I have 1:50k and 1:25k maps of the same area, but they don’t quite ‘line-up’ – i.e. if I draw a route along a, say, bridleway on the 1:25k and the scale out to the 1:50k, the route’s no longer on the bridleway its slightly off to one side. Same if I do it the other way round.

Any ideas? I assume it’s something to do with the datum in the maps.

It’s possible to get a shift if you use the wrong geodetic system, but both the 1:50 and 1:25 map should use the same if they are both OS:

http://en.wikipedia.org/wiki/OSGB36

Common problem. You can see the same if you draw a route along a 1:50k map and then “zoom out” to 1:250k on Anquet

PIA that. Shouldn’t happen but does, all the time. All maps, at whatever scale are supposed to be drawn from the same database

Same thing happens on TrackLogs. Pretty sure it’s down to the OS data, not the software.

I’ve got a route for Stanage Edge that runs parallel to the path on the ground. Following the GPS route precisely would have me over the edge for much of the way.