The US Navy sent two aircraft carriers to San Diego for a complicated switchover in which the crews of the two nautical giants change ships.

About 3,000 troops were affected by the move, which started August 10, with the bulk of the crews from the USS George Washington and the USS Ronald Reagan switching ships.

In naval parlance, such a change of personnel is called a "hull swap." The process was set to last 10 days.

The USS Ronald Reagan will relieve the USS George Washington as the Navy's only forward-deployed aircraft carrier in Yokosuka, Japan, the Navy said.

The George Washington will go to Newport News, Virginia, for a mid-life refueling complex overhaul, following a deployment around South America.

Each aircraft carrier has a crew of about 3,500 sailors and civilians. Some 1,500 personnel from each vessel was involved in the operation.

It was the first changeover of its scale since 2008, in an operation involving the USS George Washington and the USS Kitty Hawk.

"So far the swap has been a little stressful but it hasn't been too bad," said Ronika Peeples, who was being moved from the Washington to the Reagan.

"I'm actually happy to be back on the Ronald Reagan, I love the ship, it's so clean, it's so neat, everything is well put together."

Another aircraft carrier, the USS Theodore Roosevelt, will return to San Diego, its new home port, in the fall.