Piloting Course (Inland Navigation)

Chapter 4

On the Water

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 3?

1. In plotting a pre-planed course, use the following to represent your intended path: (d) a solid line with the course labeled. WN-Ch 5, pg 61

2. To find a DR position and plot it on a chart you must: (d) calculate the distance from a prior position. SG-Ch 3, ¶ 7

3-8. Calculate and fill in the missing values in the table below:

SG-Ch 3, ¶ 20

9. In order to convert a magnetic bearing to a true bearing you must apply variation based on the boat’s position. (a) True. WN-Ch 5, pg 63-64

10. The direction of a bearing is: (c) measured from the boat to the navigational aid. SG-Ch 5, ¶

11. A starboard beam bearing is a relative bearing at: (c) 90º from the bow. SG-Ch 3, fig 3-5b&c

3. 4. 5. 6. 7. 8.Distance 5.1nm 46nm 12.6nm 10nm 15nm 12.9nmTime 38mins 6hr

34min1hr

7min27min 1hr

30min1hr

45minSpeed 8.1kn 7.0kn 11.3kn 22.0kn 10.0kn 7.4kn

Slide 3

12. A relative bearing is measured from: (c) the bow of the boat. SG-Ch 2, pgs 36-37

13-15. Calculate and fill in the missing values in the table below:

SG-Ch 3, ¶ 42

16. A navigation range consists of ____ navigational aids aligned to direct you along a path of water. (b) two. SG-Ch 3, ¶51

Any questions on homework from Chapter 3?

13. 14. 15.Magnetic Bearing

080º 300º 250º

Relative Bearing 010º 125º 022ºMagnetic Heading

070º 175º 228º

Slide 4

Responsibilities of the Skipper

You are responsible for the safety of

• Your crew• Your boat

You decide on navigation

• Use the techniques that ensure your safety

The Piloting Course provides the tools

• It’s up to you to decide how to apply them

Slide 5

The Basic Technique

GPS is your primary position sensor

Ship’s Compass for Steering

Seaman’s Eye to keep in touch with surroundings

Hand-Bearing Compass to take bearings

Plot GPS Position at regular intervals (~1hr)• Verify position via independent means

Slide 6

View from the Water

Study charts so you know what to look for

Learn to recognize ‘on-the-water’ views• Navigation Aids• Landmarks• Land Features

Practice on clear days so you know the landscape when it turns restricted

Slide 7

Use GPS as Primary Position Sensor

GPS must be properly set up

• Chart Datum -- WGS 84 (or other as required)

• Latitude & Longitude (grid) Degrees, Minutes, Tenths of Minutes for most coastal

charts Degrees, Minutes, Seconds for many inland charts

• Magnetic directions (preferred, auto set)

• Distance and Speed – match the chart Coastal

– Nautical Miles (nm) & Knots (kn) Great Lakes and inland lakes and rivers

– Statute Miles (mi) & Miles per Hour (mph)

Slide 8

Use the Compass for Steering

GPS is NOT a compass• It provides direction based on movement history• Will not work in static situation

Compass is easier to steer with• May need to use GPS to get oriented• Then, read and follow the compass heading

Slide 9

Attributes of a Quality Compass

Repeatability• Always returns to the same reading

When returned to the same heading or, when temporarily diverted using a

magnet or metallic object

Damping• Turns smoothly on your boat• Sail & Powerboat compasses are different

Largest you can afford• Easier to read, smoother movement• Top reading preferred

$50

$200

$1,900

Slide 10

Errors Affecting Compasses

Metallic Objects• Alter local magnetic fields• Can cause compass errors

Current-carrying Wires• Create their own magnetic fields• Interfere with Earth’s field near compass

Compass Error – called DEVIATION• Dependent upon heading of boat

Things on your boat can affect compass…

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

Slide 11

Boat Effects on Compass

In one direction the metallicmass may have little effect on the local magnetic field

In another direction the metallicmass may have a much greatereffect on the local magnetic field

Slide 12

Dealing with Deviation

Compass can be adjusted• To counteract local deviation• Via compensating magnets in compass

Compass Adjusting• Recommend a professional adjuster

Residual Deviation• Even after compensation – some deviation• May need to correct compass readings to

magnetic (or vise-versa)

Slide 13

Deviation Table

Table of Corrections

Deviation Table

Magnetic to Compass Compass to Magnetic

Magnetic Degrees

Deviation Degrees

Magnetic Degrees

Deviation Degrees

Compass Degrees

Deviation Degrees

Compass Degrees

Deviation Degrees

000° 1°W 180° 0° 000° 1°W 180° 0° 045° 2°W 225° 2°E 045° 2°W 225° 2°E 090° 2°W 270° 1°E 090° 2°W 270° 1°E

135° 1°W 315° 1°E 135° 1°W 315° 1°E

Ref: WN Ch 28 – Measuring Compass Deviation using GPS

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

Slide 14

TT

VV

MM

DD

CC

Correcting True to Compass

TTruerue

VVariationariation

DDeviationeviation

CCompassompass

add West subtract East

MM MM

add West subtract East

subtract West add East

subtract West add East

When converting from True to Compass• “West is Best” – add West• “East is Least” – subtract East

MMagneticagnetic

Slide 15

Practical Magnetic Compass Use

Typical Compass• 5° - graduated increments• Read to about 2-3°

Properly corrected compass• Residual Deviation typically < 2°• Ignore Deviation for moderate runs

Slide 16

Fluxgate Compass

Economical Electronic Compass

Uses electronics to sense the magnetic field

Self-compensating• automatically builds deviation table• automatically applies deviation to reading• continuously updates deviation table

Extremely Accurate• Typically < 1°

10 9 8 7 6 5 4 3 2 1

10 MINUTE BREAK

PLEASE TAKE YOUR SEATS

Slide 18

Plotting Magnetic

4 x 15 Plotter uses Grid Lines• Measures True not Magnetic• Requires TVM conversion

Alternative to using Grid Lines• Use Compass Rose• Middle scale is oriented to Magnetic• Measure using parallel rules• Or parallel lines on 4x15 plotter

Slide 19

3 Scales on Compass Rose

Outer scale aligned with True North

Middle scale aligned with Magnetic North

Tra

mon

tan

a

Ostro

Ponente

Levante

Gre

co

Libe

ccio

Siroco

Maestro

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

Slide 20

Parallel Ruler with the Compass Rose

1. Put pencil tip or divider point on center of compass rose.

2. Mark rose scale at course. (130º)

3. Align parallel ruler with center of compass rose and course (either magnetic or true.

4. Walk parallel ruler to position.

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

Slide 21

Rolling Plotter w/the Compass Rose

1. Put pencil tip or divider point on center of compass rose.

2. Mark rose scale at course. (092ºM)

3. Align rolling plotter with center of compass rose and course (either magnetic or true.

4. Roll plotter to position.

THE OUTER SCALE IS READ FROM A

MERIDIAN OF LONGITUDE. THE

INNER SCALE FROM A PARALLEL

OF LATITUDE.

090

270

180

000

080 070060

050

040

030020

01000

0

260 250240

230

220210

209190

180

100

110

120

130

140

150

160

170

180

280290

300

310

320

330

340

350

360

170 160 150140

130

350 340 330 320

310

190200

210

220

230

010020

030

040

050

Slide 22

Exercise 4-1

C 081M

T = 066V = 015WM = 081

Plotting with rectangular course plotter and parallel ruler using the Compass Rose.

Plot a course from G “7” Fl G 4s Main Channel to G “5” Fl G 4s GONG Main Channel. Measure and label the magnetic course using parallel rules and the nearest compass rose.

Slide 23

Exercise 4-1

C 081M

T = 066V = 015WM = 081

T = 267V = 015WM = 282

THE OUTER SCALE IS READ FROM A

MERIDIAN OF LONGITUDE. THE

INNER SCALE FROM A PARALLEL

OF LATITUDE.

090

270

180

000

080 070060

050

040

030020

01000

0

260 250240

230

220210

209190

180

100

110

120

130

140

150

160

170

180

280290

300

310

320

330

340

350

360

170 160 150140

130

350 340 330 320

310

190200

210

220

230

010020

030

040

050

C 282M

Plotting with rectangular course plotter and parallel ruler using the Compass Rose.

Plot a course from G “7” Fl G 4s Main Channel to G “5” Fl G 4s GONG Main Channel. Measure and label the magnetic course using parallel rules and the nearest compass rose.

Plot a course from R “6” Fl R 4s Main Channel to R “8” I Q R Main Channel using the rectangular course plotter and the nearest compass rose.

Slide 24

T = 267V = 015WM = 282

Exercise 4-1

C 081M

C 282M

M = 220V = 015WT = 205

THE

OU

TER

SC

ALE

IS R

EA

D F

RO

M A

ME

RID

IAN

OF

LON

GIT

UD

E. T

HE

INN

ER

SC

ALE

FR

OM

A P

AR

ALL

EL

OF

LATI

TUD

E.

090

270

180

000

080

070

060050

040 030 020 010000

260

250

240230

220 210 209 190180

100

110

120

130

140

150

160

170

180

280

290

300

310

320

330

340

350

360

170

160

150140

130

350

340

330 320 310

190

200

210

220

230

010

020

030

040

050

C 2

20M

Plotting with rectangular course plotter and parallel ruler using the Compass Rose.

Plot a course from G “7” Fl G 4s Main Channel to G “5” Fl G 4s GONG Main Channel. Measure and label the magnetic course using parallel rules and the nearest compass rose.

Plot a course from R “6” Fl R 4s Main Channel to R “8” I Q R Main Channel using the rectangular course plotter and the nearest compass rose.

Plot and label a course of 220º magnetic from R “4” Fl R 6s BELL Main Channel using the rectangular course plotter and the nearest compass rose.

Slide 25

M = 220V = 015WT = 205

Exercise 4-1

Plotting with rectangular course plotter and parallel ruler using the Compass Rose.

Plot a course from G “7” Fl G 4s Main Channel to G “5” Fl G 4s GONG Main Channel. Measure and label the magnetic course using parallel rules and the nearest compass rose.

Plot a course from R “6” Fl R 4s Main Channel to R “8” I Q R Main Channel using the rectangular course plotter and the nearest compass rose.

Plot and label a course of 220º magnetic from R “4” Fl R 6s BELL Main Channel using the rectangular course plotter and the nearest compass rose.

Plot and label a course of 029º magnetic from G C “1” Perkins Cove using parallel ruler and the nearest compass rose.

C 081M

C 282M

C 2

20M

M = 029V = 015WT = 014

C 0

29M

Slide 26

Questions ? … Comments

Slide 27

Cruise and Homework

Read Chapter 5 – Student Guide

Review Chapter 5 – Weekend Navigator

Do Chapter 4 homework

Do Part I of cruise (next slide)

Next class – 21 February

Slide 28

Appendix A – Piloting Cruise