How Long Can A Military Submarine Stay At Sea Before Needing To Refuel And Replenish?
Nuclear reactors are amazing pieces of technology. They're clean sources of energy, generate tons of power around the world, and keep American aircraft carriers and submarines at sea. U.S. subs' nuclear power plants are among the components that make them such marvelous machines. Sure, there's the ability of military submarines to essentially stay underwater indefinitely, use sound to navigate the world's oceans, dive to depths that would crush most anything else manmade, and launch cruise missiles while submerged. But it's the nuclear reactor that lets these impressive metal tubes stay at sea between 15 and 20 years before they need to return to port to refuel.
The submarines in the U.S. Navy's bigger-than-you-think submarine fleet are built to be in service for nearly half a century. The Los Angeles-class fast attack submarines are being replaced with newer Virginia-class boats, but they've been in service since 1976, meaning they've only needed to refuel two or three times throughout their entire lifespan. Ohio-class ballistic-missile submarines were designed to remain in service for 30 years, but upgrades extended their operational lives to 42 years. The newer Columbia class is expected to have a service life of 42 years, too.
Refueling ballistic-missile and attack submarines is nothing like pulling your car into a gas station. It's a major event. They undergo what's known as an engineered refueling overhaul, which entails maintenance and alterations to a sub's interior, as well as replacing the nuclear reactor's fuel.
But nuclear subs do replenish their stores often
While many military submarines are nearly self-sustaining — their nuclear reactors generate power for more than a decade, and they can make fresh water, produce oxygen and remove excess carbon dioxide – they still need to return to port much sooner than the 15- or 20-year mark. A couple of factors prevent sailors from staying out that long, with the lack of fresh produce and other food being one. There are also health concerns when you're cooped up in an enclosed tube for too long. That's why ballistic-missile submarines have a specific routine for their patrols.
In the U.S. Navy, two crews (Blue and Gold) split the time on the sub. Patrols last an average of 77 days, and when they return to port the boat is worked on for an average of five weeks. Any damage it sustained on patrol is repaired in this time while it's also loaded up with a new stock of food and supplies.
However, there are instances where submarines are unable to return to port as scheduled. World navies have had subs remain on patrol for as long as 201 days, and a delay at sea requires something called a vertical replenishment. This involves a submarine surfacing while the U.S. Marine Corps or Air Force flies an aircraft overhead, delivering vital resources such as food or operational gear, and even swapping out its crew.