Hi all

I was browsing MPI Outdoors, and came across a section that showed me how to find direction with an analogue watch, a skill which I know and have practised.

It also says that you must set your watch to Greenwich Mean Time when you do this. I was unaware of this. South African time differs by 1 hour, so either i am really inaccurate (possible), the technique isn't reliable, I misinterpreted the information, or the information is wrong.

Here is an extract from the section:

<< Take your analog watch (one with hands) not a digital, and reset the time to Greenwich Mean Time, that is Eastern Standard Time plus 5 hours. (NOTE: determine the number of hours difference from GMT in your area before using this method.) >>

Can anybody tell me if this is the correct method?the answer?

doesn't the last sentense says you have to use your own time, in a rather confusing way ?

i use the local time and it works just fine ( +1 hour from greenwich ). I think that doesn't really add up if you use GMT. On the norther hemisfire, the sun is always on the south wenn it's 12 a clock. If you put GMT on your watch and you are in the states or something, at 12 a'clock on your watch the sun will be on the east than ! ( well almost east ).

Thats the answer I was hoping for.

That doesn't make sense. I believe they are confusing finding true north (or south) with finding longitude.

To find your longitude (and without a sextant, calibrated chronometer, and almanac you could only get a rough estimate) you could determine when the sun was exactly due south (or north, if you're Australian <img src="images/graemlins/wink.gif" alt="" /> ) in GMT. So, for example, if the sun is due south at precisely 2:00 p.m. GMT, you would know your longitude is precisely 30 degrees West.

But this has nothing to do with finding direction. I think someone was relying on their memory and got the two techniques <img src="images/graemlins/confused.gif" alt="" />

I have used this technique before, and checked it against a compass to find what direction north is. I Have an idea about why it works, but it will be quite long winded. this is the link to MPI Outdoors

http://www.mpioutdoors.com/knowledge.htm

Scroll down the page a little bit. I originally got the technique from John Wisemans 'SAS Survival Manual'

BTW I am NOT Australian, thank your very much <img src="images/graemlins/blush.gif" alt="" />. I am a true, thoroughbred SOUTH AFRICA BOER!!! <img src="images/graemlins/grin.gif" alt="" />

LOL - we in the Northern Hemisphere always tend to think that Australians are the only ones who do things upside down <img src="images/graemlins/wink.gif" alt="" /> I'd forgotten you were a South African <img src="images/graemlins/blush.gif" alt="" /> (Guess I should have looked closer)

This description can't possibly be right. The time difference here between GMT and local time is 7 hours. According to this, I should set my watch so that it reads 12 noon when it's 5 a.m. local time. At 5 a.m. local time, the sun will be just rising - at my latitude, it will be southeast, at more southerly latitudes it will be closer to due east. But according to the MPI instructions, it will be due SOUTH.

They have the directions confused with another technique. You are right - your watch should be set to local time (indeed, for best accuracy, it should be local solar time, not local mean time).

You have to use your local time--and make sure you adjust for such nonsense as daylight savings time if you have such things down there.

It's actually a pretty accurate method, some compasses have a card printed on them to do the inverse calculation (i.e. get the current time given you know where north is from the compass)

Elnath

Do you have any details about that technique? Is it simple working backwards once you have your direction, or are there other factors to consider?

Nothing special,

At noon (local time) the sun is due south er sorry north for you <img src="images/graemlins/blush.gif" alt="" />. It moves 15 degrees per hour. So if the sun is at 345 it's 13:00, 330 it's 14:00, etc. Accuracy is as good as you can measure the angle. Quarter hour should be entirely doable (i.e. 3.25 degrees). A bit more difficult at night of course....

That's how sundials work, they are just fixed compass cards aimed due south (or north). (although on good ones the pointers are also set for a certain latitude as well to get optimum shadows).

thanks elnath. thats quite a clear description.