The B class was a ship class of sixteen motor launches built in the Dutch East Indies for the Royal Netherlands Navy.Lenton (1968), p. 95.Gardiner and Chesneau (1980), p. 396. However, before the motor launches could be completed the Dutch East Indies was invaded by the Japanese.von Münching (1978), p. 116. To prevent the vessels from being captured they were scuttled.Mark (1997), p. 137. Nonetheless, seven motor launches were salvaged and completed as auxiliary submarine chasers by the Japanese and taken into service of the Imperial Japanese Navy as the Cha 103 class.Gardiner and Chesneau (1980), p. 396.

Design and construction The B-class motor launches were built in the Dutch East Indies at the shipyards of Droogdok Maatschappij Soerabaja, Marine Etablissement te Soerabaja and Indische Maatschappij Palembang. They were designed to be able to perform various roles such as auxiliary submarine chaser, patrol vessel and auxiliary minesweeper.von Münching (1978), p. 8. The launches measured in length, had a beam of and a draft of . Furthermore, they had a displacement of 130 tons and were equipped with diesel engines that could produce .von Münching (1978), p. 115. This allowed the launches to reach a maximum speed of . As armament they had a single naval gun, a single anti-aircraft gun, two machine guns and 20 depth charges.

Cha 103 class The seven motor launches that were salvaged and completed as auxiliary submarine chasers by the Japanese became known as the Cha 103 class. These submarine chasers were equipped with different diesel engines and armament in comparison to their original B class design.Lenton (1968), p. 96. Four chasers (Cha 103, Cha 105, Cha 107 and Cha 108) were equipped with diesel engines that could produce , which allowed them to reach a maximum speed of . Two (Cha 114 and Cha 115) were equipped with diesel engines that could produce , which allowed them to reach a maximum speed of 19 knots. While the last one, Cha 106, was equipped with diesel engines that could produce , which allowed the chaser to reach a maximum speed of . All auxiliary submarine chasers of the Cha 103 class were armed with a single Yamanouchi gun, a machine gun, a machine gun and two depth charge rails that could carry a total of 32 depth charges.

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