8 Figure Grid Reference

There's an article in this month's Trail (May) about 8 figure grid references. The point about them being good for Mountain Rescue to help find people is a good one, as they are more precise but I question the point that they make your navigation better. This is because when navigating I'd have thought that most people use the features of the map to guide them and don't say "I'll head to that trig point at 1256 3478". Whilst they do greatly improve descriptions of your route, I can't see that they'd make much difference when out on the hill.

Also, expecting someone who needs the help of mountain rescue to pinpoint their location to the nearest 10m is asking a little much. Anyway, rant over. Just wondering what other people thought about 8 figure grid references.

I don't think that 8- or 10-figure grid references help much with navigation, but they can help with finding things in the landscape, e.g. archaeological features, or help meet at a specific point.  So the trig point may be a reasonable use of an 8-fig GR.

You still have to find that GR on the ground, though, which may be simple if you're 'cheating' with GPS, but may be much more difficult if 'not cheating', and there are no obvious ground features that you can identify (but then you probably wouldn't choose such a point at which to place a waypoint...).

10-fig GRs give 1m accuracy.  You won't read the map to that accuracy, and your GPS won't be that accurate, unless you're using some form of referenced DPGS.

If you want to read 8-figure GRs off a 1:25k map, you could print out one of my vernier romers...

I have another script that produces a combined portland plotter and vernier romer, ueful for taking bearings as well as reading GRs.

Indeed CP, that's why i always give at least an 8 fig Gr and a 10 fig one when necessary.

Old womans Stone.

Include a little history in your walks. Pecsaetan - Ancient Derbyshire, Staffordshire and South Yorkshire - http://pecsaetan.weebly.com/

if 10-fig GRs give 1m accuracy, how on earth is anyone actually going to be able to see that on a map of any of the usual scales?

I used (probably could still but havent for a while) navigate to 8 figures and learnt to do so whilst preparing for my ML assessment.  Usually 6 figure is fine but there are times when getting down to 10m is handy but one has to bear in mind systematic errors which means, I think, getting to within 15m consistantly is pretty good.

10 figure...cant see how that is possible in practice

I always worked to six fig GRs (and still often do for simple day-to-day nav in good conditions). Then I went on a nav course and learnt the importance and practicality of precision across the board. The difference in accuracy between 100m and 10m could potentially be a matter of life and death in bad conditions on dangerous terrain.  Now I try to work to eight fig GRs (using 25K Harveys or OS maps) as much as possible.

Personally, I don't think ten fig GRs would be practical with conventional mapping in the field - just IMO of course.

Watching Highland Emergency on the box it has struck me many times how difficult it is for the chopper to find the casualty/ies, even when given a grid ref. It seems they are often flying around searching for anything from 5 to 20 mins.

I'd have thought that a large-as-possible (1.5x2m?) piece of very light bright orange fabric on the ground, held down with rocks/rucksacks/bottoms would help immensely, much more than worrying about 8-figure grid refs?

Thanks for that Twiglegs

Having been up there on Bamford Edge looking for that stone I would have found it easier with a tight GR

Haha, we should rename this place ArchaeologyMagic.

There's several sites on Eyam moor including the two lesser stone circles and a couple of cup and ringed marked stones, one covered by a carpet of heather, that definitely need a 10 fig Gr if you're to find them, with a gps of course.

Include a little history in your walks. Pecsaetan - Ancient Derbyshire, Staffordshire and South Yorkshire - http://pecsaetan.weebly.com/

You've hit the nail on the head there Geoff.  I remember the grid ref you gave me, far too close to read with a map and compass but easily confirmed with GPS.  21st Century technology surely means we can specifiy 8 or even 10 figure grid refs with the safe knowledge they can be located with precision.

(I am pissed, can you tell)? 

Asuming your GPS can get a fix on the satalite, or the accuracy of the GPS is upto it.  A GR that gives you accuracy to within 1 meter isnt much cop if your satalite can be upto 100 out.  If you need to be within 10 or 1 meter, wouldnt you be better using a larger scale map(still backed up by GPS mind)?

I might be in the minority, but I've always thought of a GPS as a good back up to your own nav skills.  I know there are times when they come into their own, but still think they should be viewed as secondry to map, compass and the ability to use them.

Sorry, rant over.

Large scale maps are a bit useless if the object you're looking for is under tree cover and not marked on any map though.

I do agree that map and compass should be your main nav tools though, but sometimes they're quite useless, especially if your marking a new discovery and absolutely need to find it again at a later date, sometimes in knee high heather on a featurless moor.

Include a little history in your walks. Pecsaetan - Ancient Derbyshire, Staffordshire and South Yorkshire - http://pecsaetan.weebly.com/

I actually use 8 figs quite a bit in my work.  Other uses:  bivi sites hidden away in rough ground, perhaps the start of a route up a crag, river crossing points, location of rare plants, locations for 'fixed point photography' etc etc. 

Let's remember, too, that a 100 x 100 box is 141 m diagonally, so if, say, a river runs NE, you are looking at a length of 141 m covered by a 6 fig grid ref.  I have started to record river crossing points on my phone, especially useful at night.  And that's a ten fig ref!

Twiglegs - wow, that Derbyshire ancient monuments site is great! Thanks for that.

I find 8 fig refs useful at times. Not often. But then I don't do a lot of geocaching.