United States Power Squadrons

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United States Power Squadrons Boating Course
Section 7 Piloting Plotting a Course Version
5.0 - 1/2006
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Definitions

• Navigation
• The science of moving a boat in a safe and
  efficient manner.
• Piloting
• A part of navigation using landmarks,
  navigational aids, and soundings as primary tools.

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Rectangular Course Plotter Used throughout USPS
courses

1. 4x15 Transparent base
2. Parallel lines for alignment
3. Protractor scale for measurement

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Various Styles of Dividers
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A Chart Compass Rose
Variation is found in the center of the compass
rose
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Why Rules for Chart Work?

• Good habits will reduce errors
• Mistakes are easier to find
• Information is clear for future use
• Other boaters can follow your work
• You know you are in Safe Water

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Accuracy Standards

• Angle - Nearest Whole Degree - 214 º
• Distance - Nearest 1/10 of a mile - 6.5 nm
• Speed - Nearest 1/10 of a knot - 4.3 kn
• Time - Nearest whole minute - 1343

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Class Exercise
Plot a Course

• On the Bowditch Bay chart, plot a course
• From G C 1 off Chapman Point
• To RG D Gong on the upper right side of the
  chart

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Bowditch Bay Practice Chart
RG "D"
G C "1"
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How ToDraw A Course Line Using
The Course Plotter
RG "D"

• C "1"

Bowditch Bay Chart
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Bowditch Bay Practice Chart
1
Lay edge of the Course Plotter between the two
nav aids
2
Using the Course Plotter as a straight edge, draw
the course line
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How ToDetermine Course Heading Using
The Course Plotter

• Two Methods
• Using Plotter Latitude grid lines
• Using Plotter Longitude grid lines

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Plotting Tools
000
Straight edge course line
270
090
180
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Using Longitude Grid Line
Read 067º on outer scales (scales read
right to left)
Slide straight edge along course line
Destination Waypoint
align bulls-eye with grid line
Starting Waypoint
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Using Latitude Grid Line
Read 157º / 337º on outer scales (scales
read right to left)
Latitude Grid Line Yields Wrong Quadrant
Slide straight edge along course line
Destination Waypoint
align bulls-eye with grid line
Starting Waypoint
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Using Latitude Grid Line
Read 140º / 320º on inner scales (scales
read right to left)
EXAMPLE 2 (new course) Latitude Grid Line Yields
Proper Quadrant
Slide straight edge along course line
Starting Waypoint
align bulls-eye with grid line
Destination Waypoint
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Labeling A Course Line
RG "D"
C 067
C "1"
Course 067 true
Place the true course direction near the
beginning of the course
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Bowditch Bay Practice Chart
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Class Exercise
Using Maptechs Chart Navigator A2B function,
determine the reciprocal course in the prior
exercise.
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Determine the Coursevia Chart Navigator
1. Select A2B Tool
2. Move cursor to 1st waypoint, click
3. Move cursor to 2nd waypoint, click
4. Cursor over 1st or 2nd waypoint, right click
5. Click Properties
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Labeling A Course Line
reciprocal 067 180 247
RG "D"
C 247
C "1"
Course 247 true
Place the true course direction near the
beginning of the course
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Bowditch Bay Practice Chart
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Conclusion
1. Estimate the course (at least to 0-90,
90-180, etc). 2. Put a pencil or divider tip on
one of the course points. 3. Bring the top edge
of the plotter around so it goes between the two
points. 4. Slide the plotter along the course
line until the plotter bullseye is on a
horizontal or vertical grid line. (Having the
pencil or divider on one of the course points
makes it easier to slide the plotter while
keeping it aligned with the course line.) 5.
Look at the four possible course readings, pick
the one that fits your estimate of the course.
(this, along with step 1, eliminates the need for
remembering whether the inner graduations are for
use with a meridian or parallel)
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United States Power Squadrons Boating Course
END Section 7