Navigation with a wristwatch?

Factual Questions
1

Help me out here guys - it just might save my life or might have given comfort if I had known the answer earlier.

I was backpacking in Namibia last year - southern hemisphere note - and got lost in the bush for a while stupidly without compass as “wasn’t going far” (almost famous last words). Anyway I recalled some boy scout stuff by which if you are without a compass you can figure out rought north by pointing the hour hand of your watch at the sun and then halfway between that and twelve is north (don’t ask what you do if it is six p.m. wait an hour I guess…).

Anyway when I suggested that solution it was pointed out to me that it might be the other way around in the southern hemisphere. We tried to work it out from first principles but failed and got our way home more through luck and a good memory for landscape than skill.

My question is does this methodology actually work and if it does what changes if anything in the southern hemisphere. If anyone can explain why it works that would be interested too but not essential.

Over to you straight dopers…

2

Actually, this procedure will help you find south in the northern hemisphere. But in the southern hemisphere, it’ll just get you lost unless you have a watch that runs counterclockwise.

In the temperate zones (between the tropics and the arctic areas) the noontime sun is always to the opposite of the hemisphere you’re in; i.e., the noon sun is always to the south in the northern hemisphere.

So at noon in the north, pointing the hour hand at the sun will point 12 at south.

At 3:00 pm, the sun will have an azimuth of about 225[sup]o[/sup]. Pointing the hour hand at the sun will have the 12 pointing at about an azimuth of 135[sup]o[/sup]. Halfway between the two is azimuth 180[sup]o[/sup] - due south.

At 6:00 pm, the sun will have an azimuth of 270[sup]o[/sup], 12 will be at 90[sup]o[/sup], halfway will be 180[sup]o[/sup] - south again.

But in the south, the sun acts slightly opposite of what us Northerners expect. Depending on how you look at it, it’ll seem to travel backwards from what we’re used to.

At 12 noon, the sun will be at due north.

But at say, 9:00 am, the sun will be at azimuth 45[sup]o[/sup], 12 at 135[sup]o[/sup], so halfway will be 90[sup]o[/sup] - due east.

At 3:00 pm, the sun will be at 315[sup]o[/sup], 12 at 225[sup]o[/sup], and halfway at 270[sup]o[/sup] - due west.

You’ll get lost real fast down under using the watch compass procedure

3

Unless you happen to be in Washington DC around the equinox, right? :smiley:

4

In the southern hemisphere, the way to do it is point the 12:00 mark on your watch to the sun. Halfway between 12 and the hour hand, is the north line.

The method does actually work, at least for general directions, as long as it’s not overcast. Daylight savings time can throw you off too.

If you really don’t want to get lost, invest in a good compass and take a land navigation course. Take a second compass as a backup. GPS is fine, but more people get lost with GPS than with compasses. People tend to forget that batteries can die out when you need em most, and the spare ones are always with the can opener and the soap. At home.

5

This is soooooo true. I’ve taught Scouts and adults before, and I can’t stess enough: GPS tells you where you are. A good compass will tell you how to get there. Of course, you have to understand the fudndamentals in order to use them correctly.

I would also recommend taking whatever maps you use down to a local printing shop, with a piece of Tyvek (the house-wrap stuff). Usually, they can print a copy in a non-water based ink (no smears, and rainproof), and the Tyvek is virtually tearproof. . . It’s sorta expensive, but I use mine all the time.

Tripler

6

Thanks guys - and I too totally recommend carrying a compass at all times and knowing how to use it. We couldn’t believe that both of us had left ours in camp and it certainly taught me a lesson I will not forget. Rest assured too I know how to navigate with one, just not previously too well without one. The wristwatch thing is just a useful fallback to know of to keep you in roughly the right direction - or at least not heading 180 degrees the other way!

As for GPS - yeah def not a good idea for backpacking etc. but they have their place. In southern African everyone into serious 4WD exploration/driving seemed to carry one - again except us!

Thanks for the advice - does the southern hemisphere methodology have universal support (just before I log it into my memory banks)? Surely if it was just something about needing a watch that went counterclockwise you could look at it for underneath whilst holding it above your head for one hemisphere and holding it at waist level and looking at it from above in the other, no?

7

notquitekarpov,
what I used to do is keep the backup compass in whatever jacket/vest that I usually where so that it’s always with me. Make it a habit. (I STILL carry a compass with me and I live in St. Louis)! Any of the cheap simple pocket watch types or the pin on ball types are perfect.

As far as the watch method working, I know it works in the north, and the south method was taught in the same survival class. If worse comes to worse, just use the old stick shadow method. Put stick in ground or just use the shadow of a branch of a tree, mark end of shadow. Wait a bit for shadow to move, mark end of shadow again. Draw a line between the points. The first point is west, the second point is east, no matter where you are.

8

In the northern hemisphere, you point the hour hand to the sun and halfway between that and 12 is south. In the southern hemisphere, you point the 12 to the sun, and halfway between that and the hour hand is north. Sort of reversed. (From http://www.adtdl.army.mil/cgi-bin/atdl.dll/tc/21-3/ch9.htm)

9

This wristwatch navigation method will even work in the southern hemisphere.

http://www.princetonwatches.com/shop/PAT2GP-1V.asp

http://www.gearreview.com/casiogps.asp