High Quality Content by WIKIPEDIA articles! Design A-150, also known as the Super Yamato class, was a Japanese plan for a class of battleships. Begun in 1938–39, the design was mostly complete by 1941. However, so that a demand for other types of warships could be met, all work on Design A-150 was halted and no keels were laid. Authors William H. Garzke and Robert O. Dulin have argued that Design A-150 would have been the "most powerful battleships in history" because of the massive size of their main battery of six 510 mm (20 in) guns as well as numerous smaller caliber weapons.