GPS Datum for Ireland?
Q. I am visiting Kerry for the first time later this year and usually carry a Garmin GPS when out walking.
I understand you have to change grid reference over there.
Does anyone have experience in these matters?
James Brennan, Barrow In Furness
A. The Ordnance Survey of Ireland divide Northern and Southern Ireland into 25 x 100 km Grid Squares - lettered A to Z (there is no I) - 5 across and 5 down.
Each of these lettered 100km Grid Squares is then subdivided into 1km squares using the familiar blue grid lines.
So a Grid Reference in Ireland - say for the trig point on Knockawaddra in the Slive Mish Mountains - would look like:
Q 853 084
Where Q is the 100km Grid Square, 853 is the easting (to the nearest 100m) and 084 is the northing.
As with England, Scotland and Wales, there are a number of Datums you can use in conjunction with a GPS device - but if you want your GPS readings to match your map - 1:50 000 Ordnance Survey of Ireland Map (Discovery Series) - you should set your GPS to:
Position Format: Irish Grid
Map Datum: Ireland 1965
For more information on our GPS Waypoints, download our free GPS sample walk - c136 Mabbin Crag from Huck's Bridge - it includes sample GPS Data and links to the software and a cable vendor - so give it a go.
For more general information on GPS and GPS Devices - see Hill Skills > GPS Myths & Truths > GPS - The Myths and Truths - Part 1 and Hill Skills > GPS Myths & Truths > GPS - The Myths and Truths - Part 2
For fellow user Questions and Answers about GPS and GPS Devices
- see Q & A - GPS Waypoints
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Hope this is clear