GPS - Irish Coordinate System

[SeaHound1]

I posted this over in the "Europe" section but did not get a reply, maybe I'll get one here...

I'm planning some diving in Ireland this summer and I'm researching sites. Some of the Irish web sites list GPS coordinates but when I plug the numbers in to my Garmin Mapsource program some of the sites show up on dry land! I'm trying to figure out what datum (like WGS 84) they are using and what format they list the coordinates in. Is it: dd mm ss (degrees, minutes, seconds) or what?

Heres an example:
The Folio - Location: GPS: N 51 52 86 W 7 41 34
Three Mile Rock - Location S.E. of Hook Head. GPS: N 52 54 65 W 6 51 47

Notice the third pair of numbers that is greater than 60 (seconds)?

Thanks for any feedback.
Michael

 

[ba_hiker]

I posted this over in the "Europe" section but did not get a reply, maybe I'll get one here...

I'm planning some diving in Ireland this summer and I'm researching sites. Some of the Irish web sites list GPS coordinates but when I plug the numbers in to my Garmin Mapsource program some of the sites show up on dry land! I'm trying to figure out what datum (like WGS 84) they are using and what format they list the coordinates in. Is it: dd mm ss (degrees, minutes, seconds) or what?

Heres an example:
The Folio - Location: GPS: N 51 52 86 W 7 41 34
Three Mile Rock - Location S.E. of Hook Head. GPS: N 52 54 65 W 6 51 47

Notice the third pair of numbers that is greater than 60 (seconds)?

Thanks for any feedback.
Michael

Normally the datum used for a map is printed some where on the map normally in the legend area, or sometimes in a separate publication as an overview guide. a common datum for irish maps (based on 'ordinance surveys') is Ireland 69 or Ireland 95. Ireland 95 is sometimes called OSi, OSNI, or IRENET95. see:

http://www.osni.gov.uk/2.2_a_new_coordinate_system_for_ireland.pdf

 

[SeaHound1]

That's exactly what I'm trying to find out; what datum are the using? I'm finding these dive site numbers on Irish web sites, not maps. I find similar sets of numbers on different sites but they never state the datum.

For example here are two different ways I've found the wreck Folia listed:
N51 52 86 W 7 41 34
N51 52 086 W 7 41 034

If I knew which datum they were using I'd be off to a good start, then I could figure which number format they were using; dd mm ss, or dd mm.mmm.

Thanks
MPM

 

[ba_hiker]

That's exactly what I'm trying to find out; what datum are the using? I'm finding these dive site numbers on Irish web sites, not maps. I find similar sets of numbers on different sites but they never state the datum.

For example here are two different ways I've found the wreck Folia listed:
N51 52 86 W 7 41 34
N51 52 086 W 7 41 034

If I knew which datum they were using I'd be off to a good start, then I could figure which number format they were using; dd mm ss, or dd mm.mmm.

Thanks
MPM

well at first glance, i notice that 86 (or 086) is not a seconds value. BUT the value 86 and 086. interpreted as a decimal value are miles apart, and because of map datum.

From Irish Wrecks On-Line - Folia SS (No. 397) i get three bits of info...

Latitude (GPS): 51 52.86 North
Longitude (GPS): 07 41.34 West

this confirms the lat and long as decimal fractions and says that its measured by gps.
This normally means that WGS 84 datum. At UK diving UK Diving they list the location as:

Lat / Long : 51 ° 55 ' 25 '' North - 7 ° 43' 35'' West
System used to obtain Long / Lat : Approximate

Clearly hh mm ss format, and is miles from the other location. But it is listed as 'approximate'.