Chapter 2: Compass

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Chapter 2 Compass
Instructor Forrest Meiere
Selected Questions Study these for exam
PowerPoint Presentation by Forrest Meiere
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S2-4 Fastened to the gimbal is one or more
against which the dial
graduations can be read to determine the
direction of the vessel relative to the card.
Lubber's Lines
S2-6 During the mid-1920's an electronic compass
termed a compass was developed
for aircraft. In recent years, this has become
available to the mariner.
fluxgate
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S2-7 The modern magnetic compass is highly
sensitive and is able to align itself with
, such as the
earth's magnetic field.
weak magnetic fields
S2-8 However, the magnetic field aboard a vessel
is not solely due to the earth's magnetic field.
Other shipboard magnetic fields are caused by a
variety of items, including
.
see list in book No need to memorize this list,
just recognize some of the items if presented in
this context.
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S2-9 These additional fields also affect the
compass, with the result that the
of the vessel may differ from its
.
compass heading magnetic heading
deviation
S2-10 Simply put, is the
difference between the direction that the compass
actually points and the direction that it would
point if there were no local magnetic fields
aboard the vessel.
S2-12 Unlike variation, which depends solely on
the vessel's position, deviation varies with the
vessel's .
heading
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S2-15 A device for measuring relative bearings is
termed a .
pelorus
S2-16 The letter sequence TVMDC is used to
describe the sequence of starting with a
course, correcting for __________ to
calculate a course, and finally
allowing for to calculate a
course.

True Variation
Magnetic Deviation
Compass
S2-17 When converting from a true course to a
compass course (i.e. uncorrecting), westerly
variation and deviation are to be .
added
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S2-18 When converting from a compass to a true
course (correcting), variation and
deviation are to be and
variation and deviation are to be subtracted.
East
added West
S2-19 It is important to remember that compass
readings are most accurate only when the vessel
is level,
, and maintaining a constant
course..
traveling at a constant speed
No need to memorize these constraints or the
corrections in S2-19 S2-20 just recognize them
in a question
End of Questions
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P2-1 T V M D C 29W 287C
258M
P2-2 T V M D C 060M 056C
4E
P2-3 T V M D C 9W
4W 045C
032 041M
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P2-4 T V M D C 013 9W
022M
P2-5 T V M D C 022M 4E
018C
P2-6 T V M D C 013 9W 022M
4E 018C
270R 283 (True Bearing to Vessel)
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P2-7 through P2-16 Variation 015E
. T V M D C 15E
P2-7 T V M D C 15E 035C
055 040M 5E
P2-8 T V M D C 15E 135C
149 134M 1W
P2-9 T V M D C 149 15E
134M 1W 135C
035R 184 (True) Bearing to Buoy
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P2-10 T V M D C 15E 285C
297 282M 3W
090R 387 (Subtract 360) 027 (True)
Lighthouse Bearing
P2-11 T V M D C 027 15E
180 to find reciprocal 207 (True)
Reciprocal Bearing
T V M D C 207 15E
192M Reciprocal
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P2-12 T V M D C 15E 185C
196 181M 4W
285R 481 - 360 121 Bearing
180 (to find reciprocal) 301 (True)
Reciprocal
P2-13 T V M D C 110 15E
095M 3E 092C
285R Buoy 6 Bearing 002C lt 362C
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P2-14 T V M D C 200 15E
185M 4W 189C
P2-15 T V M D C 15E 145C
158 143M 2W
P2-16 T V M D C 15E 323C
338 323M 0
End of Problems