Advanced Piloting Course Chapter 5 Positioning Techniques United States Power Squadrons ®
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Transcript of Advanced Piloting Course Chapter 5 Positioning Techniques United States Power Squadrons ®
Advanced Piloting Course
Chapter 5Positioning Techniques
United States Power Squadrons ®
Slide 2
Positioning for the Advanced Pilot
Staying in touch is imperative
• With the surroundings Constantly looking for navigation aids and
landmarks Reference to the shoreline
• With the chart Awareness of current position
– Plotting GPS position– Comparing Radar position
Checking bearings
• Ready backup Dead reckoning and bearings
Slide 3
Plotting Position
Position provided by GPS• …but the chart tells you where you are (if you plot your position)
Basic technique• Plot latitude and longitude
Watch out for…• Incorrectly read or plot coordinates• Wrong waypoint selected in GPS
8-15© 2004 “The Weekend Navigator” Slide 5
Plotting GPS Position
Slide 6
Disadvantages to Plotting Coordinates
Folded chart• Coordinate scales not visible
Transcription errors• Coordinates are just strings of
numbers
Takes time• May rely on eye or skip entirely
Can be a big mistake!
Slide 7
Other Approaches with GPS?
Plot Bearing & Distance• To a waypoint• Using GPS data fields
Plot Bearings to 2 Waypoints• Using GPS nearest waypoints
Plot Distances to 2 Waypoints• Using GPS nearest waypoints
Plot using Grid Line Crossing• Using GPS coordinates
8-16© 2004 “The Weekend Navigator” Slide 9
Position by Bearing & Distance
Slide 10
Plotting the GPS Bearing
© 2003, R J Sweet, “GPS for Mariners.” Reprinted with permission© 2004 “The Weekend Navigator”
Slide 11
Plotting a Waypoint Bearing
Using a Protractor Plotter
1. Place over waypoint
2. 180° on top
3. Line-up with bearing
4. Adjust for variation
variation scale
protractor scalesome plotters have anindex arm with a variation scale
© 2003, R J Sweet, “GPS for Mariners.” Reprinted with permission© 2004 “The Weekend Navigator”
Slide 12
Using Plotter with Variation Scale
180° up
center onwaypoint
next, plot distance to waypoint
Slide 13
Exercise 5-1 – Plot Bearing & Distance
Get out Bowditch Bay chart
Plot a fix using bearing & distance
SOLUTION
Slide 14
Solution to Exercise 5-1
Slide 15
Using Bearings to Waypoints
©2003, “GPS for Mariners”, Reprinted with Permission
Slide 16
Using Distances to Waypoints
©2003, “GPS for Mariners”, Reprinted with Permission
Slide 17
Using Grid Line Crossing
©2003, “GPS for Mariners”, Reprinted with Permission
© 2003, R J Sweet, “GPS for Mariners.” Reprinted with permission© 2004 “The Weekend Navigator”
Slide 18
Using the Compass Rose as Waypoint
Slide 19
Position with the aid of Radar
Radar can support position• Fixes can be derived from point targets
Buoys– Challenge is to identify the proper return as buoy
Points of land or unique features
• Position can be deduced from shoreline echoes Shoreline echoes
– Identifiable profile – approximate position (seaman’s eye)– Relatively flat shoreline – approximate distance off
© 2003, R J Sweet, “GPS for Mariners.” Reprinted with permission© 2004 “The Weekend Navigator”
Slide 20
Using Radar to Avoid Danger
© 2003, R J Sweet, “GPS for Mariners.” Reprinted with permission© 2004 “The Weekend Navigator”
Slide 21
Using Radar for Distance Off
Slide 22
Exercise 5-2 – Radar distance off
Get out Bowditch Bay chart
Radar VRM indicates distance off• Can be used to provide an LOP
Slide 23
Solution to Exercise 5-2
Exercise 5-2
RadarDistance
Off
Slide 24
Positioning with Seaman’s Eye
Using Ranges
Avoiding Collisions
Slide 26
Formal Range
Slide 28
Range Pictures
© 2003, R J Sweet, “GPS for Mariners.” Reprinted with permission© 2004 “The Weekend Navigator”
Slide 29
Using a Range to Check your Compass
© 2003, R J Sweet, “GPS for Mariners.” Reprinted with permission© 2004 “The Weekend Navigator”
Slide 30
Convenient Range to Harbor
Slide 37
Plotting Underway using GPS
Normal plotting
Converting to Dead Reckoning
© 2003, R J Sweet, “GPS for Mariners.” Reprinted with permission© 2004 “The Weekend Navigator”
Slide 38
Plotting GPS Fixes Underway
GPS FixVisual on buoy
GPS FixVisual bearing
GPS FixVisual bearing
© 2003, R J Sweet, “GPS for Mariners.” Reprinted with permission© 2004 “The Weekend Navigator”
Slide 39
Transition to Dead Reckoning
GPS FixVisual on buoy
GPS FixBearing doesn’t match
Fix from bearingsProceed by Dead Reckoning
Bearing and DRPosition as a check
Slide 40
Monitoring Position while Sailing
Challenge• Sailing into the wind• Powering into the waves
Requires tacking rather than direct path
• Staying safe• Monitoring progress
Use GPS• Data fields
Course, Track, Bearing Crosstrack Error (XTE) VMG (velocity made good)
– Optimize progress and sails
© 2003, R J Sweet, “GPS for Mariners.” Reprinted with permission© 2004 “The Weekend Navigator”
Slide 41
Graphical Definition of Data Fields
© 2003, R J Sweet, “GPS for Mariners.” Reprinted with permission© 2004 “The Weekend Navigator”
Slide 42
Situation – GPS data fields
© 2003, R J Sweet, “GPS for Mariners.” Reprinted with permission© 2004 “The Weekend Navigator”
Slide 43
Using Crosstrack Error to stay safe
Slide 44
Optimizing Progress while Tacking
Challenge for Sailors
1. Selecting the best headingConsidering boat performance relative to the
wind
2. Tuning the sails to the wind
Racers use polar diagrams
You can use your GPS, here’s how…
© 2003, R J Sweet, “GPS for Mariners.” Reprinted with permission© 2004 “The Weekend Navigator”
Slide 45
Polar Diagram for Sailboat
As close as you can sail with this boat
You will go faster with this heading, but will it get you there faster?
You’re sailing farther away from your destination!
BOAT SPEED 7 kn
Slide 46
Using GPS Velocity Made Good - 1
Destination
Boat Speed – determined by polar diagram
VMG – determined by vectors
GPS – provides real-time indication of VMG
Wind
Slide 47
Using GPS Velocity Made Good - 2
Destination
Boat Speed – higher in this direction
VMG – higher even though pointed farther from destination
GPS – provides real-time indication of VMG
Slide 48
Using GPS Velocity Made Good - 3
Destination
Boat Speed – still higher in this direction
VMG – lower due to geometry
GPS – provides real-time indication of VMG
Slide 49
Using VMG - heading
VMG
boat heading from wind
45° 50° 55°
steer for max VMG
Slide 50
Using VMG – sail set
VMG
sail set
too loose too tight
adjust for max VMG
Slide 53
Using GPS VMG
Don’t need theory• No polar diagrams
Adjust for maximum VMG• Adjust heading• Adjust sails
Results• Optimum pointing and sail configuration• Real time adaptation to changes in
winds
© 2003, R J Sweet, “GPS for Mariners.” Reprinted with permission© 2004 “The Weekend Navigator”
Slide 54
Final Tack – Bearing to Mark
Slide 55
Exercise 5-3 – Route Planning
Use Bowditch Bay chart• Homework
Select a route for sailing into the wind
Make real-time on the water decisions
Sail from R N “14” on main channel To RG “D” on NE Bowditch Bay
Slide 56
Exercise 5-3 Conditions
075°M
Slide 57
Possible Solutions to Exercise 5-3
Slide 58
Questions ? … Comments