Re: [Paddlewise] GPS options (again)

Joe Pylka wrote:
> 
>     ...<lots of good advice snipped>...
>     
> The Garmin 12
> is supposed to be pretty good in this regard, with well over 12 hours of
> battery life.

The battery life of the Garmin 12 depends on the hardware platform,
which has changed occasionally along with the software version. 
Software versions *prior* to (but not including) 3.50 were rated at a 12
hour battery life (with alkalines), which proved to be a reasonably
accurate rating. Software versions 3.5x up to (but not including) 4.0
were rated at 12 hours, but most of these had an improved hardware
platform that allowed for 16-20 (or more) hours of usage, based on
numerous reports from users. I had a 3.52 that provided about 18 hours.
Versions 4.xx are rated at 24 hours, and that is accurate based on my
observations. The Garmin 12 is an excellent value at about $150 new. You
can probably find a used one for less than that, but as the above
suggests, make sure you get version 4.xx or you will end up paying more
in the long run.

>     I've also run across a curious difficulty here...  Many brands of AA
> batteries now come with the builtin battery tester.  Turns out these are too
> thick to be put into my GPS without getting stuck.  So I have to search for
> alkaline cells without that feature or else rip the wrapping off the
> batteries.

This problem with the Garmin 38 is easily solved. The problem is with
the longitudinal ridges in the battery compartment. Garmin provided a
reaming device to most of their dealers that can be used to shave down
these ridges. They fixed this problem on later models, but you still
might be able to find a dealer that has a reamer. If not, it is easy to
do yourself, either with the right size drill bit (you need the type of
bit that drills a "plug"--it has to be sharp, and you use it by hand,
*not* on the drill), or alternatively by wrapping some sand paper on a
dowel and sanding down the ridges. I used this latter approach on a 38
and it was quick, easy, and effective.

By the way, I have found that the best way to use a GPS when sea
kayaking is to mark up your chart with a "constellation" of
brightly-colored waypoints (at key locations, such as entrances to
coves, channels, locations off of points or other prominent features,
and intervals along the shoreline), and then scan these marked charts
into your computer (using a flatbed scanner). You can then use software
that allows you to enter the coordinates of these waypoints into your
GPS simply by double-clicking on each waypoint on the scanned chart. 
You can very quickly transfer a hundred waypoints into a file, and it
then takes just a few seconds to download the appropriate file (or
files) into your GPS, depending on the charts that you will be using on
your trip. When you are paddling along, the moving map display on your
GPS will show your position relative to the portion of the waypoint
constellation through which you are paddling, and by glancing at the
corresponding (brightly-colored) constellation on your chart, you can
see immediately where you are.  

Dan Hagen
(owner of too many GPS receivers)
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