UKC

I've just been cross referencing a place on Google Earth and MemoryMap using Latitude and Longitude(Position readout on Google Earth 42.919N; 0.187W). When I entered those co-ordinates into Memory Map it was over a mile out.

I managed to check the co-ordinates on Viewranger and the VR position tallied with the Google Earth position so MemoryMap looks to be incorrect.

Has anyone else encountered anything similar? If anyone has MemoryMap and is able to see what comes up I'd be interested

Thanks

were you using OSBG36 or WGS 84 on Memory Map?

Straight forward Lat and Long. I've just done the same on the MemoryMap for Snowdonia and there appears to be no discrepancy

Coordinates need a datum and geoid to mean anything. WGS84 and OSGB are different datum and geoid, so you need to know which you are using. Google probably uses WGS84 (as per GPS). Viewranger with OS mapping probably uses OSGB36.

Google and View Ranger were both giving the same result. It was Memory Map that was wrong, although it returned a correct result when I "tested it on another  Memorymap(Snowdonia)

Have you checked which datum & geoid it's using? It's usually a setting.

When I select(on MemoryMap) Position Mode as WGS84 it does not seem to allow standard Lat and Long format

The format for WGS84 displays something such as "30N 730265E 4757297N". I cannot see how that relates to Lat and Long

30N is the UTM zone. That suggests it is set for UTM, not OSGB36. The Easting and Northing values are metres within the UTM zone.

UTM breaks the earth up into a grid of zones, and applies a local projection to each zone, to minimise projected distortion for each zone (cf grid divergence in OSGB area). The lat/long coordinates in one zone will project to a different point in another zone. That's why it's prefixed with the Zone. The OSGB grid is like one of those UTM zones, but chosen especially for the UK.

https://en.wikipedia.org/wiki/Universal_Transverse_Mercator_coordinate_syst...

Thanks for you feefback and info. I've since tried it at an entirely different location on the same map and there is no discrepancy. For some reason or other it was only occurring in that original location. Thread put to bed now.

The difference between datums varies depending on where you are in the world. Around here WGS84 puts you about 180m NW of the same position in ED50 (or vice versa, I can't remember).  So it is entirely possible you are on different datums and they match at your alternative location.  Having spent hours out on my boat trying to find shipwrecks with position numbers given to me in unknown datum I've learnt to input the position with my plotter set to WGS84, then again at ED50 and search both locations. For a given location, setting the datum to WGS84 then a.n.other datum will give two different sets of lats&longs. WGS84 is the modern standard so I always use that.  With reference to the position you wrote out for us, not only are there different datums, but also different grids. You have 'OS grid' selected in your options rather than lat&long. I've not used Memorymap, but my garmin GPSes have options like OS grid, loads of other national grids then lat&long in multiple formats - degrees-minutes-secs-decimal secs; degrees-decimal degrees etc. I always use degrees-minutes-decimal minutes (thousandths) in the boat to get a position like 49-56-405 2-27-959