The drawbacks:
IF you can get a signal. If you are in the bottom a narrow canyon and can
not see anough of the sky you may not get signals from enough satellites to
calcultate your location.
The size of the map on the screen will be much smaller than a paper map.
Off road your landmarks may not be as good as on road.
Batteries!
At this stage or the game I would add one not replace your other NAVAIDS. I
expect you would want a real map since the map on the screen will be
smaller. A real map can have GPS coordinates written on it so you can
program them in for route changes.
George in Las Vegas
George had some valid points that a map and compass should still be part of
your daypack. Batteries die, electronics can fail and signal reception can
be blocked.
Now, with that being said, it's hard to beat Garmin for good design and ease
of use. The Dakota 20 is a reasonably priced and featured unit. The nice
thing too is that it has an SD Card slot for detailed topo maps that can be
purchased separately. I believe MSRP is in the $350 range, but like all
electronics, you can usually find a better deal on the internet.
I use one of these:
https://buy.garmin.com/shop/shop.do?cID=144&pID=8705
The above does not have mapping software, and I still use a
(laminated) paper map because it does not have batteries to go flat.
I simply tag the location of the car and the camp on the GPS, and then
put it away. The GPS only comes out again if one gets a bit
'confused' and its getting dark, enabling some quick trianglation to
known points (or the ability to call up 'camp' and know that it is,
say, 1.87km that way when its pitch dark). Likewiase if I tip
something over and hang it up a tree for retreival the next day: tag
it on the GPS and if you cant find it again, whip out the GPS and
disciver that it is 87m over there.
Others who do want the mapping software go for something like this:
https://buy.garmin.com/shop/shop.do?cID=145&pID=309#
Purchasing metrics are weight, battery life, ability to hold mapping
software, and reception ability. The one that I use is pretty good on
the first two, no maps, and new ones will even work inside - mine
needs clear sky.
Personally, I think GPS's are great, but I dont ever want to be
beholden to one. I still 'work' with a (laminated) map, and only have
the GPS for backup.
As an aside, I found 'her-indoors' was much happier with me
dissappearing of into the bush knowing I had the GPS, even though I
first learnt how to use a compass 30 years ago.
There are so many out there to chose from and it can be confusing to
find just the right one... I know... I spent alot of time
researching them out before I bought mine. I know there are many
others out there that do as well or better though than mine... But I
settled on the Garmin GPSMap 60cx. I have used it in the deep
Colorado canyons and it never failed me to get a good signal. Maybe I
was lucky but I am very happy with this unit. I purchased separate
software from Garmin for better detailed mapping and it is amazing.
But as others have said, it will never replace a good compass and
paper map. Also, be sure to have extra batteries along as well! Good
luck with whatever you go with!
Steve
My old Etrex gps has a battery icon that shows how much power is
left. I carry extra batteries which will also fit in some of the
lights I carry. Never used it to find my way but like the extra
security. I'll usually mark where I parked and when I get in stand.
I like to check sunset time and need not worry about checking in
advance. I also carry an old lensatic compass. Had a compass in an
old Timex watch and battery gave out one evening as I was leaving the
woods. Also had a battery pendulum sight on a bow and battery gave
out just as a deer came within range. Also remember I time I got
turned around in the woods when my flashlight went out. Fortunately
that was in the morning ;)
I have a couple of GPS's; a Suunto wrist watch that shows elevation,
barometric pressure and has an electronic compass...and with that being
said, I would never go into an unknown area without a good Silva compass.
The electronic compass on my watch is accurate about 10% of the time (which
makes it an unworking gimmick) and I would not trust any battery operated
tool with my life. I'm very comfortable in the wilderness and certainly can
survive for a couple of days (as long as hypothermia doesn't become part of
the equation) and always rely on a good map and compass to help me sort
things out.
When I was a young man, I was rabbit hunting on a 60 acre triangle of
land...thick underbrush and heavy clouds. Two sides of the property was
bordered with roads with the third side on a swamp that I could not cross. I
got so twisted up in that mess, I walked in circles for a couple of hours
trying to find my way out. I finally sat myself down, regained my composure
and was able to follow road noise when vehicles passed. I never went into
the woods without a compass after that.
I have two Silva Ranger Type 15CL and swear by them (see the link
below). One feature that I find invaluable is the moveable gate to
compensate for magnetic declination so that once set, always yields
true north bearings which directly relate to topographic maps.
The compass base plate has three scales: 1:50000, 1:25000 and 1:24000
(the most common for USGS topo maps). It also boats an inclination
indicator which floats freely inside the compass housing and will
indicate inclines from 0 to 90 degrees in both directions.
http://www.tech4o.com/p-41-ranger-515-cl-compass.aspx
I keep one compass in my backpack and another always with me in my
vehicle along with a magnesium fire starter, a pocket folding diamond
knife sharpener and a folding 440C knife kept razor sharp.
Better to have it and not need it than to need it and not have it !