Piloting Course (Inland Navigation)

Chapter 3

Plotting and Planning Techniques

SEO – Dave Westdwest@voyager.net - 651-429-3840

Instructor – Art Mollicaartmollica@usfamily.net - 651-777-0277

United States Power Squadrons ®

Slide 2

Any questions on homework from Chapter 2?

1. The most common chart used on the water is a: (d) mercator projection. WN-Ch 4, pg 24

2. On a mercator chart all line of: (a) latitude and longitude are straight lines and intersect at 90º. WN-Ch 4, pg 24

3. A chart datum identifies, by letter and numbers, the: (c) coordinate systems. WN-Ch 2, pg 29 and SG-Ch 2, ¶ 8

4. Height of objects are indicated using as a reference: (a) mean high water (sometimes mean higher high water). WN-Ch 5, pg 58

5. A nautical chart shows detail of: (b) detail features both above and below the water. SG-Ch 2, ¶ 4

6. Large scale charts show a: (c) small area in great detail. WN-Ch 4, pgs 27-28

7. The labels for charted beacons and buoys are: (d) beacons vertical, buoys slanted. SG-Ch 2 ¶72-73

8. A lubber line is: (a) a fixed directional line on the compass. WN-Ch 4, pg 47

9. Variation is the angular distance between: (b) magnetic north and true north. SG-Ch 2, ¶ 104-106

Slide 3

10-14. Fill in the missing values in the following table.

SG-Ch 2, pgs 36-37

15. A fathom is: (b) 6 feet. SG-Ch 2, ¶ 18

16. The starboard side of a channel when returning from sea is marked with: (d) red color – conical (num) – even numbers. SG-Ch 2, pg 17

17. When entering from sea, a buoy marking the junction of two channels where the preferred course is to the left would be a _____ and would have a letter designation. (c) red over green (horizontal) nun SG-Ch 2, ¶ 28

18. Measuring distance on a chart use the horizontal scale (longitude) at the top/bottom of the chart. (b) False WN-Ch 4, pg 39

19. For a 3-D GPS fix you need: (d) four satellites. WN-Ch 4, pg 48

20. GPS provides you with: (c) current position. WN-Ch 4, pg 49

21. Depth sounders use a transducer to: (c) send acoustical sound downward through the water.

Any questions on homework from Chapter 2?

10. 11. 12. 13. 14.True 347º 122º 062º 237º 004ºVariation 11º E 13º W 5º E 14º W 10º EMagnetic 336º 135º 057º 251º 354º

Slide 4

Basic Plotting Techniques

Dead Reckoning• Estimated position using course steered and distance

traveled Distance determined by direct reading LOG or… 60D=ST formulas

• Determine position from prior FIX

Bearings• Visually establish a position

2+ Bearings establish a fix• Related techniques

Ranges Relative Bearings Seaman’s Eye

TRIP (NM)

Slide 5

Accuracy of DR?

Helmsman Issues:• 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

Slide 6

DR Plotting & Labeling

DR Plot• Shows direction and speed of courses

steered• Shows position from DR calculations

DR Position• Plotted

At every Course or Speed change Time of bearing Also nominally every hour

• Labeling Dot for location, surrounded by half-

circle Time labeled on diagonal

C 087 M

S 6.01000

Initial Fix

1030

Slide 7

Methods of 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 Sight lines may be limited Often less accurate Bow bearing

Slide 8

Bearing Plotting & Labeling

A Bearing gives a Line of Position (LOP)• You must be somewhere on that LOP• Cannot tell precisely where

Based on direction of visible charted Landmarks• Direction from boat to landmark• Plotted towards landmark

Taken on the Water• Plotted & labeled in real time• Labeled

Time of LOP on top of line Bearing (Magnetic) below line

C 087 M

S 6.01000

Initial Fix

1030

035M

1030

No longer teach assumed

position

Som

ewher

e on

this

lin

e

Slide 9

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 1030 DR position?

What is your sounding at the 1105 DR position?

0945 C 090M

S 6.5

C 355M

S 6.5

1010

1030

C 355M

S 8.5

1105 C 105M S 8.5

Exercise 3-1

T = 075V = +15WM = 090

D = (ST)/60D = (6.5x25)/60D = 2.7nm

M = 355V = -15WT = 340

D = (ST)/60D = (6.5x20)/60D = 2.2nm

D = (ST)/60D = (8.5x35)/60D = 5.0nm

T = 090V = +15WM = 105

Slide 10

Sight Bearing from Boat to Landmark

1035

351M

You are somewhere

on this line but don’t

know exactly where.

Slide 11

How to Plot a Bearing

C 087 M

S 6.01000

1030

035M

1030

MB = 035V = -15WTB = 020

TH

E O

UT

ER

SC

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RE

AD

FR

OM

A

ME

RID

IAN

OF

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NG

ITU

DE

. TH

E

INN

ER

SC

AL

E F

RO

M A

PA

RA

LL

EL

OF

LA

TIT

UD

E.

090

270

180

000

080

070

060050

040030 020 010 000

260

250

240230

220 210 209 190 180

100

110

120

130

140

150

160

170

180

280

290

300

310

320

330

340

350

360

170

160

150140

130

350

340

330320

310

190

200

210

220

230

010

020

030

040

050

Slide 12

Exercise 3-2Taking and plotting compass bearings. Plot and label the magnetic course, bearings and 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 Dutton’s Island light.

What does this tell you about your speed?

1005 C 095M

S 6.2

10351035

185M

1110

355M

1110

T = 080V = +15WM = 095

D = (ST)/60D = (6.2x30)/60D = 3.1nm

MB = 185V = -15WTB = 170

D = (ST)/60D = (6.2x35)/60D = 3.6nm

MB = 355V = -15WTB = 340

Slide 13

FIX’s from two Bearings

Two crossed Bearings give a FIX

Accuracy• Determined by accuracy of each bearing• Depends on angle between bearing

Too close, poor accuracy (< 30°) (> 150°)

90° = ideal (2 bearings)

90º

160º

+/- 2º Error

Somewhere inside red area

Slide 14

1035

351M

2 – Bearing FIX

1035 110M

Your FIX is at the intersection of the two LOP’s.

1035

Slide 15

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 356º on the light house north of Shark River. At the 0936 fix, take up a magnetic course of 077º. Increase speed to 11.0kn.

What are the L and Lo of the 0936 fix?

Observe the 0936 DR and fix positions. What happened?

Using “Seaman’s Eye”, what can you say about your 0936 fix?

Exercise 3-3

0900

C 005M

S 6.0

T = 350V = +15WM = 005

0936 285M

0936

356M

D = (ST)/60D = 6.0x36/60D = 3.6nm

CB = 285V = -15WTB = 270

CB = 356V = -15WTB = 341

09360936

M = 077V = -15WT = 062

C 077M

S 11.0

41º 41.4’N

72º 01.3’W

0936

Slide 16

1035

351M

1035 110M

1035

3 – Bearing FIX’s

May not cross at a single point. Position nominally at center of triangle.

1035

072M

10 9 8 7 6 5 4 3 2 1

10 MINUTE BREAK

PLEASE TAKE YOUR SEATS

Slide 18

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

Change in Relative Bearing useful for determining possibility of collision

Slide 19

Bow Bearing

240M

Slide 20

90º

Beam Bearing

C 153M

Starboard Beam

Bearing

MH = 153º RB = 090º MB = 243º

270º Port Beam

Bearing

MH = 153º RB = 270º MB = 063º

243M 063M

Slide 21

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.

Exercise 3-4

1000

C 004M

S 6.0

T = 349V = +15WM = 004

1019

094M

1100

344M

D = (ST)/60D = 6.0x19/60D = 1.9nm

RB = 090MH = 004MB = 094V = -15WTB = 079

1019

1100

D= (ST)/60D=(6.0x41)/60D= 4.1nm

1100

254M

RB = 000MH = 344MB = 344V = -15WTB = 329

1100

RB = 270MH = 344MB = 254V = -15WTB = 239

M = 105V = -15WT = 090

C 105M S 6.0

D = (ST) / 60D=(6.0x47)/60D = 4.7nm

1147

RB = 270MH = 105MB = 375V = -15WTB = 360

1147 015M

Slide 22

Ranges

A Range is a bearing using• Two visible charted landmarks or Navigation aids

Provides a visual cue on the water to staying on course

Uses• Navigation in narrow channels• Alignment with Harbors• Can build own to help navigate

Very Precise

© 2003, R J Sweet, “GPS for Mariners.” Reprinted with permission© 2004, “The Weekend Navigator”

Slide 23

Formal Range

Slide 24

Outside Range

© 2003, R J Sweet, “GPS for Mariners.” Reprinted with permission© 2004, “The Weekend Navigator”

Slide 25

Informal Range

Slide 26

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

Exercise 3-5 – Ranges

T = 184V = 015WM = 199

Range 199M

T = 156V = 015WM = 171

C 171M

Slide 27

Using GPS to Navigate

GPS gives you your position – precisely and 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• Or, beneath you• Can be a tedious task• Best approach -

Create pre-qualified legs on the waterand Follow your plan

Slide 28

Characteristics of a Safe Path

Clear of Obstacles and Sufficient Depth for boat

1) Draw ‘legs’ (paths)

2) Check for obstacles• Shallow Water• Rocks• Wrecks• Other Obstacles

3) 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

© 2003, R J Sweet, “GPS for Mariners.” Reprinted with permission© 2004, “The Weekend Navigator”

Slide 29

Minimum Path WidthEDF

WFBGC

Slide 30

Working Around ObstaclesEDF

WFBGC

WFBSS

XTE 0.4

Slide 31

Digital Charting CD

Coastal Explorer Viewer Software• Plot marks, waypoints, routes• Annotate charts (Raster)• 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

Slide 32

Coastal Explorer Viewer

Supplementary aid to navigation,

not a primary tool!

Slide 33

Coastal Explorer ViewerTitle Bar

Tab/Status BarTool Bar

Chart Window

Overview

Properties

Last thing in main chart you clicked on.

Chart info ‘read only’

Mark, route bearing, range can be changed

Slide 34

Coastal Explorer Viewer Tools

Slide 35

Coastal Explorer Viewer Tools

Chart Portfolio

Install Charts

Configure GPS

Program Options

Help & Support

Slide 36

Coastal Explorer Viewer Tools

Slide 37

Questions ? … Comments

Slide 38

Homework

Read Chapter 4 – Student Guide

Review Chapters 4 & 5 – Weekend Navigator

Do Chapter 3 homework

Next class – 14 February