UNITS OF MEASUREMENT U.S.NAVY

[Rockin Robbins]

Originally Posted by merc4ulfate

All units of measurement which come from humans are born out of arrogance since none of them take into account universal laws and constants of measurements. None of them reflect the inaccuracy of vibration bodies which make up the world the arrogant thought came from.

So outside of that I suppose the the least inaccurate measurement would be based on 1 Arc second but no one has decided to use that one as yet either. Although some skippers in WWII did actually use the Arc second they did not know what it was they were really doing and was calculated in their brain and not by a slide rule.

You call it leading the target by use of guesstimation based on visual inputs and estimations of forward momentum.

It is still an Arc second however.

And here I am, crippled on my cell phone again. I can't leave this one uncommented on but it deserves a thoughtful response. I'd end up shooting the cell phone, drenching it with gasoline, lighting it on fire, running over it with my van, tossing it into a trash compactor and deep sixing it in a vat of battery acid.

I'll wait till tomorrow...

[Rockin Robbins]

Originally Posted by merc4ulfate

All units of measurement which come from humans are born out of arrogance since none of them take into account universal laws and constants of measurements. None of them reflect the inaccuracy of vibration bodies which make up the world the arrogant thought came from.

So outside of that I suppose the the least inaccurate measurement would be based on 1 Arc second but no one has decided to use that one as yet either. Although some skippers in WWII did actually use the Arc second they did not know what it was they were really doing and was calculated in their brain and not by a slide rule.

You call it leading the target by use of guesstimation based on visual inputs and estimations of forward momentum.

It is still an Arc second however.

Okay, let's tackle this very interesting post. Sentence one gets a pass but contains strangeness. Sentence 2 is incomprehensible as "the inaccuracy of vibration bodies which make up the world" is an undefined phrase. I guess it's a Rorshach blot.

It's the second paragraph "I suppose the the least inaccurate measurement would be based on 1 Arc second but no one has decided to use that one as yet..." Did some skippers in WWII actually use "the arc-second" and did they really "know what they were doing?"

What's an arc-second? One degree (a small enough angle, but twice as much arc as the diameter of the full moon) can be divided into 60 minutes. THAT arc-minute can be subdivided into 60 arc-seconds. So, doing the math, one arc-second is 1/60x60 or 1/3600 of a degree. You can't measure an arc-second on a periscope. You can't read one off a stadimeter. Or a sextant. Nor can you read one off any charting tool in the arsenal or enter one into a TDC.

These puppies are just too small to be of any use to anyone but an astronomer (of which I happen to be an amateur astronomer, and no, none of my instruments can measure an arc-second either.) Now my 13' telescope, the same size as that which discovered the dwarf planet Pluto, has a theoretical resolution of about .3 arc-seconds. But two stars an arc-second apart don't appear to be two dots with black between them. They are two lobes of a dumbbell, with the connection between them dimmer than the stars themselves. That's called resolved: that you can tell that there are two objects there, even if you can't separate them with black space. So, if I had a reticle in my 13" telescope at a high magnification and calibrated in arc-seconds could I measure arc-seconds? Sure.

But nothing in the class of my astronomical telescope existed on a World War II telescope. If it did, it would have been totally useless. Telescopes don't just magnify size. They magnify movement too! Suppose your submarine is in calm water and you have a 15x binocular in your TBT. If the submarine is rolling only 5º with a period of ten seconds, plenty gentle to be able to follow things with your naked eye, in the TBT they're moving 75º back and forth! Where to the naked eye they're only moving one degree per second. You can follow that easily. But in the binoculars they're moving 15º per second! You'll NEVER follow that easily or for very long.

Now to resolve an arc-second it's not enough to have the 100x that makes the moon fill your field of view: that's only half a degree--1800 arc-seconds! You need at least 500x and more likely 750x for detail that small. This means on our sub in calm water, and object streaks across our field of view at 500 to 750 degrees per second. With your standard issue mark one eyeball 1x vision it would circle your head twice a second. Can you follow that up and down every five seconds and then measure two objects only one arc-second apart? No. Put a telescope on the roof of a building and try it. That tiny amount of movement makes it impossible to do there either.

Does tha arc-second have any relevance to navigation or targeting on a submarine? No. We work with whole degrees at best and error probabilities of several degrees. Error is part and parcel of our process and we're only successful if our procedures mitigate the unknown error in known quantities.

I just finished the remake of the Dick O'Kane Sonar Only Targeting technique on You Tube and it is a clinic on unavoidable error and how to render it harmless. Error mitigation, not any function of arc-seconds, is what allows us to be successful when we navigate and shoot our torpedoes. In fact, that video shows that in spite of errors that can total a couple of degrees, 7200 arc-seconds, you can put four of four torpedoes into a target you've never laid eyes on! So does one arc-second have anything to do with submarines? No.

[Crannogman]

Certainly the arc-second is too small a unit; the arc-minute, being closer to the actual resultion of the human eye, might be more useful.

In truth, any measurement standard made by man is bound to be an "arrogant" attempt to describe a fluid natural world by an inadequate standard. The usefulness of a measurement standard depends on its use. The Imperial system works well in measuring certain human-sized things, like base-paths and butter, but it flounders when measuring things like atoms or galaxies. Centimeters and meters may be unwieldy for measuring a human height, but you can also use decimeters (and you don't have to use two different units, as in 5-feet 10-inches).

Moreover, the measurement is only as good as its standard. The Imperial system failed to adapt to improving technologies that made measuring more precise, explaining part of why it has been superseded by the metric system. The speed of light is not constant under all conditions, but it is constant enough under the conditions set forth in the definition of the meter; in truth, even this has evolved from a speed-based measure to the wavelength of a very-defined color of light. A measurement system based on an object, as was the case for the Imperial system, can be thrown into chaos if the standard object is destroyed, as happened to the Imperial system. However, a system based on a constant, as is the metric system, can survive the destruction of the Earth itself, provided the information about the definition of the measure remains. Across the galaxy, a recipient of the knowledge can accurately reconstruct the correct system of weights & measures to pencil & paper the correct meight-based dose of Dopamine etc.

Until the day when our computer/robot overlords are running everything, there'll still be some schmuck trying do some weight-based dosing or the like in their head or by hand, and it's much easier when all your measures can be done in decimal system with interchangeable units. The hardest part now is dividing the stated weight inpounds into a more-usable mass in kilos.

As for the original poster's question, I haven't looked for a pressure measurement in the game; presumably it's in the Imperial system's pounds per square inch (PSI) if you select Imperial units. I haven't played in metric, only Imperial (since that's more historically accurate), so I can't be sure...

[LittleGrebe]

Originally Posted by Rockin Robbins

A meter is a measurement drawn up by arrogant Frenchmen, thinking that measuring things for the use of man should have their basis in measurements of dead things. Like the planet Earth. They carefully measured the circumference of the Earth, took a fraction of that and called it (ta da!!!!!) the meter. Made a platinum bar they put in some vault as the arbiter of the new unit. Imagine, people who liked to style themselves "humanists" dehumanizing the entire measurement system! Makes sense. To the ancient Greeks man was the measure of all things. To the French of the time man was only raw material for the guillotine.

...

Reading this post because I'm looking for more info about measuring distances in SH4. And suddenly I find myself in another dimension.

Brilliant text!

[getbac]

BEST THREAD EVER