 The design of the Ibuki class was a minor improvement over the last pair of the Mogami class after those ships had been upgraded during the late 1930s . The main improvement was the replacement of the triple torpedo tube mounts in the older ships with quadruple mounts . They cost 60 @,@ 000 @,@ 000 yen each and had a crew of 54 officers and 822 enlisted men . 
