Over the past 100 years, American (or any country’s) aircraft carriers have been slowly getting longer with the majority of them ranging anywhere between 800 to 1100 feet (244 to 336 meters) in length. That said, USS Enterprise which was the longest aircraft carrier in the world (with a length of 1122 feet/342 meters) was still about 25% shorter than the largest ship ever built, the Supertanker Seawise Giant.
There are even cruise ships longer than USS Enterprise, moreover the newest American aircraft carrier USS Gerald R. Ford is actually 17 feet shorter than USS Enterprise. So the question is why are aircraft carriers are not built to be longer? After all, a larger carrier would be able to handle more aircraft, and isn’t that a good thing?
Here are four primary reasons Why aircraft carriers are not built to be any longer:
Number 4- Cost
Obviously, larger aircraft carriers would be more costly to build and maintained. The U.S. Navy budget for fiscal 2020 was over 160 billion dollars, which is a lot of money but it’s not unlimited. Given a fixed budget, building larger carriers means having smaller fleet, which goes against the U.S. Navy’s current plan to increase its fleet size to 355 ships.
Number 3- Maneuverability
Aircraft carriers need to be agile and have the ability to change their course as quickly as possible. The bigger vessel will have a bigger turning circle, which may be okay for an oil tanker, container or any other type of cargo ship but it will be a negative point for an aircraft carrier, specially if they ever come under attack. Also, while docking, good manuevrability at slow speed is a plus point for the aircraft carriers. If you’ve experience of handling big vessels, you will easily relate to this.
Number 2- Docking
Commercial vessels like cruise ships go through pre-determined routes, and as part of their itinerary visit specific ports around the world. Those ports are specifically chosen as they can accommodate these larger vessels, but aircraft carriers need to be flexible about places where they can be docked and repaired. The large dry docks that are needed to repair these vessels are limited around the world and the larger the vessel, the less options will be available.
Number 1- Speed
Cargo ships can travel at 15-25 knots, and cruise ships travel at an average speed of about 20 knots but aircraft carriers will not really be functional at such speeds. The primary function of the carriers is facilitating launching and landing of aircraft, and in order to safely take off aircraft need a certain amount of speed which will generate enough lift force to enable the aircraft to fly.
On an aircraft carrier there are two main components contributing to the lift force, one is the aircraft catapult speed, and the other is the apparent wind on the flight deck. The catapult can accelerate the aircraft from 0 to 150 knots in about 2 seconds, during which the pilot experiences over three times the force of gravity. In addition to this the aircraft’s jet engines also contribute to the acceleration needed for take off but it is not enough. An addition of 30-40 knots of speed is still required and this is exactly where the carriers’ speed becomes of utmost importance. When aircraft are launching, the carrier is always moving into the wind, so the apparent wind speed is equal to the true wind speed at the ocean plus the speed of the carrier itself, and this is precisely why most of the aircraft carriers must be able to produce a maximum speed of over 30 knots.
In summary, aircraft carriers need a minimum amount of speed and maneuverability, the ability to be accommodated in a wide variety of ports and pass through waterways like the Suez and Panama Canal. Any increase in their size may negatively impact these characteristics.
Here is an interesting video by Not What You Think explaining in detail Why the aircraft carriers are smaller than cargo ships: