Advanced Piloting Course Chapter 4 Avoidance Techniques United States Power Squadrons ®

Slide 2 Navigation from a different Perspective  What you have learned: Point-to-point navigation  Primary technique in Piloting & AP  Pre-qualify the path, follow the path  Alternative & complementary approach Navigating to avoid  Avoid shallow water  Avoid hazards  Avoid restricted areas Chapter 4  Danger Bearings, Circles  Avoidance Techniques

Slide 3 First Step  Determining what to avoid Examine chart for region of interest Identify:  Region for boating »Limits of latitude and longitude »Harbors or bays  Hazards »Rocks »Obstacles »Shallow water  Charted, visible reference points »Navigation aids »Landmarks

© 2004 “The Weekend Navigator” Slide 4 Determining the Avoidance Area

Slide 5 Danger Bearings  Intent: By monitoring bearing to a landmark  Stay away from danger  SKILL Plotting and Labeling Danger Bearings Monitoring the bearing on the water

Slide 6 Constructing a Danger Bearing

Slide 7 Constructing a Danger Bearing

Slide 8 Constructing a Danger Bearing

Slide 9 Constructing a Danger Bearing

Slide 10 Constructing a Danger Bearing

Slide 11 Constructing a Danger Bearing

Slide 12 Constructing a Danger Bearing

Slide 13 Constructing a Danger Bearing

Slide 14 Constructing a Danger Bearing

Slide 15 Constructing a Danger Bearing

Slide 16 Constructing a Danger Bearing

Slide 17 Constructing a Danger Bearing

Slide 18 Monitoring Position  Danger Bearings Visual bearings  Hand-bearing compass  Monitor bearing to landmark GPS bearings  Enter landmark as waypoint  Monitor GPS bearing to landmark

© 2004 “The Weekend Navigator” Slide 19 Using Danger Bearings

Slide 20 Danger Sector

Slide 21 Exercise 4-1 – Danger Bearing  Take out Bowditch Bay chart  Plot and label danger bearing

Slide 22 Solution to Exercise 4-1

Slide 23 Crosstrack Error  Feature in GPS Data Field  Indicates deviation from course line  Left or Right of intended course  Distance in feet or nautical miles Alarm  An alarm can be set  Sounds if exceed crosstrack error

Slide 24 Crosstrack Error  Uses Stay close to course line Boat freely within lateral limits  Sailing

Slide 25 Crosstrack Error – Avoid Hazards

© 2004 “The Weekend Navigator” Slide 26 Determining an Avoidance Region rhumb line alarm upon exit

© 2004 “The Weekend Navigator” Slide 27 Using Crosstrack Error

Slide 28 Exercise 4-2  Using Bowditch Bay chart  Plot & label – Crosstrack Error

Slide 29 Solution to Exercise 4-2

Slide 30 Danger Circles  Danger circles  Similar concept to danger bearing  Danger is within or outside of the circle  Measuring a danger circle GPS  Anchor watch (stay within the circle)  Avoidance waypoint (stay outside the circle)  Alarmed Radar  Monitor radius to an object  Guard zone –Alarmed

© 2004 “The Weekend Navigator” Slide 31 Avoidance Waypoint

© 2004 “The Weekend Navigator” Slide 32 Using Danger Circles

Slide 33 Danger Circles

Slide 34 Exercise 4-3 – Danger Circles  Take out Bowditch Bay chart  Plot and label – danger circle Use radar VRM

Slide 35 Solution to Exercise 4-3

Slide 36 Putting it all Together

Slide 37 Danger Bearing - 1

Slide 38 Danger Bearing - 2

Slide 39 Danger Bearings Define Entrance

Slide 40 Alternative – GPS Bearing + XTE

Slide 41 Danger Circles

Slide 42 Putting it all Together

Slide 43 Other Avoidance Techniques  GPS Mark boundaries  Linear boundary (artificial buoys)  Cardinal boundary (N-S-E-W of danger)  Digital Chart Navigation Computer  Create any shape for a danger area  Tied to an alarm  Can select exit or entrance alarm –Alarm when leave (e.g., anchor watch) –Alarm when enter (e.g., danger area)

© 2004 “The Weekend Navigator” Slide 44 Adding Waypoints to Define Shallows

© 2004 “The Weekend Navigator” Slide 45 Alarms on a Chart Screen

© 2004 “The Weekend Navigator” Slide 46 Safe Area Alarm

Slide 47 Questions ? … Comments