December 15, 2010: The U.S. Navy's 22 cruisers are cracking up. Over 3,000 cracks have been found in these ships, mainly in the aluminum superstructure and deck plates. For most of the decade, the cracks were just noted, and a year or more later, when it was time for the next shipyard overhaul, repairs were made. But now, some of the cracks are so bad, that ships have to be sent back to a port for repairs. The navy has been using this type of aluminum, which is an alloy containing five percent magnesium, since 1958. The problem was that eventually, the magnesium leaches out of the aluminum, which is now weaker and more subject to corrosion. Not a lot weaker, but enough. That's because steel will flex a bit to handle the stress of rough seas, while the aluminum won't, and eventually develops cracks. Lots of cracks. Meanwhile, the navy has a problem, as these cruisers are supposed to remain in service for at least another decade. The navy believes it can keep these cruisers in good repair, at an affordable cost, so they can remain in service. That's nice, because these are the last naval cruisers to remain in service. The Ticonderoga is the end of an era. No one else uses them anymore.

You could see this coming four years ago, when the United States sent its last all-gun cruiser, the USS Des Moines, to be broken up for scrap. The Des Moines was ordered during World War II, but did not enter service until 1948. It's displacement of over 17,000 tons, and armament of nine 8 inch guns, made it as powerful as some of the first modern battleships of 40 years earlier. The Des Moines class ships were the largest cruisers ever built. Russia has built some battle cruisers, carrying lots of large anti-ship missiles, and helicopters, rather than large cannon. But these are not traditional cruisers, and the Russians don't call them cruisers.

The modern cruiser was developed in the late 19th century, as a sort of "battleship lite." Cruisers were meant to maintain order in out-of-the way places, where hostile battleships were not present. Large and powerful enough to defeat any local warships, cruisers also became escorts for battleships, and later aircraft carriers, in the 20th century. But by the 1950s, missiles began to replace guns as the major weapons on warships.

The original cruisers displaced less than 10,000 tons, but by World War II, that had increased by 50 percent. Destroyers, which a century ago were small ships, displacing about 1,000 tons, grew to about 3,500 tons during World War II, and nearly 10,000 tons today. This weight inflation got so out of hand that, two decades ago, the U.S. Navy reclassified it's Ticonderoga class destroyers, which eventually displaced 10,000 tons, as cruisers. For a while, the U.S. wanted build a new class of 32 destroyers, the DD(X) (later called the DDG-1000 Zumwalt class destroyer), that displaced 14,000 tons. These ships are 180 meters (600 feet) long and 24.6 meters (81 feet) wide. A crew of 140 sailors operate a variety of weapons, including two 155mm guns, two 40mm automatic cannon for close in defense, 80 Vertical Launch Tubes (containing either anti-ship, cruise or anti-aircraft missiles), six torpedo tubes, a helicopter and three helicopter UAVs. At least one of these ships will be built, and maybe three. Costing over $3 billion each, they are just too expensive,

To put all this in perspective, consider that, a century ago, a Mississippi class battleship displaced 14,400 tons, was 124 meters (382 feet) long and 25 meters (77 feet) wide. A crew of 800 operated a variety of weapons, including four 12 inch, eight 8 inch, eight 7 inch, twelve 3 inch, twelve 47mm and four 37mm guns, plus four 7.62mm machine-guns. There were also four torpedo tubes. The Mississippi had a top speed of 31 kilometers an hour, versus 54 for DD(X). But the Mississippi had one thing DD(X) lacked, armor. Along the side there was a belt of 23 cm (9 inch) armor, and the main turrets had 30.5 cm (12 inch) thick armor. The Mississippi had radio, but the DD(X) has radio, GPS, sonar, radar and electronic warfare equipment.

The DD(X) would make quick work of the Mississippi, spotting the slower battleship by radar or helicopter, and dispatching her with a few missiles. The Mississippi's 12 inch guns had a maximum range of 18 kilometers, versus 130 kilometers for the Harpoon anti-ship missile. There has always been some debate if modern anti-ship missiles could really take down a battleship, what with all that armor and plenty of sailors for damage control work. We'll never know, but few warships have armor these days. The only exceptions are some large American aircraft carriers.

The designation "destroyer" has actually gone out of favor in most nations. Part of this is political correctness. Ships that, for a century, had been called "destroyers", are now usually called "frigates." Most American "destroyers" for the last few decades would be classified as "cruisers" for most of the last century. The proposed DD(X) is a 30 meters (100 feet) longer and 6 meters (20) feet wider than the current Arleigh Burke class destroyers. And with 50 percent greater displacement, weigh as much of World War II cruisers, and battleships of a century ago.

Moreover, the DD(X) will have half the crew of the Arleigh Burke destroyers it replaces. This will mean a lot more comfortable living conditions for the crew. This marks another major difference from 14,000 ton ships of a century ago. The Mississippi had most of the sailors sleeping in hammocks, tying them up during the day so there was room to sit down and eat. The Mississippi also had trough type urinals and unwalled johns in the heads, and salt water showers. Sailors spent a lot of time cleaning the ship, including scrubbing the deck and polishing and painting. The DD(X) accommodations will be more like what you would find in a cruise ship, and be built for low maintenance (including a stainless steel hull.)

DD(X) has four guns, the Mississippi had 48. But the Mississippi represented another milestone, it was the last of the "pre-Dreadnought" battleships. Warship designers in Britain and the United States had concluded that technology (longer range guns and better fire control) made it obvious that the next generation of battleships should put most of their firepower into the maximum number of the largest guns a ship could carry. While the British put their Dreadnought battleship into commission first (1906), the American USS Michigan, an 18,000 ton ship, was the first to be laid down. With eight 305mm (12 inch) guns and a top speed of 33 kilometers an hour, this type of battleship was the most powerful thing afloat until World War II, when aircraft carriers made battleships obsolete.

The DD(X) is still "pre" whatever the next dominant type of warship will be. But it's ironic that a hundred years later, the descendent of the 14,000 ton Mississippi is a 14,000 ton surface ship that has more firepower, a longer reach and the ability to see targets hundreds of kilometers away, and is called a destroyer. And what kind of destroyers escorted the Mississippi? They were ships of under a thousand tons displacement, with crews of about a hundred sailors. Armed with a few 76mm (3 inch) guns and some torpedoes, no one at the time expected them to evolve into a 14,000 ton warship.

What killed the DD(X) was size (too large) and cost (ditto). Today, the "battleship" is the aircraft carrier, and only a half a dozen countries can afford them. In fact, most of the world's aircraft carriers are possessed by one navy, that of the United States. For all other navies, their "battleship" is what the United States calls a "guided missile ship" (of either the destroyer or frigate variety.) The DD(X) is seen as a ship without a purpose, just as the Des Moines was. Thus the ship classes that evolved a century ago are fading away, to be replaced by something else. What exactly those new ships are is still unclear. It takes a war to decide such questions, and there have been very few naval wars since World War II.