HSLA 65 carrier weight-reduction study

NAVSEA-funded million-dollar Newport News study finding 2,000-ton weight savings possible by substituting HSLA-65 for 50 ksi steel on Nimitz-class carriers. Tom's punchline: his "10× material cost" rule of thumb predicts the same answer. Also frames the broader Nimitz weight-creep problem (250 tons/year) and the $50M cost of designing a new hull.

Then add the fact that all your cutting — you're not going to use everything in nice rectangular sheets, you don't get 100% yield in the shipyard. You've got a lot of scrap left over after you cut paper dolls out and weld them together. The actual cost per pound fabricated is about ten times the cost of the material you started with. The Navy did a million-dollar study down at Newport News. They were looking to reduce the weight of aircraft carriers. The Nimitz-class carriers have been around for fifty years. Why don't we have a new hull design? Because it would cost $50 million — this was twenty years ago — to design a new hull before you even build it. Just to design the shape of a new carrier is a $50 million bill. All the towing-tank stuff, the things you guys come back to learn how to do — they want you to do it for fifty cents. You'll have a summer over at Draper where you get to design a ship. It probably won't be a Nimitz replacement, but anyway.

Million-dollar study Newport News did for the Navy on substituting 65 ksi HSLA steel for traditional 36/50 ksi. Tom's example of the "materials are 10% of manufactured cost" rule playing out in a Navy procurement study.

Around 2000 they gave a million-dollar contract to Newport News Shipbuilding to do a feasibility study: what if they used a 65 ksi strength steel rather than a 36 ksi or 50 ksi steel, which was traditional shipbuilding? What if they went to a higher-strength steel — how much weight would they save, and what would be the total savings? At that time HSLA-65 steel cost about a dollar a pound, two thousand dollars a ton for the plate. They determined that manufactured, it would cost them ten dollars a pound to fabricate the steel. The material cost was ten percent. I could have done that for less than a million dollars. I would have given them that report for half a million. It's just a rule of thumb, and these rules of thumb are not bad.

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