Convenience of the metric system

[mikeguyver]

10 inches really means something...... Say 25.4 centimeters and she thinks of an eye dropper or the distance between a babies eyes....or how much cough syrup to take.....

[jongleur]

inchworm being called a centimeterworm?

No, but there is a millipede and centipede.

[K_V_B]

Originally Posted by Benz

Can't believe I have to explain this: If you divide a circle into two equal parts with a line, then divide it again into quarters with a line at right angles to the first, then wish to divide it evenly again, you must use TWO lines. Next even division requires four lines, and so on and so forth. If you keep dividing it so you end up with 180 lines across the diameters.

This doesn't make any sense. Each division requires a doubling of the number of lines.
So the next division after you've drawn four lines requires 8 lines. And then 16. And so on. Your total number of lines will always be a power of 2. According to this logic a circle should be 128 or 256 degrees, or even 512...

[Ex-Calif]

Originally Posted by HappyMdRSailor

Reminds me of something that happened the other day... One of the kids had a grammar paper with the statement of Chuck Yeager breaking the sound barrier at 1650 mph...???......???......???...

I said... That's not even close! Not ft/s, m/s, km/hr... not a typo... I grabbed a big red marker, circled it and put down a big red F!!! to turn back in...

Originally Posted by GordMay

Although Chuck Yeager broke the sound barrier in October of 1947, achieving a speed of Mach 1.06 (662 mph) ; he also became the first to exceed Mach 2, achieving Mach 2.4 (1650 mph) in December of 1953, flying the Bell X-1A .

Hmmm...

Effing a kid on an English paper for a physics "mistake" seems a bit harsh. Especially as the physics mistake may not be a mistake at all.

[Benz]

Originally Posted by K_V_B

This doesn't make any sense. Each division requires a doubling of the number of lines.
So the next division after you've drawn four lines requires 8 lines. And then 16. And so on. Your total number of lines will always be a power of 2. According to this logic a circle should be 128 or 256 degrees, or even 512...

Your problem, KVB, is that you theorize more than you do. Rather than theorize about how circles could be divided, try taking a ruler and dividing one into even sections by drawing lines across the center as I described. Once you have, I daresay it will make sense.
Sure, in a classroom you can use spherical geometry to do theoretical navigation in any units you please, but when the rubber meets the road (or the keel meets the briny), all that classroom theorizing goes out the porthole and the value of deg/min/sec, of nautical miles and fathoms, yards and feet becomes apparent. Do sight reduction tables even exist for navigating in UTM? I'll bet not. Is there a nautical almanac that gives ephemeris in anything other than right ascention and declination (in deg/min)? Never seen one. Theoretically, the Russians could have put men on the moon. Actually, they did not. There is a vast gulf fixed between theory and reality, and you evidently have not crossed it yet.
Charts are not in Metric. Why would you say something so stupid? Whatever paradigm they have now crammed datums into, most of the information on most charts comes from surveys that are centuries old in some cases. In Newfoundland the charts created by Captain Cook and later French whalers and explorers, who measured depths in fathoms (with a piece of string!) and had never imagined a UTM grid are in high demand, because they are in every respect better than the modern charts put out by the Canadian government with depths not re-surveyed, but converted to meters from Captain Cook's fathom soundings! At least they are still in degrees.....
My friend, the real world is a far cry from the idealized laboratory and classroom settings in which the metric system has it's shining moment. Let the scientists measure their milliamps and split their atoms in whatever unit they wish. We who have voyaged, and built, and gotten things done beyond theories will continue to do so the proper way.

[StuM]

Originally Posted by Benz

Your problem, KVB, is that you theorize more than you do. Rather than theorize about how circles could be divided, try taking a ruler and dividing one into even sections by drawing lines across the center as I described. Once you have, I daresay it will make sense.

Nope - there is no way that you can get 180 lines by repeatedly subdividing circle sectors in half. As KVB correctly points out - every time you subdivide, you double the number of sectors and the number of lines.

For a start, there will alway be an odd number of lines, so your claimed 180 lines is clearly impossible. That is obvious from your description where you start of with a single line (odd) and thereafter add an even number of additional lines each time (1+2 = 3, 3+4 = 7 etc)

You will progresssively get 8/16/32/64/128/256/512 sectors and 7/15/31/63/127/255/511 lines.

[El Pinguino]

Originally Posted by Benz

....celestial navigation ....in degrees/min/sec....

Seconds of arc??? Nobody uses seconds of arc.... since Noah was a deckboy degrees/ minutes/decimal minutes have been the norm.


OK ... the french were a bit slow... I still have some French charts ( singapore and thereabouts ) which use seconds in the lat and long scales.... which is odd considering that they gave us the metric system in the first place...

[sailorchic34]

Originally Posted by K_V_B

So you'd have a nautical mile that is completely arbitrary set to a particular length. And this is more useful because?

Hum, Not quite arbitary.

A nautical mile is equal to one minute of arc. 60 nautical miles is one degree. Of course a minute of arc is also equal to 1852 meters or 1.852km. which is not so easy to convert to minutes. I'll use nautical miles and knots. It's simple and based on a actual physical dimensional relationship. Not at all Arbitrary.

Perhaps the marine charts in Switzerland are metric. But not everywhere has a metric coastline like the swiss. Many places, the charts still come with degrees, minutes, seconds, or decimal degrees which no is not quite metric.

[sailorchic34]

Originally Posted by El Pinguino

Seconds of arc??? Nobody uses seconds of arc.... since Noah was a deckboy degrees/ minutes/decimal minutes have been the norm..

We can thank GPS for decimal minutes. Before that its was D.M.S. I did some drafting for a surveyor long ago, though well past noah's time and it was always D,M,S on the transit readings

That new fangled Decimal minutes will never catch on...

[avb3]

Originally Posted by twoblocktom

Both ways have there purpose. Example: if my friend in the Midwest says "it's only 12*F here." I can reply "it's 81*F here!" Or I can pause, think of his feelings, do a quick conversion, and reply "I know, it's only 27 here." And not cause him to question the decisions he has made for his life.


Sent from my iPhone using Cruisers Sailing Forum

Either way, right now it is cold here.

Celsius


Farenheit

[Alan Mighty]

Originally Posted by sailorchic34

A nautical mile is equal to one minute of arc. 60 nautical miles is one degree. Of course a minute of arc is also equal to 1852 meters or 1.852km. which is not so easy to convert to minutes. I'll use nautical miles and knots. It's simple and based on a actual physical dimensional relationship. Not at all Arbitrary.

That's (meaning 1 nM = one minute of arc) only close to physical truth around Latitude 48 degrees N.

There's much more of the planet than the band around 48N.

So it's sort of arbitrary.

Al

[Finistere]

You don't have to change your language. You can still walk in to a butchershop in Amsterdam and ask for a pound of ground beef. You'll get 1/2 Kg...

And an ounce is one hectogram or one tenth of a Kilo or 100 grams or 10 decigrams.

Learned metric as a kid, learned imperial when I was 14, had to relearn metric in the mid seventies in Canada, back to Imperial ( except for gallons) after moving to the U.S. I find imperial more natural especially when driving and doing estimates for arrival, at 60 mph usual average I will arrive in one hour. Millimeters are to small for most carpentry. Then there are the fifty cycles for generators which screwed up electric power compatibility all over the world, they could have left that alone.


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[sailorchic34]

Originally Posted by Alan Mighty

That's (meaning 1 nM = one minute of arc) only close to physical truth around Latitude 48 degrees N.

There's much more of the planet than the band around 48N.

So it's sort of arbitrary.

Al

Ah, love bowditch, and yes now it is, as defied by many intergovernmental committees. Though the original intent was that a nautical mile was one minute or arc on any meridian. It was not really a measurement in feet/meters but a measurement of arc. Still quite handy and yes I use it. That it varies depending on where one sails, worries me not at all.

[StuM]

Originally Posted by Finistere

And an ounce is one hectogram or one tenth of a Kilo or 100 grams or 10 decigrams.

An ounce is 30 grams ( well actually 28.3495 )

[El Pinguino]

Originally Posted by sailorchic34

We can thank GPS for decimal minutes. Before that its was D.M.S. I did some drafting for a surveyor long ago, though well past noah's time and it was always D,M,S on the transit readings

That new fangled Decimal minutes will never catch on...

Surveying ashore and possibly even surveying at sea when using a station pointer but practical navigators were using minutes and decimal minutes long before I went to sea which was long before GPS showed up.

I think Lecky in his 'Wrinkles' used seconds of arc.

Decimal degrees are truly evil things.......