Underway
Practice Cruise – Part 2
Homework
Q&A
Junior Navigation
Chapter 13
1
The homework for this Chapter
consists of executing a portion of
the voyage that you planned for
in Chapter 11.
This Practice Cruise will provide a
review of the entire course and
help you prepare for the course
exam.
2
To complete this cruise, you will need:
• your Navigator’s notebook and the completed homework
from Chapter 11;
• the pilot chart for July included with your student material;
• the Excerpts from the Nautical Almanac, contained in
Appendix B of your Student Manual, for all daily data and
Altitude corrections to complete the sight reductions;
• a copy of any edition of the Nautical Almanac for the
“Increments & Corrections” tables;
• blank copies of the Meridian Transit Form included at the
end of Chapter 9;
• blank copies of the Deck Log included at the end of this
chapter;
• Universal Plotting Sheets, Sight Reduction forms and CLS
plotting sheets, included with your student materials.
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Practice Offshore Cruise - Underway
The critical items in your Navigator’s notebook
related to taking celestial observations are:
■ Height of eye: 10.0 ft
■ Index Error (IE): Off the Arc, 0° 01.9’
(Check before each observation)
■ Watch error (WE): f 0-13 seconds
This leg of your cruise starts on 29 June 20XX.
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1. As part of your planning, you divided this voyage
into 3 segments (Chapter 11 homework, Question
#2) and planned to plot each voyage segment on a
separate Universal Plotting Sheet (UPS). You are
near the end of the first segment of the voyage and
are about to start the second voyage segment.
• Prepare UPS No. 2, using the Mid-Latitude of 37°N and
Mid-Longitude of 68° W.
• From your voyage plan, you note that the variation in this area is
15° W. Plot the 15° W isogonic line using points
L1 39° 00’N, Lo1 69° 20’W and L2 35° 00’N, Lo2 66° 45’W.
• You also note that this UPS includes an area where the time zone
changes. Plot the appropriate time zone boundary on UPS No. 2.
• You locate two waypoints on Plotting Sheet No.2 to mark the
intended course for this voyage segment. Plot and label
WP1 at
LWP1 38° 18.8’N, LoWP1 69° 14.3’W, and
WP2 at
LWP2 35° 37.5’N, LoWP2 67° 03.5’W.
5
Problem 1. Continued from previous slide
a. What is the magnetic course along the
162°M
rhumb line of this segment? ______
Click to view Ships Compass
Deviation Table
b. What should be the planned compass
160°
course along this rhumb line? ______
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2. You transfer data from your Navigator’s notebook and
review the pilot chart. You note that your intended
route for this segment crosses two major shipping
lanes, Cape Hatteras to Virgin Rocks and Cape Hatteras
to Gibraltar (Chapter 11 homework, #1h). You mark
the intersection of the shipping lanes and your route
with WP3 for the Virgin Rocks route and WP4 for the
Gibraltar route, and check these waypoints in your
GPS. You also make a note in your Navigator’s
notebook to closely monitor the radar when in the
region of the two waypoints, based on the captain’s
standing orders regarding radar contacts.
■ Plot WP3 & WP4, as well as the course these shipping lanes
cross your rhumb line course, on your Plotting Sheet #2. The
data recorded in your Navigator’s notebook is:
WP3: L37° 50’N, Lo 68° 20’W.
Course 058°
WP4: L36° 40’N, Lo 67° 20’W.
Course 071°
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3. 0400. As you begin your watch and start the DR
plot, you note the ship’s heading, psc, is 133° C
and speed has been 6.8 kn. The GPS indicates a
position of L 38°32.6’N, Lo 69°49.1’W. The
ship’s knotmeter log reading is 0579.0.
Conditions overnight have been Force 3 winds.
119°
a. What is the true DR Course? _______
b. At 0400, what is the range and bearing
30.6 nm, 117° T
to waypoint WP1? ________________
• 0428. Received NOAA weather fax; logged receipt and
placed copy in Navigator’s notebook.
9
4. 0800. The GPS indicates a position of L 38°25.0’N,
Lo 69°15.8’W. The ship’s heading is 133°C and the
knotmeter log reading is 0606.1. Wind is Force 3 with
scattered white caps. You report the position to the captain.
• Plot the 0800 GPS Fix and DR position, and the CMG from the
0400 GPS fix on a CLS plotting sheet, using L 38°30’N and
Lo 69°30’W for the mid-Lat and mid-Longitude.
a. What has been the true CMG from the 0400 GPS Fix?
106°
_____
6.8 kn
b. What has been the speed through the water (S)? ______
(use the knotmeter log readings to determine this)
L38° 19.5’N, Lo 69° 18.8’W
c. What are the 0800 DR coordinates? ___________________
Set 023°, Dft. 1.5 kn
d. What is the set and drift at 0800? ________________
Click to view 0800 Set & Drift
CLS Plotting Sheet Solution
10
5. The current has put you off course to the northeast, so you
decide to restart your DR course from the 0800 GPS fix to
WP1, adjusting for current. Weather and wind conditions have
remained constant so you estimate your speed (S) will
continue to be 6.8 kn for this leg.
• Draw a current vector diagram to determine the true course to
allow for the current determined in Question #4.
Click to view
0800 Current Vector Diagram
a. What is the true course from the 0800 GPS fix to
169° T
WP1, not adjusting for current? _______
b. What is the true course from the 0800 GPS fix to
176° T
WP1, adjusting for current? ________
5.5 kn
c. What is your expected SOA? _______
d. What is the compass course to WP1, adjusting
188°
for current? ______
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6. 0910: You reach WP1 according to your GPS and change
course to WP2, restarting the DR plot. You check the
plotted course line between WP1 and WP2 and confirm it
to be 147°T. Knotmeter log reading is 0614.0.
• You wish to check your sight-taking accuracy by getting
a RFix using an LOP of the Sun now, and later in the day,
a Meridian Transit of the Sun.
• At 09-15-15 you obtain a good observation on
the Sun’s upper limb and record an hs of 55° 59.5’.
The knotmeter reading is 0614.6.
• Reduce this sight. Use your 0915 DR position as the
reference position. Plot the resultant LOP on a CLS
plotting sheet, using L 38°N and Lo 69°W for the midLat and mid-Longitude, and determine the 0915 EP.
14
Problem 6. (continued from previous slide)
a. What is your 0915
L38°18.3’N, Lo69°13.9’W
DR position?
____________________
b. What is Ho?
55° 41.8’
________
4.7 nm Toward
c. What is the intercept? _____________
105°
d. What is the azimuth? _____
Click to view solution on
Sight Reduction Form
e. What are the 0915 EP coordinates?
L 38°17.1’N, Lo 69°08.1’W
____________________
Click to view
CLS Plot of 0915 EP
15
11/18/2012
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7. 1000. In preparing to take a Meridian Transit sight, you
want to calculate the time that transit of the sun will
occur. Based on the time of yesterday’s Meridian Transit,
you estimate that Meridian Transit will occur today
around ZT 1140. The knotmeter log reads 0620.0.
Winds have increased, waves 1-2 ft.
• Plot your expected 1140 DR position on Plotting
Sheet #2, using the boat speed (S) experienced
during the period 0915 - 1000.
a. What is your 1140 DR position?
_____________________
L 38°03.7’N, Lo 69°01.8’W
b. Using your 1140 DR Lo, what is the calculated
time of MT? ____________
ZT 11-39-34
• 1052. Received NOAA weather fax; logged receipt
and placed copy in Navigator’s notebook.
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8. 1130. You prepare to take sights for the Meridian
Transit and start before your calculated time of MT.
You take a run of sights, selecting the observation
on the sun’s lower limb at WT 11-39-48 with hs of
74° 56.1’. You note that the 1140 GPS position is
L 38°03.5’N, Lo 69°02.1’W. The knotmeter log
reads 0632.2, which you use to calculate your
current DR position.
• Reduce the sight, using the Meridian Transit
Form contained at the end of Chapter 9.
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Problem 8. (continued from previous slide)
75° 10.6’
a. What is Ho? _________
b. What is the calculated latitude from your
L 38°01.5’N
meridian transit sight? __________
c. What is the difference between the calculated
latitude from your MT sight and the latitude
2.0 nm
given by the GPS? ________
Click to view solution on
Meridian Transit Form
20
9. Plot the MT observation on the CLS plotting sheet
you prepared for Question #6. Advance the 0915
Sun LOP for a RFix with the 1140 MT.
a. What are the coordinates of the 1140 RFix?
L 38°01.5’N, Lo 68° 56.4’W
_______________________
b. What is the distance between the 1140 GPS fix and
4.9 nm
the 1140 RFix? _______
Click to view CLS Plot of 1140 RFix
• With the distance between the 1140 GPS fix and
1140 RFix small, you’re confident that the GPS is
working properly. You decide to re-start your DR
course line from your next GPS fix.
22
10. 1200. The GPS indicates a position of L 38°01.0’N,
Lo 69° 00.0’W and the knotmeter log reading is 0634.9.
Winds are Force 4 with waves 2-3 ft. After you make your
entry in the ship’s Deck log and report the position to the
captain, you check on the NOAA radiofax chart issued at the
1052 weather broadcast. The low pressure system that you
had been following during previous forecasts, located off the
Carolina coast, is developing faster than expected.
• The forecast indicates that the system is on a course of 035°
at a speed of 13 mph and is predicted to cross L35° 00’N,
Lo75° 00’W in 24 hours.
•
After conferring with the captain, you decide to avoid the
worst of the system by changing to a course of 125° T, 90
degrees to the system’s track, and increasing boat speed (S).
•
Re-start your DR plot from the 1200 GPS position and locate
WP5 150 miles away.
24
Problem 10. (continued from previous slide)
a. What is the compass course to WP5?
139° C
________
b. What are the coordinates of WP5?
L 36°35.0’N, Lo 66° 25.5’W
___________________________
25
Problem 10. (continued from previous slide)
■ Further evaluation of the weather data indicates that the
system is approximately 200 miles in diameter with winds
that could approach Force 5. You note that the winds will
shift from the SW to S, and then to the SE as the system
passes. You decide to:
• Start logging your position, either DR or GPS, every
two hours until the weather system passes.
• Follow the route from the 1200 fix to WP5.
• Instruct the helmsman to follow the route as closely
as possible, but to also follow the wind to minimize
the strain on the boat and crew.
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11. 1400. The knotmeter log reads 0651.9.
Winds are at Force 4 and increasing.
• Plot the 1400 position on Plotting Sheet #2,
and make the appropriate Deck Log entry.
27
12. 1600. The knotmeter log reads 0668.9 and the GPS
position is L 37°54.5’N, Lo 68°17.7’W. Winds have
increased to Force 5, waves to 5 ft with some spray.
After plotting and logging the 1600 GPS position you
compare the past two log entries with your plotting
sheet. You make note that the SMG for the past 4 hours
has been 8.5 kn.
You note that the 1600 GPS position is NE of the course
line to WP5; this doesn’t concern you, since helmsman
was instructed to follow the winds to minimize the strain
on the boat and crew, and the winds from the storm
have been primarily from the SW. You also note that the
1600 position is very close to the shipping lane between
Cape Hatteras and Virgin Rock.
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Problem 12. (continued from previous slide)
• You immediately have the radar turned ON, and confirm
it is operating and being monitored by one of the crew.
• Plot the 1600 GPS position on Plotting Sheet #2, and
make the appropriate Deck Log entry.
a. What is the distance from your 1600 position
to where you will cross the Cape Hatteras
4.7 nm
to Virgin Rock shipping lane?
_________
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13. 1614. The radar picks up a large contact at a range
of 25.5 nm, on a bearing of 073°T; the GPS
position at this time is L37°54.2’N, Lo68°15.4’W
and the knotmeter log reads 0670.9.
Twenty minutes later, the GPS indicates your
position is L37°53.6’N, Lo68°11.7’W with a
knotmeter log reading of 0673.7; a second radar
reading at this time indicates the contact at a
range of 14.9 nm, bearing 076°T.
• Plot this situation on a CLS plotting sheet,
using L 38°N and Lo 68°10’ W for the
mid-Latitude and mid-Longitude.
30
Problem 13. (continued from previous slide)
237° (+/- 5°)
a. What is the ship’s course? _____________
24.9 kn (+/- 1 kn)
b. What is the ship’s speed? ________________
c. What time will the ship cross your track?
1656 (+/- 1 min)
________________
d. What time will your vessel cross the ship’s path?
1719 (+/- 1 min)
________________________
Click to view Ship Crossing
CLS Plotting Sheet
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Problem 13. (continued from previous slide)
• You note the ship’s closest point of approach (CPA)
may be within the 4.0 nm limit of the captain’s
standing orders.
e. Should circumstances require it, what true course
057° (+/- 5° )
should you be prepared to make? _______________
(180° from the ship’s course)
f. What would be the compass
course for this action?
073° (+/- 5°)
_____________
33
Problem 13. (continued from previous slide)
• Although there appears to be no need for avoidance
action, you report your position and intention to the
captain. He agrees that no course change is necessary.
• 1652. Received NOAA weather fax; logged receipt
and placed copy in Navigator’s notebook.
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14. 1730. The GPS indicates a position of L 37°52.1’N,
Lo 68°01.8’W. The knotmeter log reads 0681.7. Winds are
F5, with waves 6 ft. The ship is now well past your position.
• Checking your DR plot of the past several hours, you
decide to determine the set and drift indicated by the
1600 GPS fix. You used the 1600 knotmeter log reading
to calculate the speed and distance from the 1200 GPS
position, and then plotted the 1600 DR and the GPS
positions on a CLS plotting sheet, using L 38°N and
Lo 68°30’ W for the mid-Latitude and mid-Longitude.
a. What were the 1600 DR coordinates?
L 37° 41.5’N, Lo 68° 24.7’W
_________________________
023°
b. What was the set at 1600? _____
3.5 kn
c. What was the drift at 1600? ______
d. What was the true CMG between
101°
1200 and 1600?
_______
Click to view
1600 Set & Drift
CLS Plotting Sheet
35
Problem 14. (continued from previous slide)
• You decide to change course to WP2, re-starting the DR
plot from the 1730 GPS position and accounting for the
newly calculated set and drift. Draw a new current
diagram to determine your new course to steer and
expected speed of advance to WP2.
e.
What will be the compass course
189°
to steer to WP2?
_________
f. What will be the speed of advance
5.5 kn
as you proceed to WP2?
__________
Click to view
1730 Current Vector Diagram
37
Problem 14. (continued from previous slide)
• You instruct the helmsman to change to this new
course.
• Due to the winds and sea state, you continue the
1200 orders to the helmsman to follow the wind to
minimize stress on the boat and crew. You expect the
weather conditions will continue to set the boat to the
NE. You decide to cover the 1600 to 1730 events by
plotting only the two GPS positions for those times on
the UPS sheet, and inserting a note on the UPS
referencing the previous CLS plotting sheet.
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15. 1800. The knotmeter log reads 0686.0. Winds
have decreased a bit but are still at Force 5 and
waves are running to 4-5 ft. You review the 1642
weather fax and find that the storm is predicted
to pass your present position quickly and that
winds should start to moderate in the next hour.
16. 2000. You record the GPS position of
L 37° 38.9’N, Lo 67° 56.0’W in the Deck Log
and report this position to the captain. The
knotmeter log reads 0703.0. The winds continue
to moderate slightly and sea conditions improving.
• Plot your 2000 GPS position.
17. 2200. The knotmeter reading is 0720.0.
Winds are at F4, with waves at 3-4 ft.
• Plot your 2200 position.
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18. 2400. You review the Deck Log, making the 2400
entry. You log the GPS position of L 37°17.7’N,
Lo 67°46.8’W and the knotmeter reading of
0737.0. Winds have dropped to F3 and conditions
are continuing to improve. You plot this position on
Plotting Sheet #2 and label the change of date.
a. If you were to continue your watch beyond 2400,
what change would need to be made in the log?
Start a new Deck Log page, with new date.
_________________________________________
• Having only caught short naps throughout the
storm, you turn over the watch and head to your
berth for a well-earned rest.
Click to view 29 June Deck Log
41
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Q7
Underway
Practice Cruise – Part 2
End Of
Homework
Q&A
Junior Navigation
Chapter 13
45