Transcript P Ch 04 On the Water - St. Paul Sail and Power Squadron

United States Power Squadrons
®
Piloting Course
(Inland Navigation)
Chapter 4
On the Water
SEO – Dave West
[email protected] - 651-429-3840
Instructor – Art Mollica
[email protected] - 651-777-0277
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:
3.
Distance
5.1nm
Time
38mins
Speed
8.1kn
SG-Ch 3, ¶ 20
9.
4.
5.
46nm
12.6nm
6hr 34min 1hr 7min
7.0kn
11.3kn
6.
10nm
27min
22.0kn
7.
8.
15nm
12.9nm
1hr 30min 1hr 45min
10.0kn
7.4kn
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
Slide 2
Any questions on homework from Chapter 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:
Magnetic Bearing
Relative Bearing
Magnetic Heading
13.
080º
010º
070º
14.
300º
125º
175º
15.
250º
022º
228º
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
Slide 3
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 4
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 5
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 6
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 7
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 8
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
$50
$200
• Turns smoothly on your boat
• Sail & Powerboat compasses are different
 Largest you can afford
• Easier to read, smoother movement
• Top reading preferred
$1,900
Slide 9
Errors Affecting Compasses
Things on your boat can affect compass…
 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
Slide 10
Boat Effects on Compass
In another direction the metallic
mass may have a much greater
effect on the local magnetic field
In one direction the metallic
mass may have little effect
on the local magnetic field
© 2004, “The Weekend Navigator”
Slide 11
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 12
Deviation Table
 Table of Corrections
Deviation Table
Magnetic
Degrees
000°
045°
090°
135°
Magnetic to Compass
Deviation
Magnetic
Degrees
Degrees
180°
1°W
2°W
225°
2°W
270°
1°W
315°
Deviation
Degrees
0°
2°E
1°E
1°E
Compass
Degrees
000°
045°
090°
135°
Compass to Magnetic
Deviation
Compass
Degrees
Degrees
180°
1°W
2°W
225°
2°W
270°
1°W
315°
Deviation
Degrees
0°
2°E
1°E
1°E
Ref: WN Ch 28 – Measuring Compass Deviation using GPS
Slide 13
Correcting True to Compass
subtract West
add East
True
add West
subtract East
Variation
M
subtract West
add East
Magnetic M
Deviation
Compass
add West
subtract East
 When converting from True to Compass
© 2004, “The Weekend Navigator”
• “West is Best” – add West
• “East is Least” – subtract East
Slide 14
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 15
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°
Slide 16
10 MINUTE BREAK
10
9
8
7TAKE
6 YOUR
5
4 SEATS
3
2
PLEASE
1
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 18
3 Scales on Compass Rose
Outer scale aligned with True North
Middle scale aligned with Magnetic North
Slide 19
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.
© 2004, “The Weekend Navigator”
Slide 20
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.
© 2004, “The Weekend Navigator”
Slide 21
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.
T = 066
V = 015W
M = 081
Slide 22
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.
T = 267
066
V = 015W
M = 282
081
Slide 23
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.
M
T == 220
267
V = 015W
T
M== 205
282
Slide 24
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.
M = 029
220
V = 015W
T = 014
205
Slide 25
Questions ? … Comments
Slide 26
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 27
Appendix A – Piloting Cruise
Slide 28