Mediterranean experience and assumptions about submarine targets

Exercise allowances drew on the number of charges needed against First World War submarines. Those boats generally dived less deeply, were smaller and differed in construction from later targets. Much Japanese anti-submarine experience during World War I had come from the Mediterranean, where clear water could reveal shallow-diving submarines. Applying that experience to a different region and different boats could help explain inadequate ammunition estimates. British and French estimates receive similar criticism, while Italy continued to operate in waters closer to its earlier experience. An alternative explanation is institutional: questioning existing assumptions would expose problems for which spare budget and industrial capacity were unavailable.