubishi Kisen Company.
Because of the above disasters all surviving ships were crowded with survivors, the Buenos Aires Maru later rescued men found drifting in three lifeboats and brought them to Rabaul.

Greetings,
Wawrzyniec