Watch Compass

[bushcraftbob]

Was watching a repeat of Bear Grylls the other night (the Everglades one) - he used his watch as a compass, by pointing the hour hand at the sun and then finding the middle point between the hour hand and the 12 hour on the watch, which points south...make sense? does this actually work?

 

[John Fenna]

Yes it does!
Something that Teddy Bear is not faking!

 

[h2o]

yes it works .you can even do it with a digital watch and a bit of imagination.

 

[pothunter]

It wasn't a digital watch was it? or am I just being even more cynical.......

 

[illumeo]

I can't remember, i think you have to make an allowance for daylight savings time if your watch is set to it (ie your watch has to be on local time, which is close to the local solar time). I am sure someone here will know. Any way in summer in the UK if your watch is on BST knock an hour off (i think)

 

[spamel]

Yes, it works that way if you are in the northern hemisphere. In the southern hemisphere, you point 12 o'clock at the sun and bisect between 12 and the hour hand. Halfway is north.

 

[pothunter]

Alternatively, buy a compass

 

[BorderReiver]

Was watching a repeat of Bear Grylls the other night (the Everglades one) - he used his watch as a compass, by pointing the hour hand at the sun and then finding the middle point between the hour hand and the 12 hour on the watch, which points south...make sense? does this actually work?

It works well,even with a digital if you can remember what a watch face looks like.

Take your watch and your compass outside and try it.

 

[Tiley]

It really does work and is reasonably accurate - certainly accurate enough to get out of trouble or settle squabbles about which way is north. There used to be a really expensive solution to the problem made by IWC in the 70s and 80s: a mechanical watch with a compass underneath. It was incredibly pricey because the watch movement had to be made from gold so as not to affect the compass needle. Daft but entertaining.

 

[spamel]

I believe the germans had something similar during world war 2.

 

[Greg]

Alternatively you could get yourself a digital compass watch! Like my Casio Pro Trek.

 

[illumeo]

needle, cork and bowl of water, a la the "empire of the sun"?

 

[h2o]

There is also a firm called silva that make the ideal gadget for direction finding

 

[Stuart]

Whilst the watch compass method is a general indicator of direction, its accuracy is greatly overstated in the majority of survival texts.

The famous navigator Harold Gatty said of it "it is a great pity to destroy illusions, but in the case of the watch method it is necessary to do so because the apparent simplicity of the method may give a very wrong impression as to its accuracy"

It’s commonly around 30 degrees out, but at the lower latitudes it is possible for this method to be as much as 175 degrees off, that’s almost completely the opposite direction! Even in Europe it can sometimes be as much as 70 degrees out.

It used to be known as 'the Eskimo watch method', because for obvious reasons the one place this method does become feasibly accurate for navigation is within the polar circles.


the reason for this inaccuracy it the assumption that the sun changes its azimuth as a constant 15 degrees per hour (which it doesn’t), the methods inherent error is compounded by the fact that most texts fail to mention that the watch should to be set to solar time and even those texts that do state this, fail to inform the reader how to make such an adjustment, which requires that they know their longitude, the equation of time, the time zone their watch is set to and any daylight savings adjustments that it was using.

In short is a very rough direction indicator

 

[andy_e]

Here's a question, would the same trick work on or near the equator?

Edit: Stuart, I think you just answered my question while I was typing it, thanks.

 

[pothunter]

So its more accurate to wait for birds to fly south for the winter.

Stuart, if I were to try this method taking a bearing every hour would that result in me walking in an arc? or would it create a sine wave over the course of a day, mid day being the turning point of the sine wave, this must also link into tidal flow. Gettin a bit out of my depth here.

Pothunter.

 

[Moff8]

after looking out of the office window here in 'sunny' Glasgow - is there a method of locating the sun using a watch

 

[andy_e]

after looking out of the office window here in 'sunny' Glasgow - is there a method of locating the sun using a watch

Well I think we're due some sun about half-past May?

 

[Stuart]

Stuart, if I were to try this method taking a bearing every hour would that result in me walking in an arc? or would it create a sine wave over the course of a day, mid day being the turning point of the sine wave.

An asymetric arc I think, looking at the data I have here it appears that even if you walked at a constant speed for the exact same number of hours after noon as you did before, you would still not end up on your intended bearing. as the end of the latter leg of the arc is quite a bit higher (for the date and co-ords that I am looking at, somwhere in Texas on june 22nd) than that of the start.

 

[fishfish]

ive used the method to set a sundial!