Chapter 6: Piloting

1
Chapter 6 Piloting

• Instructor Forrest Meiere

All Questions and Problems from the Study Guide
PowerPoint Presentation by Forrest Meiere
2
S6-l. What distinguishes PILOTING from other
branches of navigation?
The
reference to charted landmarks, ATONs and depth
soundings.
S6-2. Why are LOPs drawn on buoys (floating
atons) to be treated with caution?
Buoys can
be sunk or off station. (Buoys can be moved and
the new position may not be on the chart being
used.)
3
S6-3. What is the proper way to label an LOP?
On its top with the time of observation (24 hour
system) and on the bottom with the bearing from
the vessel to the object.
S6-4. How can a relative bearing be used to plot
an LOP?
Add the relative bearing to the true heading to
obtain an LOP.
4
S6-5. How can a range be used to obtain an LOP if
no bearing was obtained for the range?
Extend the range until it crosses the course
line. As with any LOP, record the time the
alignment occurred on the top of the LOP
S6-6. A circle of position is based on a
measurement of distance to the charted object.
What methods of measuring distance are generally
available to the navigator?

1. RADAR
2. Measurement of vertical angle with a sextant
3. Range Finder

5
S6- 7. When using the height of an object printed
on the l2l0-Tr chart, what are the units used and
what is the reference (datum) for the measurement?
feet Mean High Water
S6-8. List six type of FIXES discussed in the
text.

• Cross Bearing b. Range and Bearing
• c. Two Ranges d. Two Distances
• e. Distance and Bearing of Object
• f. Passing close to a fixed Aid to Navigation.

6
S6-9. What factors can affect the accuracy of an
LOP?
a. Inaccurate measurement of relative
bearings b. Mathematical Errors c. Inaccurate
Compass Readings d. Inaccurate Plotting
S6-10. How are visual FIXES labeled?
A point with a full circle around it and the time
(in 24 hour format) parallel to the horizontal
base of the chart
7
S6-11. List the steps necessary to plot a running
fix.

• Allow for a time lapse between the 1st and 2nd
  bearing
• One LOP is advanced by moving it parallel to
  itself in the direction of the course line for
  the distance traveled. The intersection of these
  two LOPs is the Running Fix.
• A new dead reckoning plot is started at the
  position of the R FIX
• d. Avoid advancing an LOP more than 30 minutes

End of Questions
8
PROBLEMS
Use the 1210- Tr chart
and the deviation table in Lesson 2.
P6-1. With the object dead ahead (RB 000), plot
and label the following LOPs
P6-1 OBJECT TIME BEARING a. MONUMENT,
CUTTYHUNK I. 613 p.m. 330
1813/330
b. CUPOLA, NAUSHON I.(NE) 930 a.m. 012C
0930/000
9
P6-1 OBJECT TIME BEARING c. SPIRE,
CHILMARK, 1 00 p.m. 314C MARTHA'S VINEYARD
1300/298
d. SPIRE, GAY HEAD 1053 p.m. 168C MARTHA'S
VINEYARD
2253/150
e. WATER TOWER 1016 a.m. 157C WOODS HOLE
1016/140
f. TOWER 730 a.m. 288C GOOSEBERRY NECK
0730/270
10
P6-1 OBJECT TIME BEARING g.
TOWER 801 a.m. 358C GOOSEBERRY NECK
0801/345
h. BUTLER FLATS LIGHT 625 a.m. 334C NEW
BEDFORD
0625/320
i. NEW BEDFORD 625 a.m. 324C R TR (WNBH)
0625/309
11
P6-1 OBJECT TIME BEARING j. TOWER, WEST
ISLAND 328 a.m. 288C
0328/270
k. SOUTH TIP, PENIKESE I. 231 p.m. 039C
1431/030
l. RADAR TOWER midnight 1200 005C
MARTHA'S VINEYARD
0000/352
12
P6-2. Plot and label the following ranges
P6-2 TIME OBJECT (A) OBJECT (B) a. 215
a.m. GAY HEAD, SPIRE GAY HEAD LIGHT Alt
Gp Fl (3)(1) R 40 s
0215
b. 2 15 p.m. MARTHA'S VINEYARD CHILMARK
SPIRE RADAR TOWER
1415
c. 312 p.m. MARTHA'S VINEYARD LOOKOUT TOWER
AERO Rot W G
1512
13
P6-2 TIME OBJECT (A) OBJECT (B) d. 1223
a.m. WOODS HOLE DOME WATER TOWER
0023
e. 735 a.m. ROUND HILL POINT WINDMILL
TANK
0735
f. 835 p.m. NASHAWENA ISLAND MONUMENT
HOUSE
2035
g. 11 23 a.m. CUTTYHUNK ISLAND MONUMENT
LOOKOUT TOWER
1123
14
P6-2 TIME OBJECT (A) OBJECT (B) h. 628
p.m. CUTTYHUNK I. NASHAWENA I.
LOOKOUT TOWER MONUMENT
1828
i. 913 a.m. MARTHA'S VINEYARD MENEMSHAPOND
RADAR TOWER ENTRANCE LIGHT
0913
j. 1017 p.m. FALMOUTH TOWER STACK
2217
15
P6-3. Plot and label the following Circles of
Position

• OBJECT TIME DISTANCE(M)
• GAY HEAD 1015 p.m. 3.1
• Alt Gp PI (3) W (1) R
• 40 Sec 170 ft 17 M

2215 D 3.1
D3.7
0715 D 2.0
b. CUTTYHUNK ISLAND 715a.m. 2.0
LOOKOUT TOWER
0625 D 4.2
c. MARTHA'S VINEYARD 625 a.m. 4.2 LOOKOUT
TOWER
16
OBJECT TIME DISTANCE(M) d. GAY HEAD SPIRE
825 a.m. 6.5
0825 D 6.5
1428 D 5.0
e. MARTHA'S VINEYARD 228 p.m. 5.0
AERO Rot W G
f. NOMANS LAND 11 38 p.m. 5.2
NORTH TIP
2338 D 5.2
g. PENIKESE I. 1203 a.m. 3.2
SOUTH TIP
0003 D 3.2
17
OBJECT TIME DISTANCE(M) h. WOODS HOLE
315 p.m. 2.6 WATER TOWER
1515 D 2.6
1818 D 1.8
i. BUTLER FLATS LIGHT 618 p.m. 1.8
D3.7
j. GOOSEBERRY NECK 527 p.m. 1.9
TOWER
1727 D 1.9
1300 D3.7

• BUZZARD'S LIGHT 100 p.m. 3.7
• PI 2.5sec 101ft 22M HORN

18
P6-4. At 1030 p.m., while on a course of C231 at
10.0 kn, from Buoy "27" FIG 4 sec BELL, in
Vineyard Sound, you note a light flashing every
six seconds on the starboard beam (090R) when
your heading is 251C.
C231 S10.0
a. Draw the course line and label it
2230 321
b. Plot the bearing and label it
19
P6-5. While heading 251C, at 700 p.m. south of
PASQUE Island, you note a flashing green light
every four seconds off your port bow (315R). Plot
the bearing and label it.
1900 186
20
P6-6. The MONUMENT on NASHAWENA ISLAND can be
seen off the starboard bow (045R) while on
heading 25lC at 930 a.m. Plot the bearing and
label it.
0930 276
21
6-7 . On another day at 625 a.m., while running
C262C at S 10.0, you sight the CUTTYHUNK ISLAND
MONUMENT on the starboard beam over the vessel's
compass at 090R. At the same time you note that
the MONUMENT and the HOUSE on NASHA WENA ISLAND
are in range.
a. What is the compass bearing of the CUTTYHUNK
MONUMENT?
352C
b. Plot and label the FIX, and determine its
latitude and longitude
DOT WITHIN CIRCLE, 0625 L 41 22.8'N Lo 70
55.4W
22
6-8. Southeast of GAY HEAD on MARTHA'S VINEYARD
at 1527, you are barely making way, and you take
a bow bearing of 322C on GAY HEAD SPIRE. You then
turn the boat toward the AERO Rot W G beacon at
the airport on MARTHA'S VINEYARD and obtain a
bearing of 029C.
a. Plot and label these two LOPs and the
resulting FIX
1527 1527 307 019
DOT WITHIN CIRCLE, 1527
b. What is the position of the FIX?
L 41 15.7'N Lo 70 40.4'W
23
6-9. At 0625 you are between NASHAWENA ISLAND and
GAY HEAD and note that the MONU- MENT and HOUSE
on NASHAWENA ISLAND are in range. You also note
that the SPIRE and the light on GAY HEAD (Alt Gp
PI (3) W (1) R 40 sec, 170 ft 17 M) are in
range. Plot these two LOPs and plot and label the
FIX they form.
FIX label DOT WITHIN CIRCLE, 0625
What is the position of the FIX?
L 41 22.8'N Lo 70 55.4'W
24
6-10. At 0715, while on course ofC288C at ordered
speed of 10.0 to, you detect a strong PIP on the
RADAR at the NW tip of GAY HEAD, range 5.6M. You
also notice a good PIP about the center of
CUTTYHUNK ISLAND which you decide is the TOWER
and measure the range at 5.1M. Plot and label
these two LOPs and the FIX they determine.
DOT WITHIN CIRCLE, 0715
RADAR
a. FIX label
L 41 20.3'N Lo 70
57.5'W
b. Position
083
c. Bearing to PIP on GAY HEAD
012
d. Bearing to PIP on CUTTYHUNK
25
P6-11. While underway at 2215 on course C239C,
you take a RADAR distance (5.1M) and bearing
(082R) on the North tip of NOMANS LAND. Plot and
label the LOPs, determine and label the FIX, and
provide its position.
DOT WITHIN CIRCLE, 2215 RADAR
a. FIX label
L 4113.2'N Lo 70
043.2'W
b. Position
2215, 5.1
c. Range LOP
2215, 302
d. Bearing LOP
26
P6-12. While underway on C23l/Sl0.0 from Buoy
"27" PI G 4 sec BELL, approximately three miles
southwest of WOODS HOLE entrance in VINEYARD
SOUND, you take a bearing on the light at the
head of TARPAULIN COVE, NAUSHON ISLAND, PI 6 sec
78 ft 9 M, at bearing 090R at 5 15 p.m. At 533
p.m. you take a bearing on the light at GAY HEAD,
Nt Gp PI (3) W (1) R 40 sec, bearing 341R while
on course.
C231 S10.0
a. Plot and label the course line
1715 321
b. Plot and label the 515 p.m. LOP
27
P6-12. (Continued)
C231 S10.0
c. Plot and label the 533 p.m. LOP
1715-1733 321
d. Advance the 5 15 LOP to 533. Plot and
label.
e. Plot and label the RUNNING FIX
1733 R FIX
f. Position
L 41 24.7'N Lo 70
47.0'W
28
P6-13. Assume all the same facts as in problem
6-12 with the additional information that, over
this time period, at 530 p.m. a 2.5 kn current
is flowing in VINEYARD SOUND toward 231 true.
C231 S10.0
a. Plot and label the course line
1715 321
b. Plot and label the 5 15 p.m. LOP
29
P6-13. (Continued)
1733 212
c. Plot and label the 533 p.m. LOP
1715-1733 321
d. Advance the 5 15 LOP to 533. Plot and
label.
e. Plot and label the RUNNING FIX
1733 R FIX
L 41 24.0'N Lo 70 47.6'W
f. Position
30
P6-14. While underway on C251C/S 10.0 in VINEYARD
SOUND, you observe the light on GAY HEAD (Alt Gp
PI (3) W (1) R 40 sec) bearing 3l5R at 1030
a.m. Nine minutes later the light is abeam
(270R). Plot and label the RUNNING FIX and
determine its position.
1039 R FIX L 41 22.1'N Lo 70 51.4'W
31
P6-15. Continuing from the position determined in
6-14 above, establish a danger bearing using BUZ-
ZARDS LIGHT (PI 2.5 sec 101 ft 22M HORN) to clear
the Sow and Pigs Reef by .5 M. What are the true,
magnetic, and compass (ship's head) danger
bearings on the BUZZARDS LIGHT?
NLT 282T NLT 297M NLT 299C
32
P6-16. Departing at 611 p.m. from L 41 l8.8'N
Lo 70 5l.7'W, you are underway on C136C/S12.0.
At 640 p.m. the CHILMARK SPIRE on MARTHA'S
VINEYARD is observed to bear 236R while your
heading is l36C.
C120 S12.0
a. Plot and label the course line
b. Plot and label the 640 p.m. DR
DOT WITHIN SEMICIRCLE and 1840 at angle
33
P6-16. (Continued)
1840 356
c. Plot and label the SPIRE LOP
d. Plot and label an Estimated Position (EP) for
the 640 p.m. LOP observation and determine
its position
DOT WITHIN SQUARE EP L 41 15.9'N Lo 70
44.2'W
P6-17. Prove that an EP constructed from a DR
position and a single LOP is generally closer to
the true position than the DR position.
See discussion in Study Guide
End of Problems