The U.S. Navy is reducing the number of days ships are at sea by a third, in order to reduce the wear and tear on its ships, and to provide cash and port time for needed maintenance. The problems began with the end of the Cold War in 1991, as the navy has sought to maintain the same high tempo of operations, and even increase it. That meant sending carrier and amphibious task forces out to sea for six month cruises to distant parts of the planet more frequently than before. After September 11, 2001, the tempo of operations increased even more, to support the war on terror.
To support all this on smaller post-Cold War budgets, the navy downsized. In the 1990s, the US Navy decommissioned over 300 ships. In 1990, the navy was still trying to increase warship strength of 600. With the end of the Cold War, and the threat of the huge (but now disintegrating) Soviet fleet, there were suddenly more crises and hot spots the navy felt it had to deal. So while only about a quarter of all ships were at sea during the Cold War, in the 1990s about a third were out there. This put more strain on sailors, as marriages fell apart and sailors got tired of the constant stress of sea duty.
In response, the navy has focused on building new ships that used 50-80 percent fewer sailors. This is not as extreme as it sounds, for commercial ships have been doing this for several decades. But the smaller crews have not arrived yet, because the new ships have proved too expensive to build. Meanwhile, the navy has been putting off doing a lot of ship maintenance, especially stuff that requires replacing lots of parts (like on engines and other mechanical and electrical gear). The result has been more ships failing inspections and having problems while at sea. So the decision to cut days at sea, and catch up on maintenance, makes sense.
In the last two years, the navy has switched from the "six month cruise" concept it used for most of the Cold War, and after, to the "surge" system. This means most ships spend most of their time at their home ports. The ships still go to sea for training, but this lasts a few days, or a week or so. Less time away from the family, and more time to do maintenance in port. And less wear and tear on the ships. Being at sea, even calm seas, wears the ships out.
The navy is also recognizing that, as the largest fleet on the planet (larger than all the others combined, at least in terms of combat power, if not numbers), the navy doesnt have to be out there as much. The world knows what the USN can do, and won't forget because a carrier task force doesn't come by for a year or so. The navy is also taking advantage of the smart bomb revolution. The GPS guided bombs mean that one carrier aircraft can now do the work of dozens. If you have an emergency somewhere, the smart bombs mean that you only have to send one carrier to take care of it, instead of two or three. With the surge doctrine, additional carriers will be ready to go if you need more help, or there's a problem somewhere else.
The ships most in need of this additional attention are the less publicized ones; the destroyers, cruisers, and smaller warships. The carriers and nuclear subs have always had priority on funds, and it was often at the expense of the other surface warships. Although the navy is still shrinking, the navy wants to make sure all ships that are still in service, can work as well as possible.