Why Kaga's battleship hull weakens Japanese carrier doctrine

The comparison gives Akagi a speed of 31.5 knots and Kaga 28 knots after the latter's 1935 modernization. Those extra 3.5 knots affect battle manoeuvres and wind over the flight deck. The quoted endurance figures also distinguish 10,000 nautical miles at 16 knots from the same distance at 15 knots. That one-knot difference is estimated to save roughly a day and a half to two days on a long passage. Japanese attrition doctrine makes distant operations important because they are intended to weaken the enemy before the decisive battle. Carrier mobility therefore matters both in launching aircraft and in reaching the earlier operations on which the final battle depends.