NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Latitude AND Longitude by Noon Sun+GPS
From: Kieran Kelly
Date: 2004 Jan 25, 14:07 +1100
From: Kieran Kelly
Date: 2004 Jan 25, 14:07 +1100
Frank Reed
wrote
Celestial navigation is no longer necessary unless there is a serious emergency (complete breakdown of all electronics, disruption of the entire GPS satellite network). Under those emergency circumstances, a boater would be doing very well if he or she could get latitude to within 3 or 4 miles and longitude to within 20 or 30 miles.
Celestial navigation is no longer necessary unless there is a serious emergency (complete breakdown of all electronics, disruption of the entire GPS satellite network). Under those emergency circumstances, a boater would be doing very well if he or she could get latitude to within 3 or 4 miles and longitude to within 20 or 30 miles.
Frank makes two
assumptions here:
1) That the
modern GPS is a reliable tool. I suggest it is
not
2) That most GPS units
purchased are by ocean navigators. Here again I beg to
differ.
Re Point
1)
The GPS unit at sea I
understand is a very reliable and lifesaving instrument. The reason: The
horizon on a boat is always visible. On land the horizon is often not visible
for two reasons:
1) Overhanging tree
and scrub cover and/or
2) The presence of
gullies and gorges
I promise all list
members from bitter experience that a GPS unit will not work in the dense scrubs
of the tropical Australian deserts. It will also not work in the depth of the
gorge country of Australia Kimberley plateau or in the deep ravines of the
Victoria River. For example I went for four days several years ago in the Depot
Creek gorge walking approx 15 km per day and did not once get a GPS signal or
location. It would pick up the occasional satellite traversing overhead but then
lose it by the time another satellite came over. (Obviously if you could
get out of these gorges you could get a fix. unfortunately in some places you
cant get out.)
I always take a GPS
unit on my expeditions mainly as a safety measure and for marking important
anthropological sites such as rock art or carvings. I do this because large
chunks of Central Australia to this day have not been surveyed. However I would
never rely on a GPS unit for terrestrial navigation, that's why God gave us
compasses. I have a Garmin 12 and it seems to
need a minimum of 3 satellites fairly low down on the horizon and widely spaced
to even tell me I am in Australia!
Re Point
2)
The majority of GPS units
sold in Australia I have been informed go to the recreational hiker and
backpacker market. This is possibly due to the large number of tourists here and
the smaller number of boaters. However I must confess that I don't know the
exact reason. Whether this is the same overseas I don't
know.
So Franks assertion that
celestial navigation is no longer necessary unless there is an emergency is
about half right. If there is an emergency you may not have to rely on CN as a
last resort but you had better have something other than a GPS
unit.
Sorry to intrude dusty old
terrestrial navigation onto this site but if I had relied on GPS units for my
expeditions the ants and dingoes would long ago have supped on my bones in
the great Outback.
Kieran
Kelly
Sydney
Australia
