[pct-l] Halfmile at the kickoff

Halfmile halfmile at pctmap.net
Thu Apr 16 14:21:05 CDT 2009


I don't know of any GPS app that will practically do that for a PCT
hiker but a new iPhone GPS app appears almost daily so something might
be out there.

Since my maps at http://www.pctmap.net are all pdf files it is
possible to view them with an iPhone pdf viewer app, however the pdf
files are not geo-referenced, an no iPhone app supports that either,
so it's like viewing paper maps in your iPhone.

I have tested several pdf viewer apps and my favorite is Felaur PDF.
I like it because it's default zoom view is 100% and  when you open a
multi page pdf file it defaults to the last page you viewed and you
can download pdfs directly from a url. I have set up this url for
downloading directly from an iphone:


Change the "ca"  or "a" part of the url and you can download
California a - r or Oregon b - c. For example:


Downloads will be faster from a wifi connection.

There are several USGS topo quad map viewer apps which look
interesting to me but they really are limited in usefulness for PCT
hikers as the PCT usually is not shown on USGS topo quad maps.
Basically it's like having a paper USGS quad map in your iPhone with
the added benefit of showing your location on the map. Downloading the
quads is a lengthy process (2 - 5 min. each). I have used both
iTopoMaps and Topo Maps apps. If you have never used paper topo maps
you will probably just think this is strange and clunky compared to
slick online maps, but if you are into maps it's kind of cool.

The iPhone's GPS can accurately give your position which is very
useful for trail navigation. UTM coordinates are much easier to work
with, but you will need a GPS app and good paper maps that have UTM
grids printed on them for this to work. PCT maps with UTM grids would
be my maps at www.pctmap.net, Erik's PCT Atlas, or the Forest Service
maps. Since the WIlderness Press Guidebooks have no UTM (and no
Latitude and Longitude) they are limited in usefulness for GPS users.

iPhone apps which I have used and accurately display UTM coordinates
include iGCT, Basic GPS, Motion X GPS and GPS Kit. My favorites are
Basic GPS (it's very basic just displays your position) and Motion X
GPS which attempts to be a more full featured GPS with go to
navigation to waypoints, etc. The only iPhone apps that I have found
that currently import data are GPS Kit and Trails. Trails only imports
tracks however and does not understand the concept of true waypoints.

I have been experimenting with GPS Kit's file importing and have half
mile and other waypoints shared on the GPS Kit web site for California
Section A - D right now. If any other GPS Kit users are out there I
would welcome any comments on how this is working. Since the waypoints
are spaced every half mile it's very easy to see your location even
without online maps. It works especially well in conjunction with my
printable maps. (GPS Kit might show your location between A163 and
A164 which you could easily see on the printed maps). I can share more
waypoints if anyone is interested.

It's worth noting that no iPhone app I am aware of will accurately
display coordinates in the NAD27 datum and all the paper maps (except
mine) use NAD27 (the iPhone uses WSG84). The difference between these
two map datums varies depending in what part of the country you are
in, but along the PCT will be a little over 1/10 mile difference. You
can easily add 80 to the easting UTM number and subtract 200 from the
northing UTM number to compensate reasonably accurately or just
eyeball by moving down and to the right once you have done this a few

Anyway, I have rambled on enough for now.


On Thu, Apr 16, 2009 at 8:21 AM, Tobin Van Pelt <tobin.van.pelt at mac.com> wrote:
> Halfmile -
> I will look for you at kickoff.  I have a new 3G GPS enabled
> iphone ... battery life is not great but I am going to have to
> deal ... may augment with small solar unit ... still testing.
> BTW - do you know of any way of preloading maps on to the iphone
> device?  All of the GPS apps that I have looked at seem to only load
> when needed and then cache.  I would (for obvious reasons), want to
> download as much as possible in advance and then use when out of
> coverage.  Have not researched this a bunch yet ... and don't have
> time now to write my own app.
> Thanks.
> Tobin

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