Re: Active 10 GPS
- From: "Paul Saunders" <pvs1@xxxxxxxxxxxxxxxxxxxxx>
- Date: Sun, 28 Oct 2007 13:48:07 -0000
Ancient Brit wrote:
I used GPS in conjunction with OS maps this summer when I climbed all
284 Munros in Scotland and most of the tops
Nice one! Congrats on doing that!
so I am speaking with
experience of use in rough mountains in bad weather conditions.
Good, but I think you'll agree that what you did is a little more extreme
than what the average walker does.
HOWEVER the weather this summer was awful.
True, but many people avoid hill walking in bad weather. Perhaps this
correlates with their navigational skills, or lack of?
The other big advantage of GPS was
that it, when following a bearing, I could deviate from the straight
line to use the easiest way through the terrain and then come back to
line, where I would have tried to stay closer to the bearing using a
compass.
That's probably the biggest advantage for me. I hate walking in straight
lines. I like to negotiate the easiest ground so I treat the bearing to the
next waypoint as a rough guide only. So long as the arrow isn't pointing
backwards I'll get there eventually! ;-)
There are however DISADVANTAGES to using a GPS.
If you are using walking poles, unless you have a third hand, a
compass is more convenient for the continuous use needed in extreme
conditions than GPS.
That's an unfair criticism. You need extra hands for map and compass too, so
that's not specifically a GPS disadvantage.
I suppose for regular GPS use with walking poles a wrist GPS may be a better
option, although I haven't looked much into those and I don't think they're
very good on features. My technique when using poles is simply to glance at
the GPS occasionally. If I really need to use it continuously, I'll just use
one pole.
There are times when you have difficulty getting a satellite signal.
Especially in FORESTS,
I rarely have that problem, even in forests my 60CS keeps lock most of the
time, just as my GPS12 did. It only loses lock intermittently and it's
rarely a problem. It's more likely to lose lock in deep valleys, especially
with forests (particularly the Ystradfellte area), but even then, it's hard
to get lost in a valley, especially since it still gives me altitude data,
which makes it easy to pinpoint my position.
but try turning your GPS on in a blizzard and
see if you can get a fix. (There were blizzards this summer!!)
I haven't actually used it in a blizzard yet, but as Phil said, I wouldn't
"turn it on in a blizzard". It's always turned on. Keeping a lock is much
easier than getting one.
There are a few places, eg the Cuillin Mountains on Skye, where you
need to be able to mico-navigate the fine detail on the map
So you do that in advance on the computer, plotting a detailed route. But
with lots of cliffs around it's probably better to look where you're going
rather than staring at the GPS or a map.
The biggest problem, however, is that you CAN'T CHANGE YOUR ROUTE.
Yes you can! I do it all the time!
What happens if something happens which means you need to change your
route? This could be accident or injury. It could be because you have
underestimate the time for your walk. This summer for me it was
usually because the wind made it necessary for me to abandon walks.
For others it could be because of rain or cloud. If you haven't got a
map with you it is difficult to change your route safely.
No it's not, you just need to plan for it in advance.
(Remembering
it is in poor weather that you are most likely to want to change your
route)
All the more reason to have alternative plans if bad weather is likely. The
trick is not just to plan for where you'd like to go, but also to plan for
where you might end up going.
I've written about this many times on this newsgroup, but I'll reiterate for
your benefit. First I'll plot a tentative route, then I'll add numerous
additional waypoints to cover other useful features in the area, such as
summits and other prominent features, lakes, cols, key points such as path
junctions, bridges etc, and so on. Basically I'll input all the features
I'll be able to see and which may come in useful if I need to change my
route. You simply need to ask yourself the question "if I change my route,
where would I be likely to go instead?" Then add extra waypoints to cover
those eventualities.
Many of these waypoints can be used for navigational reference, even if you
don't want to visit them. For example, if I'm on trackless ground with zero
visibility, rather than reading off the grid ref and looking it up on the
map, I can simply look at the list of nearest waypoints to see where I am
relative to key features. So for example, if I know that Summit A is 2.3km
to the NE, Summit B is 4.6km to the NW and Lake A is 1.3km to the SW, then I
know where I am, relatively speaking. I don't need to know the actual grid
ref. (Actually it's much simpler just to look at the map display, but it is
sometimes useful to know the actual distances.)
Other waypoints could be critically important, for example those marking
escape routes off the mountain, if things turn bad, so it's wise to add
those in advance, just in case.
In practice, for many of my walks I don't bother entering a route at all, I
just scatter useful waypoints over the map. I don't even need to GOTO any of
them in good visibility, I can just glance at the map screen. Occasionally
it's handy to enter a GOTO if necessary, so I can basically make up a route
as I go, just using GOTOs for each one. This is much more flexible than
sticking to a fixed route.
Of course, fixed routes are more efficient if you specifically want to
follow a fixed route, but for my purposes I often do a lot of wandering to
find photo viewpoints, so fixed routes aren't so useful for me. And my photo
plans can often change quickly with a change in the weather, so I'll often
abandon waypoints I'd planned to visit and go a different way instead.
Having a load of waypoints loaded in advance gives you tremendous
flexiblity, and you rarely ever need to look at the map if you've chosen
them well. If you revisit the same areas frequently, it's advantageous to
save your waypoint collections in files so that you can load them quickly.
Also I think you will find learniing to use and understand the map
will enhance your enjoyment of your walk.
Knowing how to use and understand a map is a prerequisite for all this
waypoint plotting and route planning! How would you know where to place your
waypoints if you don't understand the map? It's not a question of placing
waypoints randomly, there's a certain amount of skill involved in choosing
key waypoints, especially if you're plotting a route near cliffs for
example. Too many waypoints could cause confusion. The fewer the waypoints,
the better the clarity, but you do need enough to cover all the critical
points.
What GPS are you using by the way?
Paul
--
http://www.wilderness-wales.co.uk/
http://www.wilderness-wales.co.uk/weblog/
http://www.wilderness-wales.co.uk/weblog/pic-of-the-day/henrhyd-falls/
.
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