Using your watch as a compass

General cycling advice ( NOT technical ! )
Carlton green
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Re: Using your watch as a compass

Postby Carlton green » 1 Aug 2020, 2:20pm

Cowsham wrote:
Carlton green wrote:
Cowsham wrote:Don't forget that a dog can smell better than you can see.


I did wonder about that, him picking up a sent from where we had already been. However on the outward leg I let him roam in front and he picked suitable trails that ended up in an area we had a little familiarity with.


To us it's probably like having long distance xray vision. A superpower a doge takes for granted.


Thread drift. Superpowers ... my JRT could size someone up from 100 yards, decide who had biscuits in their pockets (or any other food) and then literally charm his ‘victim’ into feeding a poor hungry and deserving Doggy. Initially I was embarrassed but overtime I just laughed and admired his skill ... oh well, suppose we better get back to direction finders.

Jdsk
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Re: Using your watch as a compass

Postby Jdsk » 1 Aug 2020, 2:26pm

thirdcrank wrote:Thinks: why orientation? Why not a word like borealisation?

I'd guess that the dual meaning got locked in to French when maps had E at the top.

And before the magnetic compass was widely known.

Jonathan

Jdsk
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Re: Using your watch as a compass

Postby Jdsk » 1 Aug 2020, 2:28pm

Carlton green wrote:Superpowers ... my JRT could size someone up from 100 yards, decide who had biscuits in their pockets (or any other food) and then literally charm his ‘victim’ into feeding a poor hungry and deserving Doggy. Initially I was embarrassed but overtime I just laughed and admired his skill ... oh well, suppose we better get back to direction finders.

To avoid the Clever Hans effect I'd like to see that run double blinded.

Jonathan

Tangled Metal
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Re: Using your watch as a compass

Postby Tangled Metal » 1 Aug 2020, 2:58pm

Our dog is a border terrier which has a reputation for navigation by smell. For example if they run off and lose their owner I've been advised that they tend to follow they're scent back to where they left you and then follow your scent to find you.

A good example of this was in a campsite where it went wild when a young boy had chased a rabbit around a wide bush and tree before the rabbit darted across our path closely followed by our dog and me holding onto the lead.

Well rabbit got away and dog went back to the path then caught the rabbit scent again. It then followed it around the tree then right back across to where it had only just chased the rabbit off to.

Orientation of dogs? Don't need orientation when scent is detectable for hours plus after you've passed a place. They're better at retracing steps than orientating themselves.

Orientation of humans? Not all humans are the same in that respect? Both me and my dad have an instinctive feel for direction. Even in new areas I really check the map for confirmation a lot of the time. I judge paths by their orientation as to whether they're right.

nosmarbaj
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Location: Reading

Re: Using your watch as a compass

Postby nosmarbaj » 1 Aug 2020, 3:27pm

You can of course also use a compass as a watch. I was backpacking for a few days in the Scottish Highlands once and found I'd accidentally stopped my watch. From the direction of the sun I had a fair idea of the time, but just for fun I corrected for my position W of Greenwich, and also for the deviation of magnetic N from true N (as given on OS maps). I then set my watch to the calculated time. On my return to civilzation, I found I was less than 2 minutes out. (I don't claim I could do it as accurately every time!)

Jdsk
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Re: Using your watch as a compass

Postby Jdsk » 1 Aug 2020, 4:03pm

Excellent.

Jonathan

Cowsham
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Re: Using your watch as a compass

Postby Cowsham » 1 Aug 2020, 10:40pm

nosmarbaj wrote:You can of course also use a compass as a watch. I was backpacking for a few days in the Scottish Highlands once and found I'd accidentally stopped my watch. From the direction of the sun I had a fair idea of the time, but just for fun I corrected for my position W of Greenwich, and also for the deviation of magnetic N from true N (as given on OS maps). I then set my watch to the calculated time. On my return to civilzation, I found I was less than 2 minutes out. (I don't claim I could do it as accurately every time!)


Was that like finding direction using your watch only in reverse?

nosmarbaj
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Re: Using your watch as a compass

Postby nosmarbaj » 1 Aug 2020, 11:44pm

Cowsham wrote:
nosmarbaj wrote:You can of course also use a compass as a watch. ...


Was that like finding direction using your watch only in reverse?

Basically, yes. In the northern hemisphere the sun is due N at midnight (true N, not magnetic N - and of course the sun will be below the horizon in British latitudes), and moves clockwise by 15 degrees per hour, so is due E at 06:00, due S at 12:00, and due W at 18:00. So you can work out the solar time by the direction of the sun as shown by the compass, and correcting for the fact that magnetic N is not the same as true N (the deviation may or may not be significant depending on your location; it also changes over the years as the magnetic pole's position drifts.) To get clock time from solar time you need to know your longitude in relation to the standard time for the region you are in. In the UK, for each 1 degree W of the Greenwich meridian, you need to add 4 minutes to the solar time. Finally, if relevant, add an hour for Summer Time.

ETA - this of course is simply how a sundial works, but as it's in a fixed location, the directions are known and you don't need the compass.

simonhill
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Re: Using your watch as a compass

Postby simonhill » 2 Aug 2020, 10:42am

Jdsk wrote:Yes, you point the noon mark on the face of the watch towards the sun, and bisect the angle to the hour hand.

But it's the noon mark that you need to use in both cases... that isn't always twelve.

And it's much more complicated if you're in the tropics.

Jonathan


Maybe I've misunderstood, but I just tried it and it didn't work. Bisecting the angle between hour hand and midday gave me a line more E-W than N-S. (Field in Essex, 10am BST. Sun was SEish, making 9 hour hand (GMT) NEish. Bisect that and it is E-W.)

Please correct me if I am wrong.

Sundial method was spot on.

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simonineaston
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Re: Using your watch as a compass

Postby simonineaston » 2 Aug 2020, 10:46am

You're not using a digital watch are you... ? :wink:
ttfn, Simon in Easton
(currently enjoying a Moulton TSR & a nano Brompton...)

Jdsk
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Re: Using your watch as a compass

Postby Jdsk » 2 Aug 2020, 11:14am

simonhill wrote:Bisecting the angle between hour hand and midday gave me a line more E-W than N-S. (Field in Essex, 10am BST. Sun was SEish, making 9 hour hand (GMT) NEish. Bisect that and it is E-W.

The sun was SEish, and you point the hour hand there with the watch face horizontal. Your time of observation was 10 o'clock so you've now got 10 on the watch face pointing at the sun.

Local noon is currently about 1 o'clock.

Bisecting that angle of 90° between 10 on the watch face and 1 on the watch face gives you south, at half past eleven on the watch face.

Jonathan

thirdcrank
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Re: Using your watch as a compass

Postby thirdcrank » 2 Aug 2020, 11:59am

This is all fascinating and it reminds me of some informative stuff from my long-gone childhood about how to do really useful things.

In the context of cycling, I cannot help thinking that any benefit from being able to tell the time by watching which way the crows are flying is likely to make you late.

Anybody wanting to perform mental PE to keep the grey matter active might do worse than work out gear ratios and then distanced travelled counting pedal turns. You might even arrive early.

Nigel
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Re: Using your watch as a compass

Postby Nigel » 2 Aug 2020, 12:12pm

To add to the thread, there are also talks and a few books from Tristan Gooley, his most famous being the Natural Navigator.
Having heard him interviewed on the radio a few months back, he seemed reasonably sane.

The string and let-go, then turn to north method seems a good one, particularly as I wear an old-style Casio digital when riding.

- Nigel

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The utility cyclist
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Re: Using your watch as a compass

Postby The utility cyclist » 2 Aug 2020, 1:49pm

Mike_Ayling wrote:My Garmin Etrex 30 has a compass function but I have never tried to use it

Mike

I've used the compass/angle bearing on my old Megallan Meridian to set the angle of a TV aerial, worked bob on :D. In terms of on the bike, the only time I actually used it was when we were exploring some back lanes in France about 12 years ago to make sure we were heading in right direction of a fork junction as wasn't 100% sure, it wouldn't have actually made that much of a deal as both roads connected to the main road but one end was 3 miles in the wrong direction.
The Magellan It was a large bit of kit to be atop the bars of a 1950s Carlton but was a good backup and register of our actual route/miles done, I have one on the newer GPS but I'm finding I use them very sporadically.

nirakaro
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Re: Using your watch as a compass

Postby nirakaro » 2 Aug 2020, 2:01pm

simonhill wrote:
Jdsk wrote:Yes, you point the noon mark on the face of the watch towards the sun, and bisect the angle to the hour hand.

But it's the noon mark that you need to use in both cases... that isn't always twelve.

And it's much more complicated if you're in the tropics.

Jonathan


Maybe I've misunderstood, but I just tried it and it didn't work.Please correct me if I am wrong.

That's because you were following the wrong instructions! Jdsk was responding to my OP enquiry about how to do this in the southern hemisphere. The OP tells you how to do it in Essex.