The I-16, I-18, I-20, I-22, and I-24 were assigned to deliver midget submarines for the harbor attack. A fleet leaving on the morning of 6 December might pass before they were positioned. Even a submarine that sighted the sortie could prioritize concealment and its assigned harbor mission over an improvised attack while burdened with a parasite craft.
Notable Point · 1:13:55-1:15:15
Why the Japanese submarine screen might miss the departing fleet
Five Japanese submarines carrying midget craft were still moving into launch positions, making interception of a 6 December sortie unlikely.