In the UK, tyre pressures are expressed in both PSI and BAR. A tyre that takes 32 PSI needs 2.2 BAR. Most people still talk about miles/gallon but the car adverts all show economy figures in litres/100 km. Here a compromise of miles/litre would be most convenient since most odometers are in miles and fuel is sold in litres.
Just wanted to pop in and say that I’ll be using the “Old” system for a long time.
I fly in feet (AGL or MSL) and at Flight Levels based on multiples of thousands of feet. The only place in the world that I’ve used meters for altitude was over the former Soviet Union.
Even in France height is in feet and Flight Levels, and distance is in nautical miles.
Fuel for us is still given in pounds, but metric countries use kilograms. And converting units bites everyone sometimes: witness the Gimli Glider.
I don’t see aviation changing to metric anytime soon. 1,000 feet of vertical separation is not only a nice round number, but also seems to balance safety and efficient use of airspace quite nicely.
YMMV, of course. (Or is that Ykm/100LMV?)
Measure Nazis.
Wha??
Many folks claim that conversion would require re-education. In fact, though, it would just require education, since most Americans don’t know their units in the first place. I’ve seen people who think that an ounce is bigger than a cup, for crying out loud. And how many people know how many square feet there are in an acre? Or gallons in a barrel, or tablespoons in an ounce? But even allowing for a modicum of understanding (8 ounces to a cup, 2 cups to a pint, 2 pints to a quart, 4 quarts to a gallon, and a pint of water weighs a pound), there are still a lot of conversions which most folks don’t know. If I have a fish tank that measures 12 inches by 18 inches by 24 inches, how many gallons of water will it hold? This question is, for practical purposes, impossible in the customary system. In fact, the easiest way to answer it is to convert the inches to centimeters, calculate the liters, and then convert liters back to gallons.
I must point out that the United States already has adopted the metric system of weights and measures.
That’s a federal statute–Public Law 39-183–signed into law, I believe, by President Andrew Johnson in 1866, so we’re not talking about an international convention.
I mull over this when I try to convert tablespoons into cups, pints & quarts when measuring liquid, for example.
There is one drawback to the metric system, which seems to be the advantage of your confusin’ merkin [ask Cecil whether that’s an R-rated Word! :D] system. It’s the number 10. It has only 1, 2, and 5 as factors; 12 has 1, 2, 3, 4, and 6.
This is especially noticeable in Celsius temperature readings (OK, so I know that’s technically not a “metric” measurement), since the Celsius boiling point of water is 100. That number has 1, 2, 4, 5, 10, 20, 25, and 50 as factors, whereas 180 (boiling to freezing in Fahrenheit) has 1, 2, 3, 4, 5, 6, 9, 10, 12, 15, 18, 20, 30, 60, and 90.
Actually, there’s a somewhat easier way, although most people don’t know what it is. Multiply the dimensions of the tank out and then divide by (this has to be the most unusual integral conversion factor in any system) exactly 231.
That’s right, the definition of the US gallon is 231 cubic inches. How they came up with that, I don’t know, but it goes back about 3 centuries or so. It’s also known as the Queen Anne gallon, I believe. BTW, this doesn’t work with Imperial gallons, as the definition of that is the volume of 10 pounds of water at 62[sup]o[/sup]F.
Or ‘a pint of water weighs a pound and a quarter’ - or it does in the UK, anyway.
So much for “a pint’s a pound the world round” 
One of the key factors here is that people in their everday lives do not really need or care about metric measures. It doesn’t really matter whether you want to buy 1 gallon or 2 liters - it won’t really help anyone. So the entire question is irrelevant for most industries anyway, and even many scientific or engineering concerns have no real need to worry about metric. Does it truly bother people that I like miles rather than klicks?
Actually, that’s my key point of contention: as long as we have miles, inches, pounds, and gallons, I really don’t care what you do. I just love those particualr measurements. I also despise metric advocates who try to make it out that I am stupid and ignorant for not using it. The thought that I am making a rational choice for me is apparently much to complex for their brains. It seems their skulls are filled with metric measures instead.
And the irony is I know all the metric measures (well, I did. I’ve sort of forgotten some fo the unusual ones). But using them offers me no advantage in my life, therefore I don’t much think about them.
The real key is that the major benefit of the metric system, ease of calculation, is no longer a real issue with the advent of computers. With that issue off the table, the other benefit of the system, interoperability with the rest of the world, becomes significant – critical in some cases – in certain segments of industry.
However, for the average man-on-the-street, the benefit of switching may well no longer outweigh the costs of doing so.
That issue may fall with computers also. If data is properly tagged with units, then the software can handle any quantity in any units and convert automatically. That may be wishful thinking, but maybe not.
I took my wife for an ultrasound on Monday. The nurse told us our bundle of joy is 5 inches long and has a foot that is two centimeters in length.
I think that’s the way things are in America. Both systems are used so frequently they are both commonplace. You drive miles, but you run kilometers. Milk comes in gallons, but pop comes in liters. So on and so forth.
The one thing not catching on is the Celsius temperature scale. Common folk don’t dig the C scale and the Kelvin scale is more logical for use in science.
Mentock, autoconversion based on tagged numbers is trivial, assuming you bothered to record the units in the first place.
When you don’t, conversion becomes a matter of guesswork. And we all know how well that works.
Anyway, at the edges of our direct perceptions (very large or very small especially), metric works because it’s what scientists use and the unit-prefix system lends itself to trivial order-of-magnitude shifts.
But an inch is very close to the distance between the first and second joints of my right index finger. A pound is an extra-large can of something. The standard system is the standard we use to think about the world on a day-to-day basis.
Everyone records, somehow, the units in the first place (or the data is immediately worthless ), and yet the problem remains. The solution is straightforward, if that’s what you mean, but then so is world peace.
I’ve seen people reason thus: there are 16 ounces to the pound; ergo, my one cup of water weighs half a pound. The worst part there is that that weight is approximately correct, but they have no idea that they’ve mixed units for weight with units for volume. They might also reason that a cup of nails weighs a pound, and not understand the flaw.
For what it’s worth, I wish my industry would convert, or at least use the same units in design and construction. I design my stuff in decimal feet, but I have to convert it to feet and fractional inches (to the 1/8"). I wonder how many errors there are per year, and what the related costs might be…
Hey, I thought it would be neat to create an inch/feet/furlong/mile system which goes 1 mile = 5 furlongs = 5000 feet = 50000 inches. With the attendant changes and additions to make everything square away thereafter. Then we would have a competitor system. And hey, I thik that for a few hundred mil, we could convert most of Africa and SOuth America to our new units… Mwah ha ha!!!
You measure things in terms of the distance between joints in one of your fingers? Anyway, my right index finger happens to be about a centimetre thick, so there. And the description “extra-large can of something” is so vague that it could apply equally well to kilograms. Pints vs. litres, let’s see… oh yes: you can drink a pint of water in one go, but not a litre (unless you’re really thirsty). But so what? That arbitrary observation somehow makes pints more natural?
I plan to decimalise time itself; a day consisting of ten NewHours of morning and ten NewHours of afternoon, each NewHour made up of 100 NewMinutes, each NewMinute made up of 100 NewSeconds. 36 and a half NewWeeks, each consisting of 10 days per year. Seven day work weeks, three day weekends. Date/times will be written YYYY/WW/DD. There is no need for months.
I still maintain that there is no cost of switching. The typical American does not know metric units, but neither does he know American units. And most people to whom measurements are actually important do already know the metric system, even if they don’t use it.
Mangetout, somebody beat you to it. In the paperback Like MAD, Donald Knuth (who later compiled a serious series of computer manuals) came up with a totally decimalized system of weights and measures, which included “1 average rotation of the earth=1 clarke (cl).” this was divided into thousandths, hundredths, and tenths; and multiplied into tens, hundreds, and thousands. This went together with the “DATE” measurement, whereby the " year" was 100 days long and divided into 10 decimal months, each with 10 decimal days (cl.). The months were Tales, Calculated, To, Drive, You, In, A, Jugular, Vein. 