
Why is the US still using imperal units? - jrwoodruff
http://www.newscientist.com/article/dn17350-nasa-criticised-for-sticking-to-imperial-units.html
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btilly
The metric system is simpler and better than the imperial system in every way
but one. And that one is that there are more 12s or multiples of 12 in the
imperial system, and so it is easier to split imperial measurements of every
day measurements into thirds and quarters. And that is frequently very
convenient. (The champion of divisibility is the acre, which is 2 _2_ 2 _3_ 3
_5_ 11*11 square feet.)

~~~
eru
When you have a numbering system based on 12, you have a few more factors to
treat in a special way. Why stop there? We can go to a numbering system based
on 60 or 72 or ...

Believe me, this is the wrong way. We should strive to avoid special cases,
and not create new ones. Thus - for the sake of consistency - we should build
our number system (and measurement units) on base 11. This way all (non-
trivial) factors will be treated the same way.

Since you have to deal with repeating fractions anyway, you might as well make
it the only case.

I rest my case.

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axod
This annoys the hell out of me.

Metric is worse in almost every way for day to day tasks. Not everyone is a
scientist doing complex calculations. For science, maths, engineering, sure
use metric.

Imperial measurements are based on convenience. Why do we buy a dozen rolls
from the baker and not 10? So we can divide them between 2,3,4,6 people.

Weights are similarly based on what is useful. Look at a recipe for cakes and
you might see 1Lb of this, 1/2Lb of this. The metric equivalent? 100g of this,
200g of that. How is that more useful to me?

You can easily divide imperial weights by 2,4,8,16 to make smaller batches.
Doing the same with metric is a pain.

Why do we ask for some 2 by 4 timber? Because it's easier than asking for some
48mm by 96mm timber.

If you're doing finer work, measuring things in divisions of an inch makes
perfect sense. 16ths of an inch means you can subdivide with ease. Try
dividing a cm into 8 equal parts sometime and tell me how you get on.

Why do we use shoe size numbers rather than specify the length of our feet in
mm? Because shoe sizes are about the right precision.

In the UK, we also use stone to measure our weight. I'm 9 stone and a bit. Why
is it more useful to be able to say I'm, 60kg. That's more precision than I
want to tell someone my weight.

I know this is an unpopular view with geeks, but if someone could please
explain what problem metric solves, I'm all ears (And please don't trot out
the space shuttle imperial vs metric mix up FUD).

~~~
eru
> Why do we ask for some 2 by 4 timber? Because it's easier than asking for
> some 48mm by 96mm timber.

Only, you wouldn't. For the same reason you do not buy 2.11337642 pints [0] of
milk. The metric system is convenient enough to work in daily life. (But the
historical baggage it contains annoys me. For example the we should get rid of
the Kelvin and use a unit of temperature that makes the Boltzmann constant
have a numerical value of 1. Also the Mol should make way for a sensible unit
of number of atoms, like 1. Oh, and the speed of light should be made some
simple number, too.)

I guess with the advent of computers the difficulties of calculation with
imperial units should not matter any longer. So imperial units are just not
inconvenient enough to warrant a change. Like SI units are not inconvenient
enough to warrant a change to something even simpler.

On the subject of choosing dimensions
<http://en.wikipedia.org/wiki/Preferred_number> has some interesting things to
say.

[0] 1 Liter = 2.11337642 Pints

~~~
axod
You missed my point though... People use 2x4 timber because it's a useful size
of timber to use. And they use inches because they're useful in describing
that. mm/cm/m are less useful for that use case.

~~~
seanx
100mm * 50mm is what I buy. Or 10cm * 5cm. It's not that complicated.

~~~
axod
I didn't say it was complicated anywhere. I said it was less useful and
unnecessary.

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tjic
"If the question begins, 'Why don't they…?' the answer is money."

\-- Robert Heinlein

~~~
yannis
Pity!

From the Mendehall Order of April 5, 1893

... such action will also have the great advantage of putting us in direct
relation for our weights and measures with all civilized nations, most of
which have adopted the metric system for exclusive use.

<http://physics.nist.gov/Pubs/SP447/app3.pdf>

I am actually convinced that if all costs are properly factored in, it will be
more than beneficial in the long term. It is not that bad, I lived through a
transition and it was almost uneventful!

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Kaizyn
About 15 years ago now, I remember watching a PBS news show where this
question came up. One of the guests said that we would never leave the
Imperial system because all the land in the US was surveyed and alotted in
Imperial. The switching costs away from that were deemed too high.

~~~
jrwoodruff
Funny you mention that - it's actually how I got on this tangent. according to
wikipedia:

"Twenty-four states have legislated that surveying measures should be based on
the U.S. survey foot, eight have legislated that they be made on the basis of
the international foot, and eighteen have not specified the conversion factor
from metric units"

Yea. Survey foot. That's not even the current international standard for the
length of a foot. Ridiculous. Glad I'm not an interstate contractor that has
to deal with this mess.

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jrwoodruff
I know this is an old-ish article, but this is a topic that severely annoys
me. I was taught both systems of measurement, beginning in grade school. But I
still have to calculate feet and inches. I have to buy twice as many tools for
my garage, because that bolt could be 3/4" or 17mm. NASA can't even manage to
build the space shuttle replacement using the metric standard? wtf?

~~~
byoung2
I find it hard to believe that it would cost $350 million to convert the
drawings and diagrams to metric. I would do it for half that price!

~~~
jrwoodruff
Even if it did cost that much, did they learn nothing from the mars orbiter
disaster? Pick a standard unit and stick to it. And make damn sure all your
contractors use the same unit. Seems like the unit that every single country
in the world is on would be a good one to choose.

~~~
yannis
If my memory is correct something very similar happened also during the
testing of the first 'Star Wars' missiles. The given cost is pure bull.
Autocad has a facility where one can convert from metric to imperial
dimensions. It would not cost that much to re-design the software to carry out
the conversions automatically, including re-selection of standard components.
(Except if NASA is still using rotring pens and tracing paper).

One issue that would crop up though is some very odd looking sizes. Assume a
rod of 1". This will translate to 25.4 mm, no sane Engineer in the rest of the
world would specify a size like this, but would go for 25.0 mm.

Having studied both systems I can assure you that the Imperial System adds
easily 6 months to an Engineer's training.

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tjic
Why do we "still" use binary / hex for computers?

The answer is that a decimal system of notation isn't a pure win in every
endeavor.

As a woodworker, there's a lot that I like about Imperial (I like doing
metalworking in metric, though, and I have one metalworking lathe calibrated
in each system).

In woodworking, an inch is about the width of my thumb pressed flat. I can
quickly measure things that way. The foot is a convenient size for the work
that I do. Meters are a bit too big. Centimeters are too small. Imperial drill
bits are available in sizes related by n/2. I can go from a 1" bit to a 1/2"
to 1/4" to 1/8", etc. Or, I can add 50%, going from 1/8" to 3/16".

See also ISO preferred numbers (ISO 3:1973)

<http://en.wikipedia.org/wiki/Preferred_number>

<http://www.sizes.com/numbers/preferred_numbers.htm>

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JCThoughtscream
Sheer bloodyminded cultural momentum has a lot to answer for.

Thankfully, excepting the occasional conversion flub from NASA and structural
engineers, Americans that need to use the metric system usually know how to
use the metric system. So don't dismiss quite all of us as backwards wankers
quite yet...

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moron4hire
Here's the thing that I find tragically hilarious about this conversation: you
can't get people this riled up about their local school superintendent
embezzling money.

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moron4hire
The question is, what is the benefit of switching? "It's easier." Yes,
technically metric is easier than imperial... _but imperial isn't that hard_.

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TNO
"The metric system is the tool of the devil! My car gets 40 rods to the
hogshead, and thats the way I likes it!" -- Abraham Simpson

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ecq
the cost of converting outweighs the benefits according to some people.

~~~
varjag
That's until you lose another space probe or two.

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jacquesm
Lawyers.

edit: hey downmodders, seriously, the answer _is_ lawyers.

The legal mess that would ensue from having to switch the land measurements to
metric is one of the biggest stumbling blocks, the lawyers would have endless
causes to bicker over the exact location of property boundaries.

Never mind that the inch is defined as 0.0254 meters.

~~~
wglb
_the answer is lawyers._

Not really.

My uncle was a farmer, which in these days involves mostly machinery, which
all have bolts. Back then, there was talk of converting to the metric system,
and he said that he hoped that he would be able to retire before that came
into being. But then he bought a New Holland combine, which was all metric.

At that time, I think there was a proposal to allow mechanics to get a tax
deduction for replacing all there tools with metric tools, but this was
denied.

Similarly the cost of conversion is huge for NASA and many other industries.

Property boundaries are, except for Texas, I hear, are all based off of
reference points that are precisely described.

So I don't think the answer is lawyers.

