Archive for August, 2018

A Math Mistake in the News, decimal version

August 7, 2018

Last month there was a story on BBC.com entitled “Spain’s new submarine ‘too big for its dock'” (https://www.bbc.com/news/world-europe-44871788)

The main part of the story is that Spain’s new non-nuclear submarines were built too large for their docks.  (Hmmm.  Guess that was obvious just from the headline.)

The reason the submarines were too large is that they were redesigned to be bigger than originally planned.

The reason they were designed to be bigger than originally planned is that they were heavier than expected, and so the buoyancy was off, which for submarines is pretty important.  By the time that was discovered it was easier to increase the buoyancy by increasing the volume than by decreasing the weight.

And finally:  The reason that they were so heavy is that someone put a decimal point in the wrong place. According to the article “Navantia gets US help to fix overweight sub” by T. Kington (from http://www.defensenews.com in June 2013, but apparently unavailable now), the former director of the Office of Strategic Assessment at Spain’s Defense Ministry, said “I have been told it was a simple matter of someone writing in one zero when they should have written three.”  I put that in bold, because that small mistake, just twice zero, has taken years and millions billions of euros to (still not fully) rectify.  The contracts for four subs were signed in 2004, the first of the subs was nearly done in 2012 when the mistake was discovered, and now it looks like the subs are all dressed up with nowhere to go.  Poor subs – we look forward to a mathematically successful end to this story.

 

The submarine photo isn’t actually an S-80:  it’s a public domain photo of the USS Chicago (U.S. Navy Photo by Photographer’s Mate 1st Class Kevin H. Tierney. Edited by ed g2s). 

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