Some Japanese sources, and the Wikipedia entry, list a fourth group consisting of one vessel, Kyuei Maru. However, information on her is scarce, spotty, and decidedly uncertain. It seems more likely that she was a member of the following 1TL type, and not an original Kawasaki type.
A more legitimate fourth group of three ships was built by the Harima Shipyards (which is not too far from the Kawaski, Kobe shipyards) to the Kawasaki design. These were Akatsuki, Akebono, and Kuroshio Maru. Completed 1937 – 1939, they were dimensionally the same as the original design, but differed in small details. The bridges, particularly the concavity of the facings, were closer in shape to the original Toa and Kyokuto Maru. However, the bridges were situated in the revised location shared by the second and third Kawasaki groups. The wings of the second level were also plated in as with the later Kawasakis. The Harima built ships also had apertures in the bridge face, to either side of the central trunk, similar to those on Kenyo, Kokuyo and Nippon Maru. However, these apertures were completely open, with no support columns. The openings were also a little narrower.
Other visual differences are seen mostly in the hull plating cutouts that mark the transition from the main deck to the 01 deck, and again to the boat deck. In the Kawasaki type, these are straight edged slants, whereas the Harima built ships have concave transitions. The only exception is where the bridge meets the main deck; there are no transition plates at all, fore and aft, for the Harima built ships.
One last visual references has to do with the set of joined kingposts aft the bridge. They were of a slightly simpler design than those of the original Kawasakis.
Kurushio Maru differed from her sisters in having steam boilers instead of diesels. Accordingly, her intake set-up atop the rear superstructure was somewhat simplified and reduced. Ultimately, this design variation was chosen as the plan for the subsequent wartime standard 1TL tanker design. (I may expand this CASF in the future to include this class.)
Photo credits: Akitsuki Maru – Ships of the World vol. # 826, Wikipedia, Acme News Pictures,Los Angeles bureau; Akebono Mau- ONI, unknown via Motoyuki Iwashige; Kuroshio Maru – SOTW vol. # 826)
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Akitsuki Maru prewar, SOTW v 826, 12-2015.jpg [ 162.13 KiB | Viewed 4522 times ]
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Akatsuki Maru prewar 2.jpg [ 82.79 KiB | Viewed 4522 times ]
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Akatsuki, January 27, 1940 at San Pedro #1.jpg [ 161.34 KiB | Viewed 4522 times ]
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Akatsuki, January 27, 1940 at San Pedro #2.jpg [ 197.6 KiB | Viewed 4522 times ]
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Akebono Maru, pre-war, ONI.jpg [ 69.56 KiB | Viewed 4522 times ]
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Akebono Maru, wreck.jpg [ 99.78 KiB | Viewed 4522 times ]
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Kuroshio Maru pre-war, SOTW v 826, 12-2015.jpg [ 187.63 KiB | Viewed 4522 times ]
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