Aircraft carriers are the undisputed giants of today’s naval fleets, representing the pinnacle of maritime power projection. These formidable vessels serve as symbols of a nation’s military might, and while they are highly coveted, they come with a hefty price tag, making them a “crown jewel” affordable to only a select few major powers.

So, just how long does it take for a modern aircraft carrier to get underway? The answer: at least 10 hours!

Modern aircraft carriers are generally categorized by their power plant, namely, nuclear-powered aircraft carriers and conventionally powered aircraft carriers. However, when classified based on their propulsion systems, they fall into two main categories: steam turbines and gas turbines. Among these, countries like the United States, India (INS Vikramaditya), China, Russia, France, and others utilize steam turbines, also known as “boiling water” reactors. In contrast, China, India (INS Vikrant), Italy, and Japan’s light aircraft carriers predominantly rely on gas turbines for power.

The characteristic of steam turbines lies in their requirement for a large amount of high-temperature, high-pressure steam, which is then used to drive the steam turbine itself and propel the ship. Therefore, for aircraft carriers equipped with steam turbines, starting the engines involves a crucial step called “boiling water.” Taking China’s Liaoning aircraft carrier, for instance, it is fitted with four Type 12 boilers, requiring approximately 60 tons of boiler water to be heated before the ship can set sail. Notably, these steam turbines use “superheated steam,” which means the temperature exceeds 100°C and the pressure surpasses standard atmospheric pressure, creating high-temperature, high-pressure steam. According to reports, the steam temperature in the Liaoning’s steam turbine can reach up to 400°C. As a result, it takes around 10 hours to boil the 60 tons of boiler water into high-temperature steam at 400°C.

In terms of boiling water, nuclear-powered aircraft carriers have certain advantages over conventionally powered carriers. Even when nuclear-powered carriers return to port and dock, their nuclear reactors don’t completely shut down but rather maintain a low-speed operating state. Consequently, the time required to boil water before departure is much shorter than that of fuel-fired boilers, which can be found on conventionally powered carriers. According to the U.S. Navy, the Nimitz-class nuclear-powered aircraft carriers, for example, need only about 4 hours to boil water before setting sail, which is significantly faster than conventionally powered carriers.

As for gas turbines, their startup is notably quicker. Since the ship’s gas turbine is an adapted version of the aircraft engine, it simply requires air intake, ignition, and the generation of hot air through fuel combustion to drive the gas turbine and initiate propulsion. This eliminates the need for the intermediary step of boiling water. However, gas turbines come with their own set of challenges, such as their high fuel requirements, the necessity for purified distillate fuel, and the complexity of maintenance. Consequently, in terms of ease of use and versatility, steam turbines still hold an advantage.

Some may worry about the 10-hour water boiling process for steam turbine-powered carriers, especially in emergency situations. However, it’s important to note that military ports hosting aircraft carriers are heavily fortified and protected, making it challenging for hostile forces to effectively breach their defenses. Additionally, with multiple aircraft carriers in the fleets of major powers, carriers can be rotated and deployed as needed, ensuring a continuous naval presence at sea. So, while a 10-hour startup time may seem significant, it is not a major concern in practice.

In conclusion, aircraft carriers are the backbone of modern naval power projection, and their unique propulsion systems come with their own set of advantages and challenges. While the process of boiling water for steam turbines takes time, it does not pose a significant operational hindrance, thanks to the strategic planning and robust defenses of military ports hosting these vessels.