Teaching Scouts How GPS Works

Outdoor Life
Outdoors
Teaching Scouts How GPS Works
by Barry Gervais
With the advent of Global Positioning Systems
Adding a GPS makes it a little more
(GPS), navigation has never been more accurate
or easier. From a Scout leader perspective, it also
fun than just hiking.
makes six hour hikes easier than ever to plan. Add
in some geocaching and hiking becomes a treasure
hunt. One of the best web sites to find caches is
http://www.geocaching.com/.
Each geocache location will show a series of numbers, so it
is important that your Scouts know what all the numbers like
N45 16.909 W75 45.722 really mean. While the numbers seem
a little bit scary at first, they really are nothing more than a grid
location. The location mentioned above is actually a tree in a
park in Barrhaven, Nepean, Ontario. You don’t believe it do you?
Go to http://maps.google.ca and enter the number given above
and you will see for yourself.
Yes, that tree directly below the letter “A” is the tree I stood
under to take the location. Why isn’t the bottom of the “A” directly
on the tree? Well, Global Positioning Systems have slight errors
dependant on the weather and the number of satellites you
pick up. When I determined the location with my GPS it was
cloudy so my navigation was plus or minus 9 metres.
How do you go about explaining this system to your
Scouts? Here is a suggested meeting plan which takes about 20
minutes to review. You can either use this one as an example,
or go out near your meeting place and find three locations that
everyone knows. In my case, I chose the Walter Baker Sports
Center, Barrhaven Public School and St. Patrick’s Catholic School.
Photo: Barry Gervais
July 10 – 17, 2010
Jambo 9 will be held at Camp BEL, located in Dorchester near London Ontario.
On behalf of the staff, I would like to invite all Scouts, Scouters, Guides and Guiders within the
World Brotherhood of Scouting and Guiding, to be part of this wonderful Jamboree experience.
We will have seven main area villages for day
programming plus the expanded overnight
Brownsea Challenge with a full 5 nights of sub
camp program and two nights of camp-wide
program. There are two levels of canoe action,
two levels of hikes, rappel towers, climbing wall,
archery, blacksmith forge, rifle ranges, and much
more! Special Opening and Closing ceremonies
will add to your Jamboree Adventure.
Cost for the Jamboree is $225/youth, and
$100/leader, plus your troop registration fee.
This includes everything except your food and
transportation.
Download your very own copy of the
Jambo Program Information Package
from www.greatlakesjamboree.net to
share with your youth. Start making plans now
for a GREAT summer experience!
Steve Locke (519)383-7947
Deadline for registration is May 31, 2010 or 600 participants. See you there!
Step 1: Using graph paper, label a grid system with 0, 0 in the
middle and an X, Y cross. (See Diagram #1.) Label your axis
North and South along the vertical axis and East and West
along the horizontal. Tell the Scouts to pretend that the center
of the earth is at the 0, 0 point and your meeting place is at N5
and E3. Ask them how they would get there from the center
of the earth. The answer would be to simply go 5 squares up
(North) and 3 to the East and draw a dot on that point marking
your meeting place.
Diagram 1
NOTE: Use graph paper
with a fairly large grid to
achieve the best results.
38 ScoutingLife.ca | October 2009

Step 2: Next, pretend to go to the parliament buildings from
your meeting place. Say the parliament buildings are at S2,
W1. Calculated from your meeting place location, the correct
answer should be down 7 (5+2) and over 4 (3+1).
Step 3: Ask them what would happen if the parliament buildings
were actually at S2.5 and W1.5. The answer would be 7.5
and 4.5 respectively. Congratulations; now they understand
how GPS works with all those numbers.
Step 4: You may notice that GPS uses three sets of numbers
(i.e. N45 16.944). The third sets are simply because the earth
is large and we need to go down to this level to determine
the exact location.
The Challenge
Show the Scouts Diagram #2 with the three GPS locations
marked on it, followed by the Google picture directly to the right.
Make sure they understand that the diagrams show the same
three locations, the one below right is simply a satellite picture.
Tell them to write down the following number N45 16.909
W 75 45.722. Using the numbers given to them from the three
locations in Diagram #2, navigate using addition and subtraction
to the point above. This is no different than going from N5
E3 to S2 W1 in our training earlier.
Ask them to put an “X” where they think the mystery location
is, and as you already know, it is the tree. After my Scouts
finished guessing I took my GPS and we walked to that location.
They ended up standing under the tree.
Take a Hike
Now that you know how it works, take them out for a geocaching
hike (three or four caches make a great six hour hike).
Treasure hunting makes it a little more fun than just hiking.
For more information on GPS hiking, go to the geocaching
website mentioned above.m
— Scouter Barry Gervais enjoys leading the 23rd Nepean Scouts
on geocaching hikes. Find another GPS article in the May 2008
issue of the Leader Magazine.
Diagram 2
(Google Map diagram)
(Satellite Map)
NOTE: A pdf version of
diagram 2 is available
for download at
www.scoutinglife.ca.
ScoutingLife.ca | October 2009 39