LAT.- LONG. to UK GRID REF'S - CONVERSION

[gansonwheels]

Folks, I am probably a bit dim about this and it is no doubt in the GC website somewhere or in my gps, but is there a method of converting Latitude - Longitude references, eg in multi-cache clues, into UK Grid References ?

I tend to have my gps left on Grid Ref's because I use it for walking as well as caching and it is a bind to switch it from one function to the other.

 

Cheers

Ganso

[+NickandAliandEliza]

Here is a website that does it. There are loads of others inc sites where you can download applications to do it with a PDA.

 

I've got a 60CSx and it's easy to flick back and forth between the grid ref's. When my eTrex Vista was working ( it's now out of warranty and Garmin wanted to charge me £51 to put it right) I used to keep that on the British Grid and the 60 on Long / Lat.

[+Amberel]

Folks, I am probably a bit dim about this and it is no doubt in the GC website somewhere or in my gps, but is there a method of converting Latitude - Longitude references, eg in multi-cache clues, into UK Grid References ?

I tend to have my gps left on Grid Ref's because I use it for walking as well as caching and it is a bind to switch it from one function to the other.

Do you have a PDA (PocketPC)? I've written a program that converts to and from WGS84 lat/long, OSGB lat/long and OS grid references, and projects waypoints and also reads an attached NMEA GPSr to give bearing and distance to a waypoint. It is a simple text application (no graphics) but is compact and works well enough.

 

Shout if you want a copy.

 

Rgds, Andy

[+flipflopnick]

OS have a spreadsheet on their site. http://benchmarks.ordnancesurvey.co.uk/

In Quest provide a Windows batch convertor. Spreadsheet of use in the field if you have PocketPC or Palm PDA.

 

In the field easiest to use your GPSr.

 

There are several PocketPC and Palm free programs to convert.

 

Be aware each method that converts OS to Lat Lon will give different results. They all use slightly different algorithm. OS grid ref describes a square, not a point. Lat Lon varies depending on Moon's distortion of Earth's surface. But for caching we only need to get within a few feet. So good enough.

 

Each coord system uses a different datum. More errors. OS used OSGB36. Groundspeak use WGS84. Your GPSr will preselect correct datum and do the conversion for you in the field. NB Memory-map in UK use WGS84 throughout, leading to erroneous coords when converting between OS and Lat Lon

 

So with multi, which datum has the setter used with which coord system? More apprehension.

 

In the field with a multi, change the settings in your GPSr, if you can remember how from Lat Lon to OS and back. Takes seconds if you can recollect. Take a crib sheet with you.

 

Why? Try finding a disused OS rivet using coords with an archaic different datum. It may or may not be there. Oh its 2 cm wide and dark coloured. Probably no one has visited it in 30 years. The surveyor's notes are like a Hint except in text speak.

[Edgemaster]

www.nearby.org.uk is awesome for conversions

[+The_Street_Searchers]

Is one more accurate than the other? I have a Garmin E-Trex.

 

Thanks

 

[+Bear and Ragged]

Is one more accurate than the other? I have a Garmin E-Trex.

 

Thanks

 

What, the conversion tables/programmes or Lat Long vs OS grid?

 

Probably Lat Long on the caching site, it's what most cachers use...

[+Amberel]

Is one more accurate than the other? I have a Garmin E-Trex.

 

What, the conversion tables/programmes or Lat Long vs OS grid?

 

Probably Lat Long on the caching site, it's what most cachers use...

WGS84 Lat/Long is the obvious prime location reference (well ECEF co-ordinates might be better but few will have access to those!)

 

The OS grid ref conversion on Groundspeak is a bit of a joke - it's the least accurate of any I've seen. Typically it is 6 or 7 metres out. The obvious reference for this conversion is the convertor on the OS web site. My own PDA program uses the algorithm supplied by the OS and gives the same results.

 

Rgds, Andy