Oct

8

Zumwalt-class destroyer

Originally, 32 ships were planned, with $9.6 billion research and development costs spread across the class. As costs overran estimates, the number was reduced to 24, then to 7; finally, in July 2008, the Navy requested that Congress stop procuring Zumwalts and revert to building more Arleigh Burke destroyers. Only three Zumwalts were ultimately built. The average costs of construction accordingly increased, to $4.24 billion, well exceeding the per-unit cost of a nuclear-powered Virginia-class submarine ($2.688 billion), and with the program's large development costs now attributable to only three ships, rather than the 32 originally planned, the total program cost per ship jumped. In April 2016 the total program cost was $22.5 billion, $7.5 billion per ship.

Henry Gifford disagrees with the implication:

I am no fan of runaway government spending, and waste, and stealing, but I applaud the decision to stop construction of the Zumwalt ships when it became apparent they were not what the navy wanted. It would have been better for the egos and careers of senior Navy officers to make believe the Zumwalt ships were desirable and keep making them, then quietly retiring.

The "peacetime" military has a huge challenge predicting what weapons will work well in the next war. At the same time, the military needs to maintain some shipbuilding capacity in the US, so that ships can be made in the US in the future. Maintaining shipbuilding capacity requires continuously building navy ships, needed or not needed, as the capacity to build ships in the future is critical. I haven't heard about anyone putting numbers on the value of this capacity.

Before WW2 the US has a robust shipbuilding industry that shifted to building navy ships, and ramped up for increased production. In the years since, that industry has gone away, except for a few pleasure boats and for military craft. One version I heard was that the last time ships were manufactured in the US installing a porthole required work by members of thirteen different unions, a problem presumably not faced in the places where the shipbuilding industry is robust today. With no significant shipbuilding industry in the US now, outside of military ships, the navy needs to keep building ships. (I think navy ships don't have many portholes, which probably avoids on of the challenges formerly faced by the commercial shipbuilding industry in the US).

One version of the Zumwalt story I heard is that much of the Zumwalt superstructure was made of Aluminum, to save weight, especially high up where saving weight increases stability and/or frees up capacity for mounting weapons high up, while the lower parts of the structure and hull were made of steel, and the dissimilar metals reacted with each other (happens quickly in the presence of salt water), resulting in terrible corrosion and structural damage. The Aluminum superstructure idea has been tried on naval ships before, but as Aluminum burns in a fire, it is not without risk to crew and ship in battle.

Another version of the story I heard is that the ship was designed for weapons which never materialized, thus the ships were cancelled. It all sounds logical, but somehow doesn't have the ring of truth that the version above has.

I also note that the Zumwalt ships were significantly larger than the Burke class ships made before and after it, and it seems quite believable (to me) that the navy simply wanted a larger number of smaller ships. Once upon a time the larger a battleship was the larger the guns it could carry and thus it had the firepower to shoot further than opponents, which meant it had the capability to maneuver to where an enemy was within range of its guns, while staying out of range of the enemy's guns. This battle-winning capability was worth the cost of huge ships. Now in the age of missiles and radar, the size of a ship is not nearly as relevant. During WW2 German soldiers reportedly said "one of our panzer tanks is worth ten of those American Sherman tanks, but every time we build one panzer they build eleven Shermans". As tank-on-tank battles were not the main, or main intended use of tanks, eleven OK tanks had many, many advantages over one superior tank. The US Navy might have decided that for similar reasons they are much better off with a larger number of smaller ships than a smaller number of Zumwalt ships. I would be surprised if the actual truth about the decision is ever made public, and more surprised if I was ever convinced that I was convinced the real reason(s) was made public.

The math about per-unit cost when development cost is amortized over the number of units produced is, I think, useful, but implies that development cost for something that never saw production or only went into limited production was somehow wasted.

The US navy now has hard data on the seakeeping ability of a full-scale tumblehome hull ship design, which I think nobody had before the Zumwalt actually went to sea. No, testing a scale model is not a robust test because much in fluid dynamics does not scale (google "Reynolds Number"). And if computer modeling alone was good enough nobody would have wind tunnels. The history of airplane development is full of planes that were built and flown in very small numbers, with the data helping to inform future designs. As the Zumwalt was such a radical design, departing so far from normal shipbuilding experience and formulas (google "metacentric height", "center of buoyancy", and "center of gravity"), it, I think, deserves to be thought of in much the same way as plane designs that saw very limited production and saw testing, and informed future designs in a useful way.

The US navy also has hard data on the radar signature of a tumblehome hull design, which nobody else has unless they pointed their radar sets at a Zumwalt class ship while configured for battle. I somehow doubt the US Navy sailed the Zumwalts close to the coast of Russia unless they added radar reflectors to them to mask their actual wartime radar signatures.

Maybe someone on the list developed and tested a trading strategy and found it lacking, then used the insights gained to test another strategy that turned out to be useful. Was the cost of developing and testing the first strategy wasted? I think not.

Carder Dimitroff writes:

Henry, your comment about aluminum reminded me of nuclear power plant design. For the reasons you state, aluminum is not allowed inside the containment (reactor building). Copper and stainless steel are used in place of aluminum. Outside the containment, aluminum is everywhere. I assume the US Navy requires similar standards for their nuclear submarines and aircraft carriers. Many design features in commercial nuclear plants originate from the nuclear navy.


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