Piloting Course - Outline
The total course is presented in 10 sessions as follows:
Session 1
Chapter 1 Introduction to Navigation - with class exercises
Session 2
Chapter 2 Tools of Piloting - with class exercises
Session 3
Chapter 3 Plotting & Planning Techniques - through Bearings with class
exercises
Session 4
Chapter 3 Plotting & Planning Techniques - Relative Bearings, Pre-planning
Safe Paths to end with class exercises
Session 5
Chapter 4 On The Water – with class exercises
Session 6
Chapter 5 Beginning GPS Navigation –using GPS as a navigation tool
Session 7
Chapter 5 Beginning GPS Navigation -with class exercises, start cruise
Session 8
Chapter 6 Monitoring Progress – with class exercises, continue cruise
Session 9
Chapter 7 Manual Piloting – with class exercises, continue cruise
Session 10
Chapter 8 Review and hand out open book exam
Reference Text: “The Weekend Navigator” McGraw-Hill, pub 2004 [WN]
Chapter 2 – What is Navigation?
Chapter 3 – Fundamentals of Waypoint Navigation
Chapter 4 – The Tools of Navigation
Chapter 5 – Planning with GPS and Charts
Chapter 6 - Planning with Digital Charts
Chapter 8 – Navigating with GPS
Chapter 10 – Checking your Navigation
Chapter 11 – Eye of the Mariner
Chapter 12 – What to do if the GPS Quits
Course Highlights:



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Piloting emphasizes safe basic navigating using GPS and charts for recreational boaters
The course makes extensive use of exercises starting with the first session, building skills
paralleling instructional material
Instructor demonstrations of each charting task should be presented using the digital charts.
Students pass with skills and knowledge adequate for:
1. Safe navigation in local waters using GPS and charts
2. Beginning plotting skills required for taking the AP course
Safe Navigation is understood to be the demonstrated ability to:
1. Identify and understand the significance of all information on a nautical chart
whether paper or electronic.
2. Prepare and pre qualifying an intended course/route/path, prior to getting underway,
using GPS for identifying desired positions (waypoints) and plotting waypoints on a
chart.
3. Monitor and keep track of progress along intended course while underway.
4. Know where errors in accuracy of GPS and plotting may occur and methods for
identifying, checking and correcting them.
5. Addition of skills of “Seaman’s Eye” to stay in touch between formal steps.
Recommended
1. That students have a computer (but not a requirement of the course), and a calculator
2. That Squadrons offer the GPS Seminar afterward (optional for those who feel they
need more on GPS) to reinforce using the GPS (could be open to public, but
recommend offering to Piloting students at no extra charge), teach with laptop and
projector, invest in discount software
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Piloting Course - Outline
Chapter 1 – Introduction to Navigation (1 session)
1.
2.
Basic Concepts in Coastal and Inland navigation (piloting)
a. Define Piloting
1) Navigation with the aid of landmarks and navigation aids
1. Limited to these areas with visible landmarks and aids
2) Introduction of why basic piloting skills are necessary
1. Provides answers to:
a. Where am I
b. How do I get to where I want to go
2. Need skills to:
a. Navigate with Electronic Tools
b. Check the tools
c. Navigate when they aren’t working
b. Overview of basic concepts
1) Line of Motion (Course)
2) Line of Position (Bearing)
3) Fix
1. Adjacent to a known location
2. Intersecting Bearings (LOPs)
3. GPS [must understand Latitude & Longitude]
c. Define: Seaman’s Eye
1) Part of staying in touch with your surroundings
2) Seasoned mariners have the experience and can rely on Seaman’s Eye to a
greater extent than should new boaters
3) Not a replacement for regular fixes
4) Used between formal steps as a backup
5) ‘Tips’ which will be given throughout course
The use of basic piloting skills to get the most from your GPS
a. What is a Chart?
1) Local accurate scaled representation of water, shoreline
1. Course lines reflect: Direction, Distance
2. Scale is a ratio to the real world
2) Position reflected in a set of coordinates
1. Frame of reference
b. Plotting Tools [Includes demonstrating and using these tools in class]
1) Plotters
1. USPS Rectangular Plotter
2. Parallel Rules (various types)
3. Protractor Arm Plotter
4. triangles – [referred to in an appendix IM approach]
2) Dividers
3) Plotting Techniques [overview plotting accuracy and chart tools]
1. Pencils – fine point, medium softness
2. Erasers
3. Plotting accuracy
c. Concept of Latitude and Longitude [beginning of working with charts]
1) Details of Latitude and Longitude Scales
2) Measuring the Coordinates of a Charted Object
3) Plotting the Coordinates of a GPS Reported Position
EXERCISE 1-1:
Using a tear-out blank chart (just scales and grid, and sample
points, no features) Measure the Latitudes and Longitudes of
sample points
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Piloting Course - Outline
d.
Concept of Course and Distance
1) Measuring Course
2) Drawing a Course
3) Measuring Distance
1. Nautical Miles
2. Latitude Scale
4) Labeling courses
EXERCISE 1-2:
Using same tear-out blank chart, draw course lines between
sample points, measure course direction and distance, label
courses
Chapter 2 – Tools of Piloting (1 session)
1.
2.
Charts [Reading, understanding, and working with charts and related publications in
order to plan safe paths]
a. Have Charts On Board and know how to use them
b. Chart Characteristics
1) Coordinate System – Reference
1. Datum – WGS-84
2) Title Block
1. Scale
2. Depth
c. Chart Features – [demonstrate all on Bowdich Bay using Chart CD, students
follow on paper Bowditch Bay]]
1) Colors change at fathom line
2) Contours fathom and feet
3) Soundings
4) Bottom
5) Hazards
1. Rocks
2. Wrecks
3. Covered, covering [at high tide]
d. Sources of Charts
1) NOAA and Hydrographic Offices
2) Commercial
3) Digital
1. CD-ROM – raster chart (pictures) of all charts in a given region
2. Chip – used in chartplotters (vector) of similar region
Aids to navigation and chart symbology
a. System of Aids to Navigation (review)
1) Buoys
2) Beacons
EXERCISE 2-1:
3.
Using Bowditch Bay, measure Latitude and Longitude of selected
navigation aids, draw courses, measure and label. After students
complete exercise, instructor can demonstrate solutions using USPS
Digital Chart CD
Introduction to using GPS as the primary positioning sensor and a quick overview of how
to use it
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a.
b.
c.
d.
4.
GPS provides position
1) A 3-D position in Space
2) Associated with a reference system on Earth
3) GPS tells position but nothing about what is at or near that location
GPS computes course and speed over ground by your change in position
GPS computes bearing and distance to a selected stored location (waypoint)
You should use GPS extensively in good weather to get a feel for how it works
and confidence in your skills, then in bad weather you can use it more confidently
EXERCISE 2-2:
Plot GPS coordinates on Bowditch Bay chart
EXERCISE 2-3:
Identify chart features
Mariner’s Compass [New Standard – We will explain use of both True and Magnetic for
Courses and Bearings, for the purposes of this course, [for the recreational boater], we
prefer and will use Magnetic because that is the information mariners’ compasses
provide, and for the labeling standard]
a. Appreciation of the mariner’s compass as the primary tool for steering a course
1) Importance of the ship’s compass
b. Magnetic North vs. Chart (True) North
1) Understanding and using Magnetic variation
1. Compass Rose
2) Converting between True and Magnetic North
1. TVM
3) What GPS tells you
1. Setting the GPS to Magnetic reference
c. Techniques to Measure Magnetic Courses and Bearings
1) Parallel Rules and Compass Rose
2) Rectangular Plotter and TVM
d. Plotting and Labeling Courses
EXERCISE 2-4:
Reading and Plotting Magnetic Courses, plot magnetic courses
with computer and digital charts do TVM conversions, done in
class
Chapter 3 – Plotting & Planning Techniques (2 sessions)
[Exercise for every concept using Bowditch Bay Chart]
1. Overview of Basic Plotting Techniques [intro to what is covered in this chapter]
a. Dead Reckoning
b. Bearings
1) Fixes
2) Positioning Techniques
1. Ranges
2. Relative Bearings
3. Seaman’s Eye
2. Dead Reckoning
a. Position based on Direction, Speed and Distance
1) Start from known location - fix
2) Direction of Motion (DR Track) based on Steered Course
1. DR Track is the line that you draw
2. Labeling
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Piloting Course - Outline
3)
b.
c.
Distance based on
1. Direct reading device – distance log
2. Calculation based on Speed and Time
a. Distance=Speed x Time
i. D (nm) = S (nm/hr) x T (hr)
ii. Need to use ‘60’ for time in minutes
1. 60D = S x T
Navigating
1) Maintain DR Plot
1. Mark Course Direction and Speed
2. Calculate DR periodically*
a. Using 60D=ST and dividers
Overview of Accuracy [highlight, no details]
1) Need to maintain course and speed
2) Impacted by winds and currents
EXERCISE 3-1:
Plotting and labeling DRs on Bowditch Bay
*[New Standard: DR positions and GPS fixes will be plotted on a chart on a regular
basis. The time interval will depend upon the speed of the boat and prevailing conditions,
nominally hourly. You as navigator are responsible for the safety of your crew and boat.
Labeling standards: Speed knots (nm) to nearest 2 significant digits (e,g, 4.8, 12, 23),
Time to nearest minute, Distance to tenths of a nautical (statute) mile] Demo graphic that
shows larger ‘circle of uncertainty’ as DR progresses without an intermediate fix.
3.
Bearings
a. Line of Position based on Direction to Visible Charted Landmarks
1) Attributes of a LOP
2) Labeling: Time on top, Magnetic bearing below (xxx M)
b. Methods for Taking Bearings
1) Compass – hand-bearing
2) Relative
c. Compass Bearings
1) Measure angle to Landmark
1. Hand-bearing Compass
a. Everyone should have one
2. Ship’s Compass
a. Bow Bearing
2) Plotting Bearing
1. Plot, label Magnetic
2. Construct Line Toward Landmark [draw on the line from the
boat to the landmark a graphic]
3) Where are you?
1. Location on LOP
EXERCISE 3-2:
d.
Fix
1)
Plot and label Bearings
Two Bearings
1. Two LOPs
2. Fix at Intersection
EXERCISE 3-3:
Plot bearings, label and label fix
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2)
Three or More Bearings
1. Confirmation
2. Intersection Triangle (Cocked Hat)
BREAK FOR THIS CHAPTER
e.
Relative Bearings relevant to seaman’s eye
1) Based on Orientation Relative to Boat
1. Based on Position with respect to the Bow
2) Typical Relative Bearings
1. Bow Bearings [sight on centerline of boat]
2. Beam Bearings
3. Collision Bearings
3) Plotting
1. MB = RB + MH
EXERCISE 3-4:
4.
Plot and label relative bearings (bow & beam bearings)
Other Positioning Techniques
a. Ranges
1) Definition
1. Range from any two charted landmarks
2. Pre-plotted vs. on the water
3. Based on visual alignment
2) Navigation Ranges
1. Designed for channels
2. Maintain Alignment
3) Selecting Your Own Ranges
1. Selecting Landmarks
EXERCISE 3-5:
Measure ranges, create your own ranges, plot and label
** [Seaman’s Eye excerpts can be highlighted as ‘TIP’]
b. Seaman’s Eye
1) Bow and Beam Bearings
1. Sighting by Eye
2. Turning the Bow
3. Passing by on the Beam
5.
6.
Concept of Pre-planning [Intent to pre-qualify the path before taking it]
a. Allow sufficient width for error
1) use ±0.1 nm as standard in normal conditions [smallest increment on
latitude scale]
b. Navigation Aids provide visible reference
c. Plot paths between Navigation Aids whenever possible
d. Check the paths
e. Planned paths (legs) have starting and ending points (waypoints)
f. That information is plotted on the chart and stored in the GPS
1) Waypoint Navigation
Criteria for a Safe Course
a
Determining Safe Depth
1) Difference between sounding, depth, draft and clearance
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Piloting Course - Outline
2)
b.
c.
Understanding Chart Datum
1. MLW, MLLW, MHW…
2. **wave heights in relation to depth in AP**
Avoiding Hazards
1) Identify any hazards along or near path
Working around obstacles
1) Build a route (sequence of legs) around obstacles
Chapter 4 – On-the-Water (1 session)
1.
2.
3.
4.
The responsibilities of the skipper
a. Explain that as skipper it is up to you to decide the proper navigation
b. The safety of your crew and boat is your responsibility
c. The following chapters will put into practice navigation using the plans made
using techniques learned
The core method
a. GPS as the position sensor and bearing reference to waypoints
b. Ship’s Compass for Steering
c. Seaman’s Eye to keep in touch with your surroundings
1) Use between formal steps, not used in lieu of navigation
d. Hand-bearing Compass for taking Bearings
e. GPS Position will be plotted (and checked) at regular intervals*
Recognizing aids to navigation and other charted objects on the water and relating to the
charts and GPS
a. Day, Night, Limited Visibility
Using a Compass in Navigating
a.
The mariner’s compass: performance and characteristics
1) Compass Attributes
1. Characteristics of a Quality Compass
2. Selecting a Compass
a. Consider upgrading
b. Most important navigation tool on your boat
b. The importance of compensation, and adjustment for any resultant deviation
1) Deviation
1. Deviation is based on the boat not the environment
2. It changes based on the heading of the boat
2) Compensation
1. Avoidable errors vs. compensatable errors
2. Deviation can be minimized to a reasonable residual amount in
most compasses
3. Professional compensation strongly recommended
4. Compensating the Compass Yourself
a. Not for most people – can make it worse
b. Reference to Learning Guide
5. Table of residual deviation – used for navigation
a. Assume for this course have a compensated compass
b. More important when traveling on longer legs
i. Either adjust for D, or
ii. Take more fixes
c. Conversion from true to magnetic to compass direction, and the reverse process
1) TVMDC
1. Explain TVMDC Diagram
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Piloting Course - Outline
d.
e.
f.
6.
2. Explain use of “West is Best” and “East is Least” for True to
Compass
Practical Use of the Compass and dealing with Deviation
1) Practical accuracy of a recreational ship compass [New Standard: most
compasses are graduated in 5° increments and can be read to about 2-3°
- therefore, any compass compensated to within 3° will not require
calculation for D – there will be homework but no examination based on
adjusting for D, Deviation and TVMDC will be reintroduced in AP where
the cruises are longer and the accuracy requirement is greater]
Use of the chart’s Compass Rose
1) Extremely valuable tool
2) Provides Chart Variation and Change in Variation
3) Source of Magnetic directions using parallel rules
4) Provides a ‘sanity check’ as a backup
The fluxgate compass
1) Configuration
1. Sensor
2. Processor
3. Display
2) Performance and Characteristics
1. High accuracy
2. Self-Compensation
3) Selection
1. Location considerations
EXERCISE 4-1:
Correcting for Variation using TVMDC
EXERCISE 4-2:
Plotting with Rectangular Course Plotter and Parallel Rules
using Compass Rose
Planning a Day Cruise on Bowditch Bay (in class)
a. Present the objective of your cruise
b. Work through the planning issues in class
c. All students end with the same plan
d. Homework: Navigate the 1st part of the one day cruise
1) Instructions throw in challenges
1. Off-course
2. GPS Fails
Chapter 5 – Beginning GPS Navigation (2 sessions)
1. Using The GPS As A Navigation Tool
a. What the GPS can do
1) Provides position in latitude and longitude
2) Provides a course to steer if waypoints are used
3) Provides estimated arrival time at destination
b. What GPS cannot do
1) Cannot warn of hazards
2) Cannot determine water depth
2. Receiver Keyboard Functions
a. Power Button
b. The Cursor Key – usually a four-position thumbkey – perform same function as a
computer mouse
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Piloting Course - Outline
c. The Enter Button (MARK)
d. The Menu Button
e. The Quit Button – much like the “Esc” key on a computer
f. The GOTO Button (Nav)
g. The Page Button
h. The Mark Button
i. The MOB Button
3. Typical GPS Screens
a. Satellite Screen – quality of fix, is satellite coverage okay?
b. Position Screen – coordinates, other useful information
c. Map Screen – usually not a chart, only waypoints
1) Must plot position on a paper chart at regular intervals
1. [New Standard – You are the navigator, you are responsible - it
is essential that you regularly plot GPS position and time on your
chart so that you can go back to that last reference in the event of
a failure, generally that should be done approximately every
hour, but if conditions (risk, visibility, etc.) warrant, that should
be done more frequently; also note time that you reached
waypoints]
2) Shows waypoints within field of view (zoom)
3) Shows current location
4) Shows active course or route (discussed later in this chapter)
5) Cursor position coordinates and relative position to current location
d. Highway Screen
1) 3-D Highway
2) Shows position vis-à-vis active leg (discussed later in this chapter)
e. Compass Screen
1) Shows direction to active waypoint and direction of current motion
4.
Entering Waypoints in the GPS
f. Getting Waypoint Coordinates
1) Measure L, Lo on Chart (Ch 1)
1. Paper
2. Digital
2) Pre-plotted on Charts
3) Waypoint Books
4) Marks
g. Opportunities for error
1) Incorrectly read waypoint coordinates from the chart
2) Incorrectly enter coordinates into the GPS
3) Incorrectly select the proper waypoint for navigation
**
TIP – Naming Waypoints
h. Naming Waypoints for Easy Identification
1) Mark same names on Chart
1. examples
i. Entering Landmarks as Waypoints
1) Using visible bearings to compare with the GPS
2) Anticipating potential landmarks and storing their coordinates
5. What GPS Does when you Select and Activate a Waypoint
a. GPS Computes Bearing and Distance
1) From your current location to the waypoint
2) GPS does not qualify that path
1. Recommend starting on a pre-qualified path, otherwise
2. Must plot current position and qualify the path
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Piloting Course - Outline
3)
6.
**
7.
Plots leg on Map Screen, representative highway on Highway Screen,
arrow on Compass Screen and Bearing and Distance to Waypoint in data
fields on all relevant screens
Constructing Routes
a. Sequence of stored Waypoints
b. Computes Bearings and Distances for each leg
TIP – Checking Waypoints and Routes
Checking Waypoints and Routes Stored in the GPS
a. Compare plotted course angles and leg distances on the chart with the courses and
bearings computed by the GPS route reveals mistakes in entering waypoints
START:
Part 1 of cruise
BREAK FOR THIS CHAPTER
8.
Activating a Waypoint for Navigation
a. Where are you?
1) Current Location at one end of a pre-qualified path
1. Select the waypoint at the other end
2) Some other Location
1. Plot your current location on a chart
2. Plot the course to the desired waypoint
a. Qualify the path
b. Navigating Waypoint to Waypoint
1) Select the stored waypoint of choice
2) Activate the waypoint
3) Observe the Bearing and Distance calculated and displayed by the GPS
4) Double check that this is reasonable vis-à-vis the chart
1. It is easy to inadvertently select the wrong waypoint
2. Compare bearing and distance, does it match the chart?
c. Using a Route
1) Same criteria regarding the current location vis-à-vis the 1st waypoint
2) The Route activates the first waypoint
9. GPS Calculates and Presents
a. Bearing and Distance to the Active Waypoint
b. Course Line on the Map Screen corresponding to the active leg
1) Also all stored waypoints and data within the field of view
2) If a route is selected, all legs of the route are displayed
c. 3-D highway on the Highway Screen corresponding to the active leg
1) Also all stored waypoints and data within the field of view
2) If a route is selected, all legs of the route are displayed
10. Steer
a. Set heading of Boat toward Waypoint
1) Compass (preferred) or GPS Course (COG or Track)
2) GPS reports Course (to steer) and/or Bearing to Waypoint
11. Course and Speed
a. GPS relies upon motion to determine course and speed
b. GPS is not a compass
1) Compass is attached to the boat – shows heading
1. Direction of the Bow
2) GPS reports Course Over Ground (Track) (COG)[motion of boat]
1. Actual motion on the Earth
c. GPS reports Speed Over Ground (SOG)[motion of boat]
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Piloting Course - Outline
1)
Not speed in the water
1. Impact of currents
12. Intermediate Position
a. GPS Reports
1) Location – Current Coordinates
2) Distance and Bearing
3) Other Data
1. Cross-track Error (or Off-Course)
a. Distance and Direction from Course Line
b. Locating GPS Position on a Chart
1) Using Coordinates
2) Using Bearing and Distance to Active Waypoint
3) Using Bearing and Distance to another Waypoint
4) Updates How to monitor navigation progress using the GPS and plotting
position on the chart
13. Plot Position on Chart [New Standard – Plot Fix and time approximately every hour or
more frequently if conditions warrant]
EXERCISE 5-1:
REVIEW:
START:
Checking waypoints
Part 1 of cruise – starting the cruise – dealing with magnetic courses
Part 2 of Cruise
Chapter 6 – Monitoring Progress (1 session)
1.
2.
On Course with GPS
a. You pre-qualified the path, if you are on course, you have little concern relative to
charted obstacles
b. Map Screen
1) Compare position with plotted course line
1. Zoom in for a better view
2) Position Arrow aligned with the Course Line
c. Highway Screen
1) Current Position in Center of Highway
2) Highway pointed straight ahead
1. Indicates heading toward waypoint
d. Data Fields
1) Course Over Ground (COG or Track) matches Bearing to Waypoint
2) Course Over Ground matches Course (original course direction)
3) Cross-track Error indicates zero or small value (in feet or miles)
Off Course
a. Indicated by a mismatch of any of the above techniques
b. Why?
1) Inattention to helm, cross wind or cross current, wave action
c. If off-course by a small amount
1) As determined by the pre-qualified path width
2) Turn toward original course line and correct heading when back on course
d. If off-course by a large amount
1) Stop and plot position on a chart
2) Check path
1. Path to waypoint clear, proceed on that bearing
2. If not, select a safe path back to the course line
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Piloting Course - Outline
EXERCISE 6-1:
Plot position and determine safe path to destination (multiple
examples)
3.
Staying On Course
a. Use GPS to stay on Course
1) Highway Screen, stay in center of highway
1. Adjust steering until in center of highway with highway straight
ahead
2) Map Screen, arrow on and aligned with course line
3) Data Fields, Course and Bearing Match
b. Boat Heading may differ in a cross current or wind (crab into wind or current)
4. Sequentially navigating to waypoints, one-at-a-time exercising GoTo commands, and
using a route to navigate
5. Concept of Course and Speed over Ground
** TIP – Seaman’s Eye – Bearings and Collision Course
6. Seaman’s Eye
a. Quick Bearings
1) Bow Bearing
1. Bearing to Object matches Boat Heading
2) Beam Bearing
1. Approximate sighting to the side of the boat
a. Estimate when object is abeam
2. Bearing to Object is 90 to Starboard or Port of the Boat Heading
b. Relative Bearings
1) Any bearing taken with respect to the boat is relative
2) Add relative bearing (measured clockwise) to the Boat’s Heading to get
Magnetic Bearing to Object
c. Collision Course
1) Observe Crossing Boat
1. Compare with a spot on your boat
2. If the relative position of the other boat
a. Does not change – collision course
b. Advanced toward the bow – will pass ahead
c. Retards toward the stern – will pass behind
EXERCISE 6-2:
7.
Determine risk of collision (multiple examples)
Checking the GPS
a. Bearings
1) Compare GPS with Bearing to Visible Landmark
1. Use of Handbearing Compass
2. Sight on Landmark (also stored in GPS as a waypoint)
3. GPS Nearest Waypoints
a. Select and observe the current GPS reported bearing to
the same landmark
4. If they match closely (1-2°), the GPS is likely to be working
properly
5. If they don’t match, take additional bearings
b. Multiple Bearings
1. Plot each Bearing on the Chart
2. Two bearings (angle of intersection > 30°) – select intersection
as fix
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c.
3. Three bearings – select center of triangle formed by three lines
as fix
Check Indicates a GPS failure
1) Proceed to Dead Reckoning (See Chapter 8)
2) Use this example to highlight the need for having plotted GPS fixes at
regular intervals
REVIEW:
START:
Part 2 of Cruise – Comparing GPS data with observations
Part 3 of Cruise
Chapter 7 – Manual Piloting (1 session)
1.
Manual Piloting
a. If a position check indicates that the GPS is malfunctioning
1) Immediately determine position
2) Fix on Visible Landmarks, if possible
3) Alternative – deduce position from last known position
b. Dead Reckoning
1) Position based on Direction and Distance
1. Direction based on Steered Course
2. Distance based on
a. Direct reading device – log
b. Calculation based on Speed and Time
i. 60D=ST
c. Navigating
1) Maintain DR Plot
1. Mark Course Direction Distance and Speed
2. Calculate DR nominally every hour*
a. Using 60D=ST and dividers
2) Taking Bearings
1. One Bearing = Estimate
2. Two Simultaneous Bearings = Fix
3) Techniques for estimating ETA and ETE
EXERCISE 7-1:
REVIEW:
START:
Establishing current position based on last known fix, continuing
to destination using DR, checking with bearings, estimating ETA
and ETE
Part 3 of Cruise – Dealing with off-course Bowditch Bay (in class)
Part 4 (final) of Cruise
Chapter 8 – Review and Exam distribution (1 session)
1.
2.
3.
4.
Review Part 4 of Cruise – Establishing position after a GPS failure and proceeding using
Dead Reckoning with updates via bearing
Review Material From Course
Introduction to Advanced Piloting
Hand-out Open Book Exam
Optional – Compare the Cruise using Computer and Digital Charts (not graded)
1. Using CD-ROM with Maptech Chart Navigator and Bowditch Bay
a. Demo Planning on the Fly
2. Compare results with manual cruise
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Optional – Planning with Computer and Digital Charts (not graded) use to reassemble students
when they hand in the open book exams (1 session) [Providing this optional session provides
incentive for students to hand in open book exams on a timely basis]
1. Demonstration of the CD-ROM with Maptech Chart Navigator and Bowditch Bay
a. Features of Software
b. Marking Waypoints
c. Constructing Routes
d. Uploading into GPS
2. The use of digital charts will be demonstrated for re-planning on the fly
Exam
Open Book only - Navigation Exercise using Bowditch Bay
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Appendix – Measuring Compass Deviation with GPS
1. Most boaters steer by compass
a. Important that they understand accuracy of compass
b. Good compass has repeatable readings when pointed in a specific direction
c. Any compass has some deviation
i. If small, can be ignored
ii. If large, must be considered
1. Can be corrected to some degree
a. Recommend a professional
b. Alternative, refer to USPS Compass Adjusting LG
d. This Appendix explains how to determine compass deviation
i. Using GPS as a reference tool
ii. Two approaches
1. Structured set of readings (recommended)
2. Checking as you navigate
a. Over time measure many leg directions
b. Record your deviations and Compass Courses
e. Three approaches to navigating with a compass
i. Have it properly compensated
ii. Note its deviation and correct readings in real time
iii. Note course legs with compass course as well as magnetic or true
2. GPS vs. compass reading
a. GPS provides Course Over Ground (sometimes called ‘TRACK’)
i. COG is the actual motion of the boat over the bottom
ii. Currents and winds will impact COG
b. Compass measures heading of boat
i. Physically oriented with the keel of the boat
3. Tools needed
a. GPS
i. Used as the primary reference
1. Set GPS to read magnetic
2. Auto set for variation
b. Hand-bearing Compass
i. Used to measure local magnetic influences on the boat
c. Ship’s compass
i. Used for steering the boat
1. Properly mounted – aligned with keel
2. Properly located – reasonably far away from magnetic influences
d. Large scale charts for area
i. Plotting tools
ii. Notepads to keep records
4. Preparation
a. Identify visible landmarks nominally oriented to the N, S, E, and/or W of
operating area
i. One will work, more are preferred
b. Identify area of open water
i. Target runs about ¼ nm
c. With boat tied to dock
i. Sight in know charted direction (distant landmark) with handbearing
compass away from the boat – check handbearing compass
ii. On the boat, near the ship’s compass (no closer than 3 ft)– sight to same
landmark
1. Provides sense of local effects on ship’s compass
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Piloting Course - Outline
iii. Use handbearing compass to sight along bow
1. Compare handbearing compass with ship’s compass
iv. Move around boat sighting toward bow, note changes
1. This will give you an idea of regional effects on the boat
2. Useful when taking bearings with handbearing compass at sea
3. Provide an indication of the environment near the ship’s
compass
5. Using the GPS for Structured Deviation Measurements
a. Run courses that are
i. Nominally N-S and E-W
ii. Preferred – steer to landmark
1. Enter landmark in GPS
2. Select starting point using GPS bearing to landmark
a. Direction should be nominally N, S, E, or W
3. Steer to landmark by eye
b. Note difference in Reading between GPS and Compass
i. D is West if Compass reads West of GPS
ii. Average the reading over a run ~ 1/4 mile
1. Run of readings every minute or so
c. Run reciprocal course, run perpendicular course (both ways)
i. Check for both N-S and E-W
d. Is difference in readings consistent?
i. If yes, compass appears to be functioning
1. If errors are less than 3°, make note and plan no corrections
2. If errors are more than 3°, note deviation
3. If errors are more than 10°, check locale of compass for
disruptive materials, consider moving compass
ii. If no, replace compass (if problems not resulting from seas, current or
wind)
e. Are readings in both N-S and E-W directions within 2-3°?
i. If yes, your compass is reasonably close to accurate
1. Regularly check as you navigate (see below)
ii. If no, begin your deviation table
1. Run courses at 45° increments (between N-S and E-W)
a. Note deviations
i. If less than 3°, take no action
ii. If greater than 3°, note deviation
2. Complete your deviation table
6. Conditions for measurements
a. Select relatively flat conditions
i. Eliminate yawing effect of boat
1. Boat constantly changes heading into seas
b. Select areas where current is minimal
i. Quiet section of a bay
ii. Monitor cross track error
1. Steer by sight to landmark, monitor GPS
2. If crosstrack error is minimal, current impact is small
iii. Select different locations that favor various headings
c. Run in both directions
i. Check course and reciprocal
d. If area of significant cross currents
i. Average readings over a period of time
1. Take average difference as deviation
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Piloting Course - Outline
7. Monitoring your Compass as you Navigate
a. More of an Ad Hoc approach, but effective
b. While navigating legs
i. Compare the compass with the GPS
ii. Note deviation
1. Record readings over a period of time
2. Average
iii. Best accuracy when steering by sight to a known landmark
1. Monitor crosstrack error to see if cross wind or current
iv. Note compass courses on chart
1. Average over a period of time
8. Remedial action (summary)
a. Check region around ship’s compass
i. Clear of metallic material
ii. Wires twisted to minimize induced fields
b. Compare effects on boat in various places with handbearing compass (see above)
i. Is ship’s compass in bad location?
ii. Can it be moved?
c. Have the Compass corrected
d. Use an Electronic Compass
e. Note and adjust for Deviation
f. Note and steer to Compass Courses
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