An American aircraft carrier, the USS George H.W. Bush (CVN 77) entered service in 2009 and made several normal deployments overseas since then. But there was a problem with the innovative new plumbing system that moved the crap put into 423 toilets and urinals (in 130 "heads", which is what sailors call bathrooms). The new VC/MSD (vacuum collection/marine sanitation device system) was, on paper, an improvement over older VCHT (Vacuum Collection Holding Tanks) sewage disposal equipment. The VC/MSD as installed in the USS Bush has not worked well, and six percent of the time some or all of the toilets are not working (will not flush). This has caused much unhappiness on the carrier. The Bush was sent to a shipyard in June 2015 for a six month modification that would enable the use of both the fifty year old VCHT system as well as the new one. This had never been done before and it took longer than expected and was not completed until July 2016. Now there are more delays in necessary shipyard work and the Bush may not make its December date to relieve another CVN overseas. The Bush delays have already interfered with the training schedules of other carriers. Officially all this was just bad luck but many veteran navy personnel blame the persistent (for decades) problems of mismanagement at the navy shipyards and the refusal of senior political and navy leaders to deal with the problem.
The same attitude caused the navy leadership to initially blame the VC/MSD problems on sailors trying to flush large objects (tampons, clothing, socks, paper and such). That sort of thing is always a problem, but on the Bush, the new plumbing system caused clusters of toilets (sometimes half the ship, or all of the ship) to stop flushing when there is a blockage. And there have been a lot of blockages, far more than in earlier systems. During its first three years of service over 10,000 man-hours were spent on fixing the toilets (or, more precisely, finding out where, in the 400 kilometers of plumbing, the jam was and clearing it.)
Despite years of problems the navy insisted it was working on a solution and that the toilets were available 94 percent of the time. But that meant six percent of the time the toilets were not working. And in one epic failure, the entire ship was without a working toilet for 34 hours. For the crew, this was not acceptable but for the politicians and senior admirals who authorized this bit of progress it was a minor problem. The 5,000 sailors on board CVN 77 have wasted over a hundred thousand man hours looking for some place to pee or take a dump. Much time was also spent fretting over whether to skip a meal or a drink of water, because the heads were not working, or were not expected to be.
The same VC/MSD system was also installed in destroyers and large amphibious ships (that look like small carriers) without these problems. The navy and the VC/MSD manufacturer refused to comment on what the cause, and solution, for the problem should be. That has not helped morale on the Bush either, leaving the sailors without a pot (or head) to piss in. By 2015 the navy gave in and approved the VCHT fix. Unfortunately that turned out to be a fiasco as well and the crew of the Bush are not optimistic that the VCHT mod will work. Officially the navy insists that it will, but they always say that.
The Bush was the last of ten Nimitz class carriers. The first one 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 developed equipment. This stuff was installed in older Nimitzs eventually, as they went in for maintenance. The Bush, the last of the Nimitz class, 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 replacement for the Nimitz class, the Ford class, was supposed to have its first ship the USS Ford (CVN 78) in service by 2015. That has been delayed over a year and is now scheduled to enter service in late 2016. CVN 21 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 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 build), the Fords will feel, well, kind of empty. Lots more automation, computer networking and robots. The Bush has a lot of this automation already and the crew being assembled for the Ford are wary of the new gear they will have to deal with.