Citizen Navihawk/Skyhawk: How to Use the Slide Rule Bezel

This video shows you how to do simple calculations including rate/time/distance on the slide rule bezel of a pilot's watch. The watch shown in the video is the Japan-only Citizen Navihawk 2000GT. In this country it's known as the Skyhawk.

Category:

Science & Technology

Tags:

• citizen
• navihawk
• 2000
• skyhawk
• pilot's
• watch
• pilot
• slide
• rule
• sliderule
• bezel
• wristwatch

[schitlipz]

Inaccurate to say the least. My God, 3*3 is a tad greater than 9. And the manual has some bad translation on finding roots (very bad translation).

I've got a titanium btw.

In any case, do you know if roots can be found using this exact similar bezel or is it a page they should have left out of the manual? Thanks in advance, bro.

Wow. In one week I've found half dozen ways this watch could be better.

[nikudes]

@schitlipz Yes there is a way to find roots. It's sort of like doing a division problem. To divide 20 by 40 for example, you'd move 20 on the outer bezel ring opposite 40 on the inner ring and read the answer opposite 10 on the inner ring: 50 (meaning 0.5 because you have to figure the decimals out on your own). But you want the square root, meaning the condition in which both multipliers are equal.

[nikudes]

@nikudes So to find the root of 20 turn the bezel until the number opposite 20 on the outer ring, and opposite 10 on the inner ring, are the same. In this case that's about 45 (meaning 4.5). The square of 20 is actually about 4.47.

[negolatak]

This is a very good video but I don't understand what you mean by "point of origin" when you're talking about division and multiplication?? Please explain?

[nikudes]

@negolatak I refer to the number 10 on the inner ring as the "point of origin" because that's where one starts counting numbers. It's the equivalent of zero. It just means that if you divide any number on the outer ring by the one underneath it on the inner ring, you can find your answer on the outer ring opposite the point of origin (which is the number 10 on the inner ring). Does that make sense?

[negolatak]

@nikudes Yeah, I finally understood that a little while later, but thank you anyway. I wonder why there's no "0" as point of origin though, why it would start on 10 and not on 0?

[nikudes]

@negolatak I'm not sure. Slide rules usually start on 1. you could think of 10 as 1.0 and 11 as 1.1 because the decimal point depends on how you define the numbers. But why no zero? I don't know. You'll have to ask someone better at math than I am.

[UpsideDownInfo]

Thank you for uploading this video

[07350z]

very informative video, thanks for posting

[schitlipz]

@schitlipz ... (316) instead of 10 you can find that other root value. This is a curious thing I've never noticed in any math class.

Does anybody know why there are two roots depending on decimal place? It's not as simple as "even roots having two values". It must have something to do with the numerical base... perhaps. Ideas?

[schitlipz]

@nikudes Yeah, I was messing around with the root thing and figured the "fine-tuning" thing. It's not particularly helpful because because finding two similar numbers at different parts on the bezel isn't a quick operation. Also, more importantly, square roots (or third, fourth, etc) have two values depending on the decimal position. Example: root of 7 and 700 are numerically the same, 70 and 7000 too, though different. I'm not sure why, but if you read the value at root 10 ie 3.16