The document provides an in-depth overview of the Global Positioning System (GPS), including its components, operations, features, and practical applications for navigation. It explains how GPS receivers work by triangulating signals from satellites to determine accurate location and provides detailed instructions for using various Garmin GPS devices. Additionally, it discusses the importance of waypoints, routes, and the integration of GPS with paper charts for effective navigation.

1. Introduction GPS
American Sailing Institute
Prepared by Sherri
Gregory
Most illustrations copied from Garmin
Owners Manuals and Reference Guides
Ver 2 2017
1

2. What is GPS
•GPS (Global Positioning System) was
developed by the U.S. Department of
Defense then made available to the
public
• Allows you to know to a high degree
of
accuracy where you are
• Provides exact local time
• Presents location to your GPS
receiver
in terms of latitude and longitude.
2

3. GPS
Components
• Space Satellite
Constellation
—At least 24 active satellites plus
spares
—Each satellite contains atomic clocks
and signals to determine position of
itself and other satellites
• Operational Ground based
Monitors
— Ensures accurate positioning
information
• User GPS unit
—Contains antenna, amplifier, signal
decoding, computer, display screen with
controls *

4. How GPS (Global Positioning System)
works
4
•The GPS receiver receives and compares signals from 3 Or 4
orbiting satellites that are in the line of sight of the receiver.
• Each satellite transmits its exact location along with a time signal.
•The GPS receiver uses this data to determine its distance from each
o
T the satellites.
• Once the position and distance of each satellite is known, the GPS
receiver
calculates it’ s current location which is the position where all these
LOPs
CfOSS.
Diagram from
Ben Levitan
and Lawrence
Harte:
Introduction to
Satellite
systems

5. 5
BASIC GPS Features
•SateIIite tracking (shows positions and
signal quality)
•Presents detailed system status
•DispIays latitude and longitude
•DispIays exact time
•Shows where you've been (track) and
speed
•Projects required direction, speed and
time
to a destination
•Shows distance and direction to a
desired route (Cross track error)
•OptionaIIy contains nautical charts

6. “From Power Squadron Introduction to GPS
Manual
6
GPS is used to answer
these questions*
• Where am I now?
• What is my course from here to
destination?
• How far is my destinations?
• How fast am I going?
• How long will it take to get there?
• Am I still on course? If not, what
correction is
needed?
• Are we there yet?

7. 7
GPS
Operation

8. 8
Activating a Garmin GPS
• Press the On button to turn on the unit
• Often requires agreeing to
warning message
• These messages differ
depending on unit
• Note: This button usually also
controls
backlight intensity.

9. GPSMap 78: Button
s
•Quit — Return to
Previous menu/page
•ON/Off/backlight
• Find/MOB — Press to
open search menu.
Hold to store current
location as a waypoint and begin navigation to it.
•Zoom In, Zoom Out
•Page — Scroll through main pages
•Menu — Open menu for current page, press
twice for
main menu
•Enter/Mark — Press to select options. Hold to
save

10. Garmin 72 Buttons (clockwise from
lower left)
QUIT — Escape from current screen and
back to previous
*-$ — Turn unit on/off and
adjust background light intensity
GOTO — Provides a menu for
selecting waypoint to navigate to. Press
twice for MOB (Man Overboard). Directs
you back to that location.
IN — ZOOM map or highway screen in
OUT — ZOOM map or highway screen
out
PAGE — Cycle though a set of preset
screens
MENU — Access main menu or
menu applicable to current page
ENTER — Execute an action. Press
for 3 seconds to MARK the current

11. GPSmap 182 Keyboard
Interface
Keys
1
1

12. GPSmap 547 Keyboard
Automatic backlight
sensor Power key
Device keys
microSD memory card
slots
Device Keys
Turns on and off the
device when held.
Adjusts the backlight and color mOde when quickly
pressed and released.
Zooms out of a chart or view.
Zooms in to a chart or view.
Scrolls, highlights options, and moves the cursor.
SELECT
BACK
MARK
HOME
MENU
Acknowledges messages and selects
options. Returns to the previous screen.
Saves the present location as a
waypoint. Returns to the Home screen.
Opens a menu of options for the page,
when applicable.
Closes a menu, when applicable.

13. GPSmap 741 Touchscreen
13
Power key
Automatic backlight
sensor Touchscreen
microSD” memory card
slots

14. 14
GPSmap
741
Using the Touchscreen
• Tap the screen to select an item.
• Drag or swipe your finger across the screen to pan or
scroll.
• Pinch two fingers together to zoom out.
• Spread two fingers apai1 to zoom in.
Locking the Touchscreen
You can lock the touchscreen to prevent inadvertent
screen touches.
1 Select C'j.
2 Select Lock Touchscreen.

15. 15
Cleaning the
Screen
• Cleaners containing ammonia will harm
the
anti-reflective coating.
• The device is coated with a special anti-
reflective coating which is very
sensitive to skin oils, waxes, and
abrasive cleaners.
—Apply an eyeglass lens cleaner specified as
safe for anti- reflective coatings to the cloth.
—Gently wipe the screen with a soft, clean, lint-
free

16. Main Menu — Can get to everything from
here
usually by pressing “Menu” key twice
GPSMAP 182C GPS 72
Main Menu
Paoe

17. Sometime the Home
button brings you to the
main menu
17
• In the GPSMAP
547/741
Everything can be
accessed from
Home.
• Menu order can
be changed.
• Scroll up/down
to see entire
Homemenu:
GPSMAP 547
Navigation Chart
Nav Info
Man
Overboard
Gauges
Settings
Customize
Home

18. Commonly accessed GPS Pages
• Map
• Satellites
• Compass or Pointer
• Highway screen
• Various Setup screens
• Trip Computer or Gauges or Numbers
• Route and Waypoint lists and detail information
• Route and Waypoints edit screens
• Active Route
• Track list
Note: In some units some of these can be scrolled
using the Page button. In some units you can
customize the Page button to just show your
favorites.

19. Pages
Most units have a “Page” button to scroll
through the most popular pages. Some have
a fixed set of pages while in other units you can
select what to show.
Some units such as the GPSMAP 547/741 don't
have a Page button. (Example below is from the
GPSMAP 182C. The pages are fixed.)
Hap
Page
Pointer P
age
Numbers
Psge
Highway Pa
ge
/ctive RDute
Page

20. MAP PAGE
2
1
Uses while underway:
—View waypoints and routes
—Measure distances to objects
— Know your location on a chart and
see your relationship to landmarks and
depth ranges
—Create “Goto” routes
—Follow tracks
—Zoom in and Out

21. MAP PAGE
2
1
Uses while underway:
—View waypoints and routes
—Measure distances to objects
— Know your location on a chart and
see your relationship to landmarks and
depth ranges
—Create “Goto” routes
—Follow tracks
—Zoom in and Out

22. Compass May be electronic
(true compass) or GPS controlled
(sometimes called Pointer)
22
Example: GPSMap 182C
•GPS controlled; It only
works when you are
moving.
•Your track is shown at the
top
of the ring.
•The pointer is the bearing
or course to your
destination.
•If the arrow points up you
are moving toward your
destination.
•To use for navigation,
GO
T
O
”oirne
r

23. Highway
Page
23
Example from Garmin GPS
72
This page shows a 3D view
of your course, with the
waypoint to which you are
currently navigating ahead
of you.
It also includes user
selectable data fields
(number and size of fields
can also be changed)
highway
Page
LI.67
•
Highway
Page

24. Trip Computer, Trip Gauge
or
Numbers Page
24
A similar page can
be found on most
GPS Units.
In the GPS 72 (seen
here) these fields
are not changeable.
In other units you
can determine the
number of items to
show and which
data items (or
numbers) to show.

25. 25
Check or Change: Basic
Settings
•SimuIator mode on/off (simulator mode is
also called GPS off or Demo Mode in some
units)
•North Reference: Magnetic or True
•Distance: Nautical Miles or Statute Miles
•Depth: Feet, fathoms or meters
•Data fields (numbers): How many
fields and contents to display on any
applicable screen

26. 26
Check or Change: Map
Options
• Change orientation North Up/Track
Up/Course Up
• Change Level of Detail
• View and select/deselect Charts
• Change Size of Waypoints
• Size of Navaid symbols
• Display Heading Line/Bearing Line/Course
Line
• Change text size and zoom range

27. 27
Check or Change -
Alarms
• Arrival: Sets an alarm to sound when
you are within a specified distance or time
from a turn or a destination.
• Anchor Drag: Sets an alarm to sound
when you exceed a specified drift distance
while anchored.
• Off Course: Sets an alarm to sound when
you are off course by a specified distance
(also called cross track error)

28. 28
Examples of Selectable Data Fields or
Numbers
• Accuracy
• Bearing
(direction)*
• Course
tdirection)*
• Depth
• Dist to
Destination
• Dist to Next
• ETA at Destination
• ETA at Next
• Location (lat/long)
• Max Speed
• Moving Avg
Speed
• Off Course
(distance)
• Pointer
• Speed
• Time of Day
• Time to Destination
• Time to next
• To Course
(direction)*
• Total Avg Speed
• Total Trip Timer
• Track (direction)*
• Trip Odometer

29. Chart Latitude and Longitude
display
29
Caution: In most GPS units the only way to
see your current position is to have it
displayed as an optional data item or
number
.
The lat/Ion that appear on the map screen is
generally the lat/Ion of the position of the
pointer or cursor.
0.P‘ , ” * ’ s „ „ e
Boat position
(optional)
Pointer (cursor)
position
' --- ””” -
-
:rdinaes

30. 30
Useful (but sometimes
confusing) data fields used
for navigation
Bearing — Compass direction from your
current location to a destination point
• Track —Course the boat has been sailing
over ground or COG.
• Course — Desired path of travel from the
point
navigation is initiated to your
destination waypoint (also referred to
as rhumb line)
Heading — There is no GPS readout for
your heading
which is the compass course you are
steering. GPS

31. A course has been established from start to
destination
(compass directions are for illustration only).
North is up.
Course =
320
Destination
Bearing -
275
To Course -
210
Track -
350
Start
J1

32. Waypoint
s
•Waypoints are specific locations that you will
use on your journey.
•They can indicate points along a route as well as
your
destination.
•They can also indicate an obstruction or other
danger point.
•GPS units have two ways to set up waypoints:
directly from a waypoint page, and using the map
page to point to the desired location of a waypoint
•Most units can also import waypoints from
other sources via data chip, direct computer
etc 3
2

33. 33
Creating a Waypoint
• The easiest way to create a waypoint
using a GPS unit is by using the cursor to
locate a position on the Map page.
• In some units just press “Enter/Mark” to
create a waypoint at that position (GPSMAP
182). In
some units (GPSMAP 547/741) this is done via
the “Nav Info” menu option.
• You can also create a new waypoint by
editing an existing one. The original
waypoint will not be retained.

34. 34
Waypoints
Names
• When you create a new waypoint
it's automatically
given a name (often a sequential
number) by the
unit.
• It is recommended that you change
the name to reflect something
meaningful about the location or
route.

35. Man Overboard
35
• All units have a quick way to mark the
spot
where you are currently and navigate to
it.
• This is initiated by pressing “MOB”.
Caution: Make sure you know where
MOB
is on the GPS you are using

36. Proximity Waypoint/Proximity
Alarm
36
• Lets you define an alarm circle
around a
waypoint
• Useful for identifying obstructions
• You can select the radius of the circle.
Example from
GPSMAP 182C

37. 37
GPS Text Editor
Can be cumbersome but
necessary for some actions such
as editing waypoints:
Waypoint Name
Waypoint Symbol
Latitude and Longitude

38. 38
GPS Text
Editors
• Each GPS has its own method for text
editing.
• Two common methods:
—For each character scroll through the
entire set of letter, numbers and symbols
to find the character you want (GPS 72,
GPSMAP 182C)
—The Edit page displays all available
characters and you use the cursor to
select the character you want (GPSMAP
78, GPSMap 547/741)

39. 39
Route
s
• A route is a path that you want to
navigate
• It's made up of two or more
connected waypoints.
• You can create waypoints first then
connect them to create a route
or
• You can establish the beginning
and
end waypoints first then fill in the
“turns”

40. 40
Three methods of establishing a
route
• Create a fixed route to follow
—Use for planning or if your route contains
multiple
waypoints
—Use if there are obstacles you need to avoid
between your current location and
destination.
• Use “Go To”
— Use when your current location is the
starting point and the course is straight to your
destination with no obstacles nearby
—Easy to use
• Follow an existing track
Note: Your map page may show your initial course or
current bearing to your destination.Check your

41. 41
“Go To”
Cautions
• Stay on your initial course if obstacles are in
the
area
• If necessary set the Proximity alarm on
obstacles
• Know your position and track by plotting
fixes on your paper chart at regular intervals.
If your bearing (direction to your
destination) changes check your chart to
make sure that your current bearing will
take you safely to your destination.

42. 42
Creating a Fixed
Route
Fixed Routes can be established in
a number of ways
—Directly from a Route Page by selecting
existing waypoints that make up the
route.
—Using the map page to draw a route
—Most units can also import routes from
other sources via data chip, direct
computer transfer, wi-fi etc.)

43. 43
Route
To
(Available on GPSMAP 547/741)
• A temporary route that enhances
“GoTo”
• Starts with a straight route from your
location to a destination then allows
you to add turns along the way.
• Makes it easier to avoid obstacles
and navigate around land masses.
• The route may be saved later if
desired.

44. 44
Activating a
Route
• If you want to use “Go To”, it's easiest
to just select a destination location
on the map screen. Follow the
instructions to navigate to that
point.
• If a stored route or waypoint is
desired, use the Find Key (GPS 72,
GPSMAP 182C) or Nav Info (GPSMAP
547/741) to select the route or
waypoint.

45. 45
Transferring data from
an externai source
• It is time consuming and cumbersome to
set up routes and waypoints directly on
handheld GPS units because of size and
editing limitations.
• You may want to quickly load your own
waypoints and routes on an ASI chartplotter
for your timeshare. (GPSMAP 547/741 only)
• Most units have a way to import and
export data from another source such as a
computer, tablet or another GPS unit

46. 46
Exampies of Data
Transfer
Methods
• Direct Transfer of files from Garmin
Homeport
to a Garmin handheld using a USB cable
(GPSMAP 78x)
• Load a GPX file or a file from Garmin
Homeport onto a MicroSD card and insert
card on a chartplotter (GPSMAP 547/741)
• Transfer all routes and waypoints from
Bluechart Mobile to a chartplotter via local
WiFi (GPSMAP 547/741)
• Some units use proprietary chips or

47. Practical uses
of
How can these waypoints assist
in navigation?
(“North Buoy” is FI(2+1)G6S;
“South Buoy” is “1”,FI G4S)
NORTH B O
JEFFERSON
ILLER TO
SOUTH BUOY
ST CLAIR L

48. GPS with Paper
Charts
4
8

49. Some reasons to Use a
Paper Chart with GPS
• Some GPS units don't include charts (GPS
72
units)
• Battery/power source unavailable
• Overlapping charts, missing expected
charts
• Other GPS unit malfunction
• GPS signal interruption
• Paper chai1 provides the big view and
detail at the same time.
• You could have programmed your GPS
incorrectly
49

50. Planning — GPS and Paper
Charts
• Establish waypoints (and routes) including danger
points and enter them on
your GPS. (If using your own
GPS,
it’ s easiest to enter them on your computer and
then
download)
—Use short meaningful names
— Make a list of waypoints with name, lat,
long and description of location
• Draw your route on your paper chart including
hourly
projected DR plots based on your estimated
speed and
time Of departure. Indicate your waypoints on
your paper chart as shown below.
@ sC01
-Waypoint symbol/name used on paper chart
(USPS) (Symbol is omitted if waypoint is also a nav
aid)

51. Underway GPS and Paper
Charts
• Each hour use your GPS to determine your
location and plot this fix on your paper chart
(see plotting conventions below).
Occasionally take compass bearings and
GPS fixes simultaneously to test your ability
to take compass bearings and check your
GPS if you suspect a problem.
2045 GPS - GPS fix plotted on a paper chart
(USPS)
SC01
2045 GPS
- GPS fix plotted on a
waypoint
51

52. Jefferson Beach Marina N 42 28.042 W 82 52.503
North Buoy N 42 25.503 W 52 51 .5 l P
South Buoy N 42 27.709 W S2 51.719
St. Clair Light N 42 27.915 W 82 45.250
Waypoint Exercise
Create waypoints for these four locations in Lake St
Clair. Use short meaningful names for each:
5
2

53. Jeìtćrson Beach Marina N 42 28.(ì42 W 82.52..5f).3
North Ruoy N 42 28.505 W 82 û l.û 10
Souih Buoy N 42 27.709 W 82 51.719
St. Clair Light N 42 27.915 W 82 45.250
Exercise
result
(from map
page)
ORT BU
EFFERSON
OU H BUO