SCB-125やSCB-125Aを受けたエセックス級航空母艦や、SCB-110以降のミッドウェイ級航空母艦のことだと思います。前者は８缶、後者は12缶のボイラーを搭載しておりましたので、若干の最高速度は低下しても、スチーム・カタパルトの運用には、ほとんど影響はなかったようです。

また、現在の空母では、最速４器のカタパルトで20秒に1機を発艦することができます：
Aircraft Carriers
http://fas.org/man/dod-101/sys/ship/cv.htm

しかし、これはカタパルトの発艦能力によるのではなく、あくまでも、航空機の飛行条件によってきまるのです。


Departure/recovery types

There are three types of departure and recovery operations, which are referred to as case I, case II, and case III. Primary responsibility for adherence to the departure rests with the pilot; however, advisory control is given by the ship's Departure Control radar operators, including when dictated by weather conditions.

Case I
When it is anticipated that flights will not encounter instrument conditions (instrument meteorological conditions) during daytime departures/recoveries, and the ceiling and visibility around the carrier are no lower than 3,000 feet (910 m) and 5 nautical miles (9.3 km; 5.8 mi) respectively.
Immediately after becoming airborne, aircraft raise their landing gear and perform "clearing turns" to the right off the bow and to the left off the waist catapults. This ~10° check turn is to increase separation of (near) simultaneously launched aircraft from the waist/bow catapults. After the clearing turn, aircraft proceed straight ahead paralleling the ship's course at 500 feet (150 m) until 7 nautical miles (13 km; 8.1 mi). Aircraft are then cleared to climb unrestricted in visual conditions.

Case II
When it is anticipated that flights may encounter instrument conditions during a daytime departure/recovery, and the ceiling and visibility in the carrier control zone are no lower than 1,000 feet (300 m) and 5 nautical miles (9.3 km; 5.8 mi) respectively. Used for an overcast condition.
After a clearing turn, aircraft proceed straight ahead at 500 feet paralleling ship's course. At 7 nautical miles (13 km; 8.1 mi), aircraft turn to intercept a 10-nmi arc about the ship, maintaining visual conditions until established outbound on their assigned departure radial, at which time they are free to climb through the weather. The 500-foot (150 m) restriction is lifted after 7 nautical miles (13 km; 8.1 mi) if the climb can be continued in visual conditions.

Case III
When it is anticipated that flights will encounter instrument conditions during a departure/recovery because the ceiling or visibility around the carrier are lower than 1,000 feet (300 m) and 5 nautical miles (9.3 km; 5.8 mi) respectively; or for night time departures/recoveries.
A minimum launch interval of 30 seconds is used between aircraft, which climb straight ahead. At 7 nautical miles (13 km; 8.1 mi), they turn to fly the 10-nmi arc until intercepting their assigned departure radial.
佐久間多聞

回答ありがとうございます

たしかにカタパルトの使用や艦の速度に支障があれば複数の艦に装備しませんね、納得しました。


あああ