Transcript United States Power Squadrons ® Advanced Piloting Course Chapter 5 Positioning Techniques Positioning for the Advanced Pilot  Staying in touch is imperative • With the.

United States Power Squadrons
®
Advanced Piloting Course
Chapter 5
Positioning Techniques
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 2
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
Slide 3
Plotting GPS Position
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Slide 5
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 6
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
Slide 7
Position by Bearing & Distance
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Slide 9
Plotting the GPS Bearing
Slide 10
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
some plotters have an
index arm with a
variation scale
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protractor scale
Slide 11
Using Plotter with Variation Scale
180° up
center on
waypoint
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next, plot
distance to waypoint
Slide 12
Exercise 5-1 – Plot Bearing & Distance
 Get out Bowditch Bay chart
 Plot a fix using bearing & distance
SOLUTION
Slide 13
Solution to Exercise 5-1
Slide 14
Using Bearings to Waypoints
©2003, “GPS for Mariners”, Reprinted with Permission
Slide 15
Using Distances to Waypoints
©2003, “GPS for Mariners”, Reprinted with Permission
Slide 16
Using Grid Line Crossing
©2003, “GPS for Mariners”, Reprinted with Permission
Slide 17
Using the Compass Rose as Waypoint
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Slide 18
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
Slide 19
Using Radar to Avoid Danger
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Slide 20
Using Radar for Distance Off
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Slide 21
Exercise 5-2 – Radar distance off
 Get out Bowditch Bay chart
 Radar VRM indicates distance off
• Can be used to provide an LOP
Slide 22
Solution to Exercise 5-2
Exercise 5-2
Radar
Distance
Off
Slide 23
Positioning with Seaman’s Eye
 Using Ranges
 Avoiding Collisions
Slide 24
Formal Range
Slide 26
Range Pictures
Slide 28
Using a Range to Check your Compass
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Slide 29
Convenient Range to Harbor
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Slide 30
Plotting Underway using GPS
 Normal plotting
 Converting to Dead Reckoning
Slide 37
Plotting GPS Fixes Underway
GPS Fix
Visual bearing
GPS Fix
Visual bearing
GPS Fix
Visual on buoy
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Slide 38
Transition to Dead Reckoning
Bearing and DR
Position as a check
GPS Fix
Bearing doesn’t match
Fix from bearings
Proceed by Dead Reckoning
GPS Fix
Visual on buoy
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Slide 39
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
Slide 40
Graphical Definition of Data Fields
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Slide 41
Situation – GPS data fields
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Slide 42
Using Crosstrack Error to stay safe
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Slide 43
Optimizing Progress while Tacking
 Challenge for Sailors
1. Selecting the best heading
Considering 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…
Slide 44
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!
© 2004 “The Weekend Navigator”
Slide 45
Using GPS Velocity Made Good - 1
Boat Speed
– determined by polar diagram
VMG
Wind
Destination
– determined by vectors
GPS
– provides real-time indication
of VMG
Slide 46
Using GPS Velocity Made Good - 2
Boat Speed
– higher in this direction
VMG
– higher even though pointed
farther from destination
Destination
GPS
– provides real-time indication
of VMG
Slide 47
Using GPS Velocity Made Good - 3
Boat Speed
– still higher in this direction
VMG
– lower due to geometry
Destination
GPS
– provides real-time indication
of VMG
Slide 48
Using VMG - heading
steer for
max VMG
VMG
45°
50°
boat heading from wind
55°
Slide 49
Using VMG – sail set
adjust for
max VMG
VMG
too loose
too tight
sail set
Slide 50
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
Slide 53
Final Tack – Bearing to Mark
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Slide 54
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 55
Exercise 5-3 Conditions
075°M
Slide 56
Possible Solutions to Exercise 5-3
Slide 57
Questions ? … Comments
Slide 58