Forum: Just Getting Started In Geocaching
Topic: GPS Coordinates vs. compass heading
started by: Moose

Posted by Moose on Oct. 19 2003,12:58 pm
In many of the posts that I've read, experienced cachers say that when they are close to the site (50'-100'), they turn off their GPS and use a compass.  This is probably a dumb question, but how do you convert the GPS coordinates into a compass direction? ???
Posted by Scout on Oct. 19 2003,3:45 pm
Quote (Moose @ Oct. 19 2003,1:58 pm)
In many of the posts that I've read, experienced cachers say that when they are close to the site (50'-100'), they turn off their GPS and use a compass.  This is probably a dumb question, but how do you convert the GPS coordinates into a compass direction?

I think what they do is take the last compass heading their GPS gives them, then use that with their compass. I doubt they are doing mental calculations to convert lat/lon into compass directions. I think the real key to their success is that they quit looking at an instrument in their hands and start looking closely at their surroundings, trying to guess where a geocacher would hide a cache. That's what actually gets you to the actual hiding spot, not your GPS or a compass.



Posted by PC Medic on Oct. 19 2003,5:28 pm
I agree with Scout.

Generally what I will do is use the compass heading on my GPS (along with a topo map when needed) while watching the distance also. As soon as it gets down to around 30 feet I will generally place the GPS back in its holster and using the clues play the "now where would I hide it" game. Keep in mind that depending on satelite lock I may be further or closer when switching over. If you reach a point where the numbers (distance) starts jumping around eratically, it is time to start scanning the area by eye.

Posted by 4x4van on Nov. 04 2003,11:22 am
Yes, there have been a number of times that I couldn't quite "zero in" on the cache untill I backed away 20-30 feet, looked at the compass arrow on my GPS, and then walked that direction while ignoring any further info from the GPS.  As said, at that point you must start to think like a geocacher, i.e. "where is a good hiding location around here?".

Also, remember is this:  If you are going to use the "bearing" given by your GPS with a handheld compass, make sure your GPS is set to "Magnetic North", not "True North", or the bearing will be off.

Posted by hackie on Nov. 17 2003,8:01 am
I think it depends on the location of the cache whether to use the "old-fashioned" compass or not. Especially when tree covers or narrow ravines do reduce the GPS signal's field strength, a compass may become helpful.
Personally, I try two locations around 100 m afar from the cache to get a bearing. On a map it is a sort of triangulation.
And with no obstructions in your way of bearing, you may reach the cache's location within a 5 or 10m range.
There, of course, it comes down to your cunning to spot the likely cache places.

As already mentioned, check your GPS to be set to "Magnetic North".  :thumbs-up  

Greetings from Hackie

Posted by strikeforce_sunset on April 25 2004,12:16 pm
I run a garmin 12, and when I get to .02 away from my target the gps doesn't give me a bearing anymore. Therefore, as I approach, .03 away, I breakout my compass and set the bearing I need to get to the target. It works every time. There are some times the geo gods play havoc with the satalites, or magnet fields scramble the gps. I back off my target to .03, take a bearing, create a circle at that distant and take a few more angled bearings. It never has failed me, I call it - triangulation , I find my target a lot quicke than some others with the higher end gpsr the go down to feet. So in short, I use a compass all the time.  :)
Posted by duke on April 28 2004,6:37 am
Quote (strikeforce_sunset @ April 25 2004,1:16 pm)
I run a garmin 12, and when I get to .02 away from my target the gps doesn't give me a bearing anymore. Therefore, as I approach, .03 away, I breakout my compass and set the bearing I need to get to the target. It works every time. There are some times the geo gods play havoc with the satalites, or magnet fields scramble the gps. I back off my target to .03, take a bearing, create a circle at that distant and take a few more angled bearings. It never has failed me, I call it - triangulation , I find my target a lot quicke than some others with the higher end gpsr the go down to feet. So in short, I use a compass all the time.  :)

??? I assume .02 means miles?
Posted by virgo91967 on Sep. 04 2004,10:02 pm
well, My maggie 310 usually begins to loose its bearings at anything less than .01miles( roughly  500-528 feet) just because it is from the SA age.  what I have learned to do is first do all my caching as possible with UTM coordinates.. Automatically gives me a 'BEST DAY' accuracy of 1 meter (3.25 feet).  but not all of us have best days :p

When I get to within 53 feet (.01mi.) or 10meters (.01 Km or roughly 40 feet) THEN I break out the sheet with the cache's UTM coords on it, flip the display to current coordinates and either start thinking like a cacher (80%) OR begin to match the numbers (20%).  If the my caching 'mojo' doesnt come up with a most likely place, then I start matching coords.  I usually start by flipping my display over to navigation mode where it shows my current coords, then I start walking until the difference between where I AM and where I am SUPPOSED to be reach zero.  there have been many times that I have found myself within feet of the cache.  once sat my GPSr right next to it, not knowing.  

IMESHO:  anyone who pays attention to the time of day and the positon of the sun when they go out should be able to remeber which way is north well enough to get them back to where they need to be provided they maintain a clear head and think it through.  
If you are trying it at night... best to wait till daybreak :rollwink:

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