1. Introduction to Navigation
Chapter 12
Introduction to Navigation

2. Lesson Objectives Selecting and keeping charts current
Constructing and reading charts
Use of navigation tools
Select, adjust, mount, and correct a compass
Plot a course and measure direction
SSSpptChpt12Navigation ppt

3. Lesson Objectives (2) Determine position by compass bearings
Computing speed, time and distance
Make a dead-reckoning plot
Use of tide tables
Electronic navigation
SSSpptChpt12Navigation ppt

4. Nautical Chart Features
Projections-How to show round earth on flat surface
Mercator Projection-a cylinder
Distorts Northern latitudes
Lat/Long scales are different
Best for plotting over long distances
SSSpptChpt12Navigation ppt
Reprinted with permission from the Weekend Navigator by Bob Sweet

5. Nautical Chart Features
Projections
Polyconic Projection- uses a cone
Less distortion over small area
Used in waterways such as AIWW
SSSpptChpt12Navigation ppt

6. Nautical Chart Features
5-C Chesapeake Bay :25.000
5-B Chesapeake Bay :80.000
5-A Chesapeake Bay :
Chart Scales
What do all these numbers and symbols mean?
SSSpptChpt12Navigation ppt
Reprinted with permission from How to Read a Nautical Chart by Nigel Calder

7. Nautical Chart Features
Every chart has a:
Title Block
Type of projection
Scale
Vertical and horizontal datums
Cautions and Notes
Tide information
References to other sources of information
SSSpptChpt12Navigation ppt
Reprinted with permission from How to Read a Nautical Chart by Nigel Calder

8. SSSpptChpt12Navigation ppt
Reprinted with permission from the Weekend Navigator by Bob Sweet

9. Your Boat’s Compass Features Installation Adjusting
SSSpptChpt12Navigation ppt
Reprinted with permission from the Weekend Navigator by Bob Sweet

10. Fixing Your Position
Latitude-Angular degrees N or S of the Equator, measured 0-90 degrees
Longitude-Angular distance E or W of Prime Meridian in Greenwich England, measured degrees
SSSpptChpt12Navigation ppt

11. Fixing Your Position Parallels of latitude
SSSpptChpt12Navigation ppt

12. Fixing Your Position
Longitude lines
SSSpptChpt12Navigation ppt

13. Fixing Your Position Locating a point on the chart using lat/long
Be very careful reading the scales!
SSSpptChpt12Navigation ppt
Reprinted with permission from the Weekend Navigator by Bob Sweet

14. Fixing Your Position Measuring distance
There are 360 degrees of arc around the earth, so
There are 22,600 minutes of arc around the earth
90 degrees X 60 minutes per degree = 5400 minutes
5400 X 4 = 22,600 minutes = 22,600 miles
22,600 nautical miles = circumference of the earth!
1 minute of arc equals 1 mile of distance
And that’s why we use nautical miles at sea
SSSpptChpt12Navigation ppt

15. Fixing Your Position Plotting Courses Measuring direction
We use a course plotter or:
parallel rules aligned with compass rose
SSSpptChpt12Navigation ppt
Reprinted with permission from the Weekend Navigator by Bob Sweet

16. Two Sources of Compass Error
Variation
Difference in degrees between true and magnetic north
Deviation
Compass error caused by nearby magnetic objects
What is the local variation (see compass rose…)
SSSpptChpt12Navigation ppt

17. Correcting a Compass Reading
True
(T)
+ west
Variation
(V)
- west
Magnetic
(M)
- east
Deviation
(D)
+ east
Compass
(C)
SSSpptChpt12Navigation ppt

18. Finding Your Position Line of position-LOP
FIX-where two or more LOPs cross
Range LOP-Natural or manmade
Bearing LOP-from compass
Circle of position-from radar
SSSpptChpt12Navigation ppt

19. Finding Your Position Fix from two bearings to charted objects
SSSpptChpt12Navigation ppt

20. Finding Your Position
Range LOPs
SSSpptChpt12Navigation ppt

21. Finding Your Position How to get compass bearings:
Hand bearing compass
Binocular compass
Boat’s compass
SSSpptChpt12Navigation ppt
Reprinted with permission from the Weekend Navigator by Bob Sweet

22. Speed – Time – Distance
SSSpptChpt12Navigation ppt

23. Dead Reckoning
SSSpptChpt12Navigation ppt

24. Tides Spring Tides-occur when moon and sun are aligned
Neap Tides-occur when the moon and sun are at right angles relative to earth
SSSpptChpt12Navigation ppt

25. Types of Tides Diurnal Semi-diurnal Mixed
SSSpptChpt12Navigation ppt
Reprinted with permission from the Weekend Navigator by Bob Sweet

26. Electronic Navigation
GPS-Global Positioning System
DGPS-Digital GPS-better
WAAS-Wide Area Augmentation System-best
Electronic Charts-2 types:
Raster–“dumb” data—just pixels-a digital “photo” of a chart, all the data, all the time
Smaller file sizes
Vector–Smart data—each data type is encoded and layered
Aids to navigation, topography, hydrography, etc. in separate layers
Larger file sizes
SSSpptChpt12Navigation ppt

27. GPS/Chartplotters SSSpptChpt12Navigation040609.ppt
Reprinted with permission from Using GPS: A Captain’s Quick Guide by Bob Sweet

28.
SSSpptChpt12Navigation ppt