Unlicensed Engineers, Part 1 By Hendrik Tennekes

Unlicensed Engineers, Part 1

By Hendrik Tennekes

In the series of Weblogs I am now starting, I will lay the foundations for a theory of climate software development. I am of the opinion that most scientists engaged in the design, development, and tuning of climate models are in fact software engineers. They are unlicensed, hence unqualified to sell their products to society. In all regular engineering professions, there exists a licensing authority. If such an authority existed in climate research, I contend, the vast majority of climate modelers would vainly attempt certification. Also, they would be unable to obtain insurance against professional liability.

I am an unlicensed engineer. I was an engineering professor for many years, but I never needed to be certified as a Professional Engineer. One advantage of my University position at Penn State was that I did not need to purchase any liability insurance, which would have absorbed a sizable chunk of my modest salary.

I am also an unlicensed model builder. I have many years of experience as the builder of model sailboats based on wooden shoes, and I also contributed fresh insights in the scaling laws of sailboats, but those feats by themselves are not enough to qualify for certification. My saving grace is that model sailboats are toys, with little or no impact on the welfare of society.

Two of my favorite clog sailboats are the heroes of my story today. I renamed the black sloop with red sails two weeks ago. I had christened her Hella, in part because of the hell I’ve gone through since I was forced into early retirement. But now her name is Dallas, in honor of Roger Pielke’s superb webmaster, Dallas Jean Staley. The white schooner is called the Flying Dutchman, in memory of the threemaster skipper Willem VanderDecken, who swore at Cape Horn that he would fight the fierce headwinds he encountered until Doomsday if necessary, rather than seek refuge in a nearby bay.

dallas-at-flank-speed.jpg “Dallas”

the-flying-dutchman.jpg “The Flying Dutchman”

Both clogs have a waterline length of one foot, unsurprisingly so because human feet slip into them. Their masts are about a foot long, too. Their sail area is on the order of 90 square inches, and their weight is about 2 pounds. Their “immersion ratioâ€?, that is, their water displacement divided by the cube of their waterline length, is four times as high as in full-scale sailing yachts. This is the major fudge needed to obtain acceptable performance in the water. As a fudge, it is comparable to the excessive numerical viscosity needed in climate models in order to suppress unwanted instabilities.

My fudge consists of one pound of roofer’s lead wrapped around a length of carbon piping. Unlike full-scale flat-bottoms, my sailing clogs need this heavy keel to make them self-righting. A gust cannot topple them, no matter how strong it is. Their sails may get wet, but that does not deter them. Not all bystanders are convinced when they see me carry one of my sweethearts, but a quick experimental demonstration makes them believers. I just throw the clog upside down in the water. That quiets them. The proof is in the throwing.

As to the tuning of my models, the major problem there is that very few people understand the difference between a stabilizer and a rudder. A rudder does not provide directional stability to a ship unless it is locked in a fixed position. In the town I grew up in, fathers converted worn-down clogs into toys for their kids, and took pride in constructing a plywood rudder hung off hook-and-eye hinges. Kids liked that, naturally, because they could play helmsman in their daydreams. But this doesn’t work at all. I dare any climate modeler in this audience to provide a scientific explanation why.

My models need to be tuned. I am an engineer; I do that experimentally. I take them one by one to a large pond, a canal, or a quiet river arm, and try them out there. In earlier years, it occurred often enough that I had to sew a new set of sails, but these days I merely have to lengthen or shorten one or two sheets. For those of you not familiar with yachting jargon, sheets are the ropes by which a sailor trims his sails.

Look, I am not perfect. Occasionally, a newly-finished model on its maiden trip escapes me in an unexpected direction. Once or twice I had to come to the rescue by skinny-dipping and swimming in order to retrieve them. The laws of hydrodynamics are in my favor then: the “hull speedâ€? of surface vessels is proportional to the square root of the waterline length, so I can swim faster than they sail. Not much faster, but fast enough.

In the second part of this series, I will analyze one of the cornerstones of engineering. It is, in Karl Popper’s unforgettable words:

“We can learn from our mistakes.â€?

Yes, we can, but do we?
And will climate modelers ever learn?

Those of you who are eager to prepare for Part 2, do get hold of a copy of one of the books by Henry Petroski. My favorites are “Success Through Failure – The Paradox of Designâ€? and “Invention by Design – How Engineers Get From Thought to Thingâ€?.

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