The Number 13 proposal combined eight 18-inch guns and 30 knots on a projected normal displacement of 47,500 tons. Its protection included a 13-inch belt and a 5-inch deck, both treated as substantial for the early 1920s. The secondary armament comprised sixteen 5.5-inch guns, eight 4.7-inch anti-aircraft guns and eight 24-inch torpedo tubes. The planned speed was three knots higher than Yamato's, offering a heavily armed anchor for the Eight-Eight fleet. In Alex Clarke's assessment, this was the Japanese design most likely to force the Royal Navy to develop a specific response instead of continuing its existing programme.
Chapter · 1:54:32-1:57:14
The Number 13 class could have forced a British answer
Eight 18-inch guns, 30 knots and substantial protection on 47,500 tons made Number 13 the Japanese design singled out as a potential trigger for a British response.