Garmin eTrex settings for UK geocaching

[+forcesofnature]

I've recently started geocaching with my yellow Garmin eTrex here in the UK. I've found about 5 caches now but whenever I'm at the cache locality my eTrex is telling me I still have around 90m (300 feet) to go.

 

I'm assuming I have something set up incorrectly, can someone tell me what settings I should be using on my Garmin eTrex... In particular the Settins on the 'UNITS' page.

 

Thanks.

Alan.

[+Nellies Knackers]

as long as you have coordinates set to d m.m and datum to wgs84 (the datum is where most go wrong) you should be fine.

[+forcesofnature]

Brilliant, I had the Datum set to Ord Survey GB.... Shall have to go out and try again now.

 

Thanks for your help, and sorry to be such a newbie, but I guess that's what these forums are for.

 

Al.

[+forcesofnature]

Actually, I've just been out to try it with the datum set to WGS84. I went back to a ache I did earlier today and when stood right on top of it, the eTrex was once again telling me I had 92.5m to go, despite the fact that on the 'Ready to navigate' page it was stating an accuracy of 6m.

 

It looks as though my GPS unit is misaligned by 90m somehow?? Does anyone have any ideas??

 

Thanks.

Al.

[+Nellies Knackers]

It might be that because you entered it originally with the datum wrong it adjusted the coords again when you changed datum, I've had this happen before on a mixed datum cache.

[+forcesofnature]

Aha... That makes sense... I've just checked the coordinates entered for that cache and you are right, they changed when i changed the datum setting.

 

Thanks.

Al.

[+Jackplug]

In the settings/units page just hit default all at the bottom and you will be sure you have it set up right.

Kevin

[Dangate]

I'm a bit new to this, but I thought in British Isles the idea is to use British Grid for Position Format and OSGB for map datum. Use metric units for measurement and this should all tie up nicely with OS maps. Used mine today like that for 4 caches - all good.

[+forcesofnature]

Dangate... That is the settings I had my GPSr set on and I was 90-100m out on every single cahce I did.

 

Al.

[+dino-irl]

That would make sense if you were using it for walking in conjunction with a paper map. However, GC.com has elected to use Lat/Long in the d m.m format and WGS84 as the datum.

 

If you don't use the same settings as the setter then you're not going to get too close to the cache.

 

Well done to forcesofnature for finding so many with the wrong settings though

[barryhunter]

This page (probably still too rough to be called finished) might or might not help:

 

http://www.nearby.org.uk/gps_ll_v_gr.html

[+forcesofnature]

 

Well done to forcesofnature for finding so many with the wrong settings though

 

LOL... Thanks. I did choose ones in locations that I knew farily well and did have to use the additional hints to find them though. They were also all pretty easy locations, but now that I have my GPSr set up properlythere'll be no stopping me... Apart of course from family commitments, work etc etc....

 

Al.

[Dangate]

barryhunter - thanks that page was useful.

dino_irl - I see what you mean. I am a long time map and compass user (supplemented by gps last week), so I tend to think in Grid references. You live and learn - but I guess I'll stay with my old ways provided I can get cache data in that format.

Regards.

[Dangate]

Ooops! Sorry for yet another post. I've just re read what I said, and gone to look at listings of caches. I see now that the deg/min data for caches is in bold, and grid ref in faint. This implies, and dino_irl has told me, that deg/min is the principle format to be used in Geocaching. So if ever I want to move on to placing caches, that is what I should use.

Didn't mean to sound like I know best.

I'll get me coat.

[barryhunter]

I am a long time map and compass user

 

ditto!

 

but I guess I'll stay with my old ways provided I can get cache data in that format

 

if you haven't already checkout http://stats.geocacheuk.com as that's a UK based portal to geocaching, which makes searching using Grid References easier (postcodes/placenames etc), it also will display all coordinates quoted on a page as Grid Reference. [Created by a UK cachers that also likes Grid References!]

 

[Edit: just seen the second post... yes its true if want to place caches or work with many puzzle caches then lat/long is required]

Edited September 25, 2006 by barryhunter

[Edgemaster]

I was browsing around the OS datum information pages (which also go over all the messy conversion procedures) and came across a rather nice representation of the error:

 

Myth 1: ‘A point on the ground has a unique latitude and longitude’

Nope, as the example shows. (All the points are of the same latitude/longitude, bbut using different datums)

 

As a side note, the Ordnance Survey Datum can be represented as latitude and longitude, to make matters more confusing!

 

Edit: I should probably also note that I often change from WGS84 to OS Grid Refs while caching to get my place on a map. Just dont leave it on that setting when transferring waypoints.

Edited September 25, 2006 by Edgemaster

[+forcesofnature]

Just a quick note to say I went back to a cache today with my new datum settings and it was spot on....

 

Cheers.

Al.