1. Piloting Course Chapter 3 Plotting & Planning Techniques
Piloting Chapter 3
4/24/2017
United States Power Squadrons ®
Piloting Course Chapter 3 Plotting & Planning Techniques
Introduce USPS and what we do
Introduce the Instructor(s) and Proctors
Explain the logistics for the session
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2. Basic Plotting Techniques
Dead Reckoning
Determining position from prior fix
Bearings
Visually establish a position
2 Bearings establish a fix
Related techniques
Ranges
Relative Bearings
Seaman’s Eye

3. SKILL – Dead Reckoning Maintain Position using SKILL Course &
Distance Traveled
SKILL
Plot and Label DR Courses

4. Dead Reckoning POSITION determined by: DISTANCE determined by:
Course Steered
Distance Traveled
DISTANCE determined by:
Direct-reading LOG
Speed x Time
60 Distance (nm) = Speed (knots) x Time (min)
or 60D = ST (called ‘60 D Street’)

5. Dead Reckoning Piloting 2004 - Chapter 3 4/24/2017
Figure 2-10 Dead Reckoning – In the absence of electronics, your actual location on the water must be estimated based on your last known position, the course steered and the distance traveled. This is known as Dead Reckoning and has been used for centuries to navigate. Distance traveled often is determined by using your speed on the water and time. With GPS, you will know your current location to a high degree of accuracy and thereby not use dead reckoning unless, for some reason, your electronics become unreliable. Then knowing basic dead reckoning can get you home.
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6. Dead Reckoning Formula
Distance = S x T 60
(distance traveled)
Speed = 60 x D
(average actual speed) T
Time = 60 x D
(elapsed time) S

7. DR Accuracy Helmsman Issues: Other factors: Accuracy of Course Steered
Cannot wander
Accuracy of Speed Reading
Difficult to obtain precise value
Measurement of Time
Other factors:
Currents & Winds
Obstacles and other boats
Fatigue

8. DR Plotting & Labeling DR Plot DR Position Direction of Course Steered
Nominally every hour
Calculate and Plot Distance traveled
Plot at every
Course or Speed Change
Label
Dot for location, surrounded by half-circle
Time labeled on diagonal

9. Labeling DR Courses 1030 C 070 M 1000 S 6.0
1. Draw & Measure COURSE LINE
using course direction
2. Label COURSE
near starting point
“C” (direction – 3 digits)
1030
C 070 M
4. Plot & Label DR Position
dot – half circle
Time (4 digits on diagonal)
1000
S 6.0
3. Label SPEED
near starting point
“S” (kn – 2 significant digits)
D = (S x T) / 60
D = (6.0 x 30) / 60
D = 3.0 nm
Fix

10. Exercise 3-1 – Plot & Label DR
Use Bowditch Bay Chart
Follow Instructions in Student Guide

11. Exercise 3-1 D = (ST)/60 D = (ST)/60 T = 075 D = (8.5x35)/60
How to maintain a DR plot. Using “Seaman’s Eye” to confirm DR positions.
At 0945, depart G “1” Fl G 2s Oyster River on a true course of 075º. Speed is 6.5kn.
At 1010, you change to a magnetic course of 355º.
At 1030, you increase speed to 8.5kn.
At 1105, you take up a true course of 090º.
What is a visual check on the DR position?
What is your sounding at the 1105DR position?
D = (ST)/60
D = (8.5x35)/60
D = 5.0nm
T = 090
V = 015W
M = 105
D = (ST)/60
D = (6.5x20)/60
D = 2.2nm
D = (ST)/60
D = (6.5x25)/60
D = 2.7nm
M = 355
V = 015W
T = 340
T = 075
V = 015W
M = 090
1105
C 105M S 8.5
C 355M S 8.5
1030
C 355M S 6.5
C 090M S 6.5
1010
0945

12. SKILL – Bearings Determine Position using SKILL
Visual Bearings to Charted Objects
SKILL
Plot and Label Bearings

13. Bearings Lines of Position (LOP)
Based on direction of visible charted Landmarks
Direction from boat to landmark
Plotted toward landmark
Your location is somewhere on that line
You cannot tell precisely where
You can estimate your position at the intersection
DR Plot and LOP
Taken on the Water
Plotted & Labeled in real time
Labeled
Time of LOP on top of line
Bearing (Magnetic) below line

14. Sight Bearing from Boat to Landmark

15. Plot & Label Bearing Label Time above the line, and Bearing below
1030
070 M

16. Methods – Taking Bearings
Hand-Bearing Compass
Every boat should have one
Handy
Reasonably accurate
Easy to use
Good as backup compass
Sight across ship’s compass
Limited
Inaccurate

17. Using Landmarks Piloting 2004 - Chapter 3 4/24/2017
Figure 3-3 Comparing GPS & Visual Bearings – Your GPS is quite reliable, but not infallible. It is important that you not rely on the GPS alone. It is quite easy to check it by comparing the bearing to a landmark as viewed on a hand-bearing compass with that shown on the GPS. If they match, the GPS is working. You will learn the details in Chapter 10.
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18. Exercise 3-2 - Plot & Label Bearings
Use Bowditch Bay
Follow instructions in Student Guide

19. Exercise 3-2 D = (ST)/60 D = (6.2x35)/60 D = 3.6nm MB = 355 V = 015W
Method for taking and plotting compass bearings. Plot and label the magnetic course, bearings & DR positions.
At 1005, depart R “8” I Q R Main Channel on a true course of 080º. Speed is 6.2kn.
At 1035, using a hand bearing compass, you take a bearing of 185º on R “6” Fl R4s Main Channel. Using “Seaman’s Eye”, how can you verify this bearing?
At 1110, you take a compass bearing of 355º on the Duttons Island light. What does this tell you about your speed? M M
1110
1035
C 095M S 6.2
1005
D = (ST)/60
D = (6.2x35)/60
D = 3.6nm
MB = 355
V = W
TB = 340
D = (ST)/60
D = (6.2x30)/60
D = 3.1nm
MB = 185
V = W
TB = 170
T = 080
V = 015W
M = 095

20. SKILL – 2-Bearing FIXes Develop a FIX using SKILL Two Bearings
Plot and Label Fixes

21. Fixes – 2 Bearings FIX Accuracy Intersection of 2 or more Bearings
Determined by accuracy of each bearing
Depends on angle between bearing
Too close, poor accuracy (< 30°) (> 150°)
90° = ideal (2 bearings)

22. 2-Bearing FIX

23. 2-Bearing FIX
1030
340 M
1030
070 M

24. Exercise 3-3 - 2 Bearing FIX
Use Bowditch Bay chart
Follow Instructions in Student Guide

25. Exercise 3-3 M = 077 V = 015W T = 062 D = (ST)/60 D = 6.0x36/60
Using two bearings to plot a fix.
At 0900, depart RW “OR” Mo (A) Oyster River on a true course of 350º. Speed is 6.0kn.
At 0936, you take a compass bearing of 285º on Chapman Point light and a compass bearing of 355º on the light house north of Shark River. At the 0936 fix, take up a magnetic course of 077º. Increase speed to 11kn.
What are the L and Lo of the fix?
Observe the 0936 DR and fix positions. What happended?
Using “Seaman’s Eye”, what can you say about your 0936 fix? M
C 077M S 11 M
41º 41.4’N
0936
0936
M =
V = W
T =
D = (ST)/60
D = 6.0x36/60
D = 3.6nm
CB = 355
V = W
TB = 340
T = 350
V = 015W
M = 005
CB = 285
V = W
TB = 270
C 005M S 6.0
0900
72º 01.3’W

26. SKILL – 3-Bearing FIXes Develop a FIX using SKILL
Three or more Bearings
SKILL
Plot and Label 3-Bearing Fixes

27. 3-Bearing FIX 3 Bearings May not line-up Potential for 3 intersections
Forms a triangle
Position nominally at center of triangle

28. BREAK FOR THIS CHAPTER

29. Relative Bearings Bearings using the Boat as reference
Used occasionally
Need obvious reference points on boat
Bow Bearings
Beam Bearings
Falls into category of “Seaman’s Eye”
Not precise, but good check

30. Relative Bearing Piloting 2004 - Chapter 3 4/24/2017
Figure 2-13 Relative Bearings – Sometimes it is more convenient to reference bearings from the boat. These are referenced to the bow of the boat and are called relative bearings. These bearings are measured clockwise from the bow. For example an object that is viewed to be abeam of the boat on the right (starboard) side will have a relative bearing of 90º. If the relative bearing is on the port side, its value is 270º.
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31. SKILL – Relative Bearings
Take Bearings relative to the Boat
Bow Bearing
Beam Bearing
SKILL
Plot and Label Relative Bearings

32. Bow Bearing
1030
070 M
070 M

33. Beam Bearing
070 M
90R
1030
160 M

34. Beam Bearing
1030
340 M
070 M
270 R

35. Exercise 3-4 - Relative Bearings
Use Bowditch Bay chart
Follow instructions in Student Guide

36. Exercise 3-4 T = 349 V = 015W M = 004 D = (ST) / 60 D=(6.0x47)/60
Using “Seaman’s Eye” to take bow and beam relative bearings.
At 1000, depart RW “OR’ Mo (A) on a true course of 349º. Speed is 6.0kn.
At 1019, you take a starboard beam bearing by “Seaman’s Eye” on R “10” Q R Main Channel.
At 1100, you briefly turn the bow toward Fl R 6s 40ft 10M HORN north of Shark River and take a bow bearing of 344ºM, and notice that the light on Chapman’s Point is exactly off your port beam. Plot the 1100 fix and steer a new course of 105ºM.
At 1147, you take a port beam bearing on the tower with a red light to the north. M M
1100
1147
C 105M S 6.0
1100 M
1019 M
C 004M S 6.0
T = 349
V = 015W
M = 004
D = (ST) / 60
D=(6.0x47)/60
D = 4.7nm
D= (ST)/60
D=(6.0x41)/60
D= 4.1nm
RB = 270
MH = 105
MB = 375
V = 015W
TB = 360
M = 105
V = W
T = 090
D = (ST)/60
D = 6.0x19/60
D = 1.9nm
RB = 270
MH = 344
MB = 254
V = W
TB =
RB = 000
MH = 344
MB = 344
V = W
TB =
RB = 090
MH = 004
MB = 094
V = 015W
TB = 079
1000

37. SKILL – Ranges Pre-plotted Bearings using
Two visible charted landmarks or
Navigation aids
Provides a visual cue on the water to
Stay on Course
Find a specific location
SKILL
Use Ranges, Plot and Label your own Ranges

38. Ranges Ranges are Pre-Plotted Bearings Uses Very Precise
Use two visible charted landmarks
Bearing line intersects both landmarks
Uses
Navigation in narrow channels
Alignment with Harbors
Formal navigation aids
Can build own to help navigate
Very Precise

39. Using a Range Piloting 2004 - Chapter 3 4/24/2017
Figure 2-12 Using a Range – Another positioning technique is called a range. This is nothing more than two visible, charted objects, that when aligned provide a particular heading. Navigation aids often are aligned in this way to help you stay within a narrow channel. The rear range aid is taller than the one in front. When you are in the channel, the two objects will align perfectly. If you wander off-course, the rear navigation aid will appear to be to the left of the other if you are to the left (port) of the channel. It is possible to construct your own ranges with any two visible objects that you can identify on the chart.
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40. Formal Range
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41. Informal Range
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42. Range Pictures

43. Exercise 3-5 - Ranges Use Bowditch Bay chart
Follow instructions in Student Guide

44. Exercise 3-5 – Ranges T = 185 V = 015W M = 200 T = 156 V = 015W
Select and measure ranges from any two charted landmarks.
Create a range to the entrance of Perkins Cove, approaching it from the North on a magnetic course of approximately 200º. Assume that the tower on the west side of Perkins Cove is illuminated and its height to be 40ft.
Plot the range and create a turn into Perkins Cove
C 171M
T = 185
V = 015W
M = 200
Range 200M
T = 156
V = 015W
M = 171

45. Seaman’s Eye Informal Ranges Bow & Beam Bearings
Other Reference Points on the Boat
Mark on rail

46. Using GPS to Navigate Using GPS
You get Precise Position – continuously
But, how do you navigate and stay safe?
Must periodically plot position on a chart
Essential to have reference to what is nearby
Or, along your path
Can be a tedious task

47. Better Approach: Pre-Planning
Create pre-qualified legs on the water
Qualify them to be free of obstacles
Then, On-the-water – follow the paths
Only need to refer to charts on occasion
Key – just stay on course

48. Pre-Planning
Make your plan
Follow your Plan

49. Characteristics of a Safe Path
Clear of Obstacles
Sufficient Depth for boat

50. Selecting a Safe Path Step-by-Step Draw ‘legs’ (paths)
Check for obstacles
Shallow Water
Rocks
Wrecks
Other Obstacles (poles, structures, etc.)
Safe Path Width
Nominally about 1/10th nm on each side
Equal to smallest increment on latitude scale
About 600 feet
Allows for helmsmanship, other boats, some drift

51. Minimum Path Width Piloting 2004 - Chapter 3 4/24/2017
Figure 5-7 Minimum Path Width - In pre-qualifying a path for navigation, you need to consider what lies along the centerline because you may stray from that line while on the water. Actually, you need to consider a number of factors such as inattention to the helm, avoiding other boats, action of the sea, and your GPS accuracy when determining safe clearance for a planned leg.
Generally, it is recommended that you allow at least about 10 times the accuracy of the GPS on either side to account for all of these factors. Since the GPS limit of accuracy is about 50 feet to a high degree of confidence, you should leave about 500 feet to either side of the intended path. Just to be on the safe side and for easy measurements, consider that the 0.1 minute tic-marks on the latitude scale represent about 600 feet. So, use that as a reference and check the clearance out to about one tic-mark’s width to either side of your intended path.
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52. Redrawn from “How to Read a Nautical Chart”
Piloting Chapter 3
4/24/2017
Hazard Symbols
Figure 5-3 Examples of Chart Symbols for Land and Rocks – The terrain is of primary interest to the boater. Much of it is below the waterline, some is exposed, and some is exposed under different tide conditions. Cartographers use a variety of symbols to depict these conditions. You should become familiar with these shown in the figure. Greater detail can be obtained from “How to Read a Nautical Chart” by Nigel Calder.
Land that is above high water is colored as tan or light brown. Land that is uncovered at low tide is colored in green on U.S. charts. Shallow water is usually colored as light blue. Deep water is white. The dividing line between shallow and deep is dependent upon the chart that you are using. Check the legend. Usually, it is in fathoms (6 feet) and typically will be an increment of 6ft, 12ft, 18ft, 30ft, etc.
On land, the heights are indicated by a number as shown for the small islands to the left of the figure. If there is insufficient space to place the number on the land, it may be shown in parenthesis as shown. These heights are based on the high-water datum (look at the chart to see what that is – usually Mean High Water – see Chapter 14)
Those that are exposed a low tide are called ‘uncovering.’ Generally, the reference for objects underwater is the low water datum (usually Mean Lower Low Water); however, an object that is higher than that must be marked differently. In this case, the depth is shown as a number in parenthesis with an underline below. This indicates that the depth is that value ABOVE the low water datum.
Some rocks may be ‘awash’ at low tide meaning that they are just exposed a bit. The symbols for rocks awash are shown. Dangerous underwater rocks that may lurk just below the surface have slightly different symbols – less the four dots around the ‘+’ sign. Finally, the charted depth to the bottom is shown by numbers generally representing feet below the low-water datum.
Redrawn from “How to Read a Nautical Chart”
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53. Symbols for Obstructions
Piloting Chapter 3
4/24/2017
Symbols for Obstructions
Figure 5-6 Symbols for Obstructions - Obstructions can take a variety of forms. Usually they are pilings or some other underwater structure. They are not always manmade and can consist of submerged stumps. Often, they will be noted without noting the depth. Unless you know better regarding the depth, stay clear. Otherwise, they will show the least depth known as shown in the figure.
Submerged piles, snags, or stumps are indicated by a small black circle showing the position within the limits of accuracy of the chart. In other words, allow for some clearance. Your GPS is likely to be more accurate than the chart.
From: “How to Read a Nautical Chart”
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54. What to look for… Use Navigation Aids Use visible landmarks Depth
Try to begin / end legs at navigation aids
Gives visible reference
Use visible landmarks
Provides a double-check reference
Take bearings as you go along
Depth
Sufficient clearance under the keel

55. Depth under the Boat Piloting 2004 - Chapter 3 4/24/2017
Figure 5-4 Safe Depth – Clearance Under the Boat – Determining the clearance under your boat is one of your primary planning tasks for selecting a safe path. The charted depth reflects the depth to the bottom at the low-water datum. You need to subtract the draft of your boat to determine the amount of clearance at that datum. Generally, cartographers will use MLLW (Mean Lower Low Water) for the datum, so most of the time the depth will be greater; however, at precisely lower low tide, half of the time it will be shallower than noted. In other words, leave a little margin, or make sure your passage is other than at low tide.
In areas with some significant tidal range, you might need to transit an area at other than low tide. You will need to be able to determine the actual height of the water at the time of transit. Chapter 14 explains how to do that.
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56. Working Around Obstacles
Build a Route Around Obstacles
Create multiple legs

57. Planning on a Chart Piloting 2004 - Chapter 3 4/24/2017
Figure Steps in Planning on a Chart - The first step in planning for a trip on the water is to note the coordinates of your starting and destination points. These you will want to store in your GPS. Next, draw the course line from Start to Destination to see if the path is clear. If it is not, you will need to add one or more legs around the obstructions. Then, you will need to measure the coordinates of any intermediate waypoint(s) and enter them into your GPS as well.
In the example shown in the figure, there are two dangerously shallow areas along the direct path, so an extra waypoint was added and its coordinates measured. The two resulting legs clear any of the shallow areas.
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58. Waypoint Terminology Piloting 2004 - Chapter 3 4/24/2017
Figure 2-8 Waypoint Terminology – Use of GPS and electronic navigation has popularized the use of Waypoint Navigation among boaters. A Waypoint is any location that you select to use. It’s location is defined by its coordinates (e.g., latitude and longitude) and a name. Between waypoints, the straight-line paths that you travel are called legs. Usually, a cruise from one place to another involves more than one leg. The current leg that you are navigating is called the Active Leg. The waypoint where you started the current leg is called the Active “From” Waypoint. The waypoint that you are heading toward is called the Active “To” Waypoint.
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59. Plotting Summary Piloting 2004 - Chapter 3 4/24/2017
Figure Summary of Plotting Techniques –There are two sets of plotting techniques depending upon whether they are part of your pre-planning, or are done on-the-water.
If you use the technique of making your plan and then following your plan, you will use those techniques shown on the left. Legs are plotted with course directions (and reciprocals – you did want to come back, right?). Waypoints are noted. You may note the coordinates on the chart, but it’s best to put them on a tablet in any event, and then enter them into the GPS from the tablet. Also, any ranges that you may plan on using should be plotted and labeled with the direction.
On-the-water (right part of figure), in the absence of the plan or in the event of a GPS failure, you will be performing dead reckoning wherein you will note the time of each fix and compute the distance traveled along your steered course to get your estimated position. Position fixes can be obtained by taking sighted bearings on charted landmarks. The bearings can be plotted on the chart to determine your position fix.
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60. Plotting Magnetic Courses
Piloting Chapter 3
4/24/2017
Plotting Magnetic Courses
Figure Plotting Magnetic Courses – Generally, you will want to plan, plot, and steer to magnetic courses. This makes a great deal of sense since you will be using your ship’s magnetic compass in steering the boat under most circumstances. Therefore, the language of the chart is true, and the language of the boat is magnetic. We need to convert.
The compass rose provides the direction for magnetic north as well as true north. The grid lines on the chart are aligned with true north, so the compass rose will become quite important to you. When you pre-plan, you should convert the measurements that you make using the grid lines to magnetic courses and label them on each leg. It is not necessary to label both true and magnetic, but if you use magnetic, place an ‘M’ after the course to distinguish it.
On-the-water using dead reckoning, you need to plot your steered course and label it as magnetic. If you take bearings, your reading from your hand-bearing compass will be magnetic. You need to plot them using the compass rose or calculate the difference between magnetic and true and add or subtract that from the reading before plotting using the grid lines as reference.
© 2004, “The Weekend Navigator”
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61. Digital Charting - CD

62. Digital Charting CD Chart Navigator Software Charts
Plot marks, waypoints, routes
Annotate charts
Upload, download to GPS
Edit
Charts
Bowditch Bay, 1210tr
Chart set – Block Is to Martha’s Vineyard
Nautical, Topo, Photo, Aerial – selected
Charts –
Small scale – Entire U.S. coasts, Great Lakes, Hawaii, Alaska, North Pacific, Caribbean areas, World

63. Autoplay Menu

64. Simple Tools

65. A to B Measurements

66. Marking on Chart

67. Quick Route

68. Questions ? … Comments Piloting 2004 - Chapter 3 4/24/2017
Surely, you have questions.
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