Naval Air: The Dry Dock Is My Friend


October 26, 2009: A four decade long construction effort ended earlier this year when the tenth, and last Nimitz class carrier, the USS George H.W. Bush (CVN 77), completed its sea trails and was accepted by the U.S. Navy. The first Nimitz class carrier entered service in 1975, and is currently set to serve for 49 years before decommissioning. All of the Nimitz class carriers are similar in general shape and displacement. But over four decades, each new member of the class received recently newly equipment. This stuff was installed in older Nimitzs eventually, as they went in for maintenance.

There is a lot of maintenance, enough to keep these carriers unavailable for over 20 percent of their career. Over its fifty years of service each Nimitz class carrier has 17 planned trips back to the ship yard. There are twelve Planned Incremental Availability (or PIA) operations in which new gear is installed, worn or damaged stuff is replaced and any heavy duty work needed, is completed. Duration of a PIA varies with the amount of work to be done, but it can take several months, or a year or more.

Even more lengthily are the four Dry-docking Planned Incremental Availabilities (DPIA) operations, which are more extensive PIAs that include putting the ship into dry dock. These efforts can last a year or two. The one Refueling and Complex Overhaul (RCOH) is like the DPIA, except the ship is partially dismantled so that the spent nuclear fuel can be replaced. This takes a little longer than your usual DPIA, and often costs over half a billion dollars.

The Bush has a lot of new gear that wasn't even thought of when the first Nimitz entered service. The first ship of next class of carriers, the USS Gerald R Ford (CVN 78) will be about the same length and displacement of the Nimitz ships, but will look different. The most noticeable difference will be the island set closer to the stern (rear) of the ship.

The USS Ford, is expected to cost nearly $14 billion. About 40 percent of that is for designing the first ship of the class, so the actual cost of first ship (CVN 78) itself will be some $9 billion. Against this, the navy expects to reduce the carriers lifetime operating expenses by several billion dollars because of greatly reduced crew size. Compared to the current Nimitz class carriers (which cost over $5 billion each to built), the Fords will feel, well, kind of empty. Lots more automation, computer networking and robots. The Bush has a lot of this automation already. A lot of the new gear in the Fords will find their way into the other Nimitz's via RCOH, DPIA and PIA.

By the time the Ford enters service in 2015, even more of the crew will be replaced by robots than is the case in the Bush. The Ford will have about half as many sailors on board. Carrier based UAVs are also under development. Work on flight control software for carrier operations is well underway. Combat UAVs (UCAVs) weight about 20 percent less than manned aircraft, and cost 20-30 percent less. They use less fuel as well.

While the navy would prefer to design and build the first generation UCAVs for use on existing carriers, these smaller and cheaper aircraft go together well with smaller and cheaper carriers. This means the Ford class may be the last of the big carriers. That's because UCAVs mean you can get more aircraft on a carrier, and that creates a traffic jam type situation. Moreover, the widespread use of smart bombs means you need fewer bombers over the target. A 50-60,000 ton carrier, with three dozen F-35Bs, UCAVs, UAVs and support aircraft, can be as effective as a Nimitz with 70 F-18s and support aircraft. Thus the Ford class may not completely replace the Nimitz class on a one-for-one basis. The sharply rising cost of building American warships may force the adoption of a smaller, cheaper, carrier class. Much like the Seawolf subs were replaced by the Virginias and the DDG-1000 is being replaced by, well, something smaller and more affordable.





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