The Navy over the next few years aims to shorten deployments for sailors aboard aircraft carriers and other ships to eight months, a Navy admiral said.

The Navy plans to start the Harry S. Truman Carrier Strike Group’s three-year deployment readiness cycle in November for an eight month deployment to begin on an undisclosed date, according to Adm. William E. Gortney, commander of Fleet Forces Command.

The new standard cruise length -- down from as many as 10 months today but up from six months decades ago -- will be gradually introduced to other strike groups over the next three to four years, Gortney said Thursday during a phone conference with reporters. It's part of an updated readiness effort, known as the Optimized Fleet Response Plan, designed to give sailors more time with their families while improving ship maintenance schedules, he said.

"We can't flick a switch and we're all on eight-month deployments and manning's perfect," the admiral said. "This is a pretty significant change. We have to phase ourselves in."

The Navy for years has been operating at a higher-than-normal tempo in support of the U.S.-led wars in Iraq and Afghanistan, as well as international missions such as conducting airstrikes against Libya, providing humanitarian relief after the nuclear disaster in Japan, and monitoring the civil war in Syria.

Gortney was clear that eight-month cruises are not guaranteed and could be lengthened if a national-security need arises.

"The world gets a vote," he said.

But the service wanted to make an effort to give sailors more time at home, Gortney said. Nine- to 10-month deployments are "just not sustainable over the long haul" because of the stress it creates for servicemembers, he said. Even eight months at sea puts them close to the "ragged edge," he said.

While cruises are scheduled to decrease to eight months, the overall maintenance, training and deployment cycle will increase to 36 months under the plan, Gortney said. The result is that sailors can expect to spend almost 70 percent of the three-year period stateside -- up from about 50 percent now, he said.

"It's not just deployment length," he said. "It's total time away from home that matters."

The Navy decided to begin applying the new schedule to carrier strike groups because they account for as much as 85 percent of the naval fleet, Gortney said. A typical strike group includes an aircraft carrier and associated air wing of about 70 aircraft, a cruiser and two destroyers or frigates.

Gortney didn't specify which strike groups will follow the Truman and when. But he said it may take about four years to fully transition all carriers, cruisers and destroyers to the new schedule. Amphibious assault ships and submarines would follow thereafter, he said.

Update: An earlier version of this report incorrectly stated that the Truman’s eight month deployment would start in November. The deployment readiness cycle will start in November, not the actual deployment.