Watch As Compass..Please clarify

H

HLBennett

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Jan 4, 2000
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I've been reviewing some of the survival books in my library and have become confused with the directions for using a watch and the sun as a means of determining direction. Here is my confusion.

Say you are in the northern hemisphere. About every manual I have ever read says point the hour hand at the sun and North is located roughly halfway between the hour hand and 12:00.(Except of course during daylight savings time when you use 1:00)

OK, here's my dilemma. Which 12 0'clock gets used? In my way of thinking (as twisted as it is) if one points the hour hand at the sun at 0600 then north would be roughly in the direction of the number 3 (0300). However, if
one points the hour hand at the sun at 1800, north is now in the direction of the number 9. (180 degrees away from the number 3)

So which 12:00 gets used? Does north, in this case, lie between the hour hand and noon (1200) or between the hour hand and midnight (0000)?
Sure this is spitting hairs, however, most of the manuals I have read, seem unclear.
 
The method I have always used is to point the hour hand at the sun, and due SOUTH is half way between the hour hand and 12:00.

If you have a sundial, you need a compass to orient it in the proper direction to tell time. If you have a watch you know what time it is and work backwards. Basically what you are doing is making a sundial, and using it in reverse.

There are navigational tables that will tell you exactly how much declination to allow depending on the date and your general location, much like correcting for magnetic north with a compass.

Without the specific charts accuracy is fair, maybe within 15 degrees one way or the other.

Before the days of Global Positioning Satellites "Sun Compasses" were fairly common equipment for explorers especially in areas with strong magnetic fields or near the north and south poles where a magnetic compass gives erratic results.


Mike


As an after thought. let me take another shot at answering your question. If the time is before noon you move clockwise, forward half way toward 12:00 to show south. If the time is after noon you go back counter clockwise half way toward 12:00 to show south.

I quess that moving in the bach in the morning and forward in the afternoon would give you north rather than south, but I have always used south with a watch.

You can even use a knife blade held upright at the edge of the watch to cast a shadow back over the hour hand to the center of the watch to help align the watch.
smile.gif



MNH

[This message has been edited by MNH (edited 04-05-2000).]
 
I read somewhere that the watch method is a really rough estimate. It can be off by 20 degrees, if I remember right.
You might try searching the site, because there was a really good thread a few months ago posted by Greg Davenport.
 
I think this is also covered in FM 21-76, but Greg's is a better description.

Mike

[This message has been edited by Michael Bennett (edited 04-05-2000).]
 
Originally posted by HLBennett:
About every manual I have ever read says point the hour hand at the sun and North is located roughly halfway between the hour hand and 12:00.
Click to expand...
I prefer to keep the clock face "stationary" and put the sun between 12 and the hour hand.

Or even better, having a watch with a 24h hand.



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It's in volume 4 "navigation" video.

Place a thin stick over the center of the dial. Cast a shadow down the hour hand. Half way between the hour hand and 12 is North standard time and halfway between the hour hand and one is North in daylight savings time. Accuracy depends on many variables including levelling of the watch face, angle of the stick, time of year, latitude etc. etc.

It gives you general direction for general navigation in case you get "turned around".

You can use it to determine a rough "North" during the day time, point a stick in that direction and that night use the stick to point where you should be able to locate the big dipper etc to find Polaris (North Star) Now you can get latitude, direction etc. very accurately. You can also then tell magnetic declination. In the video.

Ron



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It is easy to determine which direction to use if you remember the cardinal points of the compass.

North is always to the left or counter clockwise from East, so in the morning you move in the counterclockwise direction towards 12 find North.
North is always to the right or clockwise from West, so in the afternoon you move towards the 12 in a clockwise direction.

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It is easy to determine which direction to use if you remember the cardinal points of the compass.

North is always to the left or counter clockwise from East, so in the morning you move in the counterclockwise direction towards 12 find North.
North is always to the right or clockwise from West, so in the afternoon you move towards the 12 in a clockwise direction.

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Thanks for all the replies.

Doug, your description was very helpful for the method I was previously using. Thanks.

Doc Ron,

I reviewed my copy of WM IV. After careful review, and seeing the method demonstrated along with the Shadow stick method and Omani sun compass, I realized my error in thinking.
Thanks.
 
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