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NAVIGATION > MOBOARD > Flashcards

MOBOARD Flashcards

(111 cards)

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1
Q

Advance

A

The distance a vessel moves in its original direction after the helm is put over

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2
Q

Apparent Wind

A

The speed and true direction from which the wind appears to blow with reference to a moving point.

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3
Q

Circle Spacing

A

The distance in yards between successive whole numbered circles. Unless otherwise designated, it is always 1000 yards.

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4
Q

Cone of Course

A

Mathematically calculated limits, relative to datum, within which a submarine must be in order to intercept the torpedo danger zone

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5
Q

Course

A

Direction of actual movement relative to true north

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6
Q

Datum

A

The last known position of an enemy submarine at a specified time. (Lacking other knowledge this is the position and time of torpedoing)

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7
Q

Direction

A

The position of one point in space relative to another without reference to the distance between them

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8
Q

Direction of Relative Movement

A

(DRM) the direction of movement of the maneuvering ship relative to the reference ship; the direction of the relative movement line

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9
Q

Distance Circles

A

Circles concentric to the formation center, with radii of specified distances, used in the designation of main body stations in a circular formation. Circles are designated by means of their radii, in thousands of yards from the formation center. Thus, circle 5 is a circle whose radius is 5000 yards from the center, while circle 7.2, is a circle 7200 yards from the formation center

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10
Q

Distance is Relative Movement

A

(MRM) the distance along the relative movement line between any two specified points or times

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11
Q

Fictitious Ship

A

An imaginary ship, presumed to maintain constant course and speed, substituted for a maneuvering ship which alters course and speed

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12
Q

Formation Axis

A

An arbitrarily selected direction from which all bearings used in the designation of main body stations in a circular formation are measured. The formation axis is always indicated as a true direction from the formation center

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13
Q

Formation Center

A

The arbitrarily selected point of origin for the polar coordinate system, around which a circular formation is formed. It is designated station zero

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14
Q

Formation Guide

A

A ship designated by the OTC as guide, and with reference to which all ships in the formation maintain position. The guide may or may not be at the formation center

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15
Q

Geographical (navigational) plot

A

A plot of the actual movements of objects (ships) with respect to the earth

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16
Q

Limited Lines of Approach

A

Mathematically calculated limits, relative to the force, within which an attacking submarine must be in order that it can reach the torpedo danger zone

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17
Q

Maneuvering Ship

A

Any moving unit set up in the problem except the reference ship

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18
Q

Missile Danger Zone

A

An area which the submarine must enter in order to be within maximum effective missile firing range

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19
Q

Range

A

Distance between ships

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20
Q

Reference Ship

A

The ship to which the movement of others is referred

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21
Q

Relative Distance

A

(MRM) The distance along the relative movement line between any two specified points or times

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22
Q

Relative Movement

A

The motion of one ship relative to another

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23
Q

Relative Movement Line

A

The locus of positions occupied by the maneuvering ship relative to the reference ship

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24
Q

Relative Plot

A

The plot of the positions occupied by the maneuvering ship relative to the reference ship

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25
Relative Vector
A velocity vector which depicts the relative movement of an object (ship) in motion with respect to another object (ship), usually in motion
26
Relative Wind
The speed and relative direction from which the wind appears to blow with reference to a moving point.
27
Screen Axis
An arbitrarily selected direction from which all bearings used in the designation of screen stations in a circular formation are measured. The screen axis is always indicated as a true direction from the screen center
28
Screen Center
The selected point of origin for the polar coordinate system, around which a screen is formed. The screen center usually coincides with the formation center, but may be a specified true bearing and distance from it
29
Screen Station Numbering
Screening stations are designated be means of a station number, consisting of four or more digits. The last three digits are the bearing of the screen station relative to the screen axis, while the prefixed digits indicate the radius of the distance circle in thousands of yards from the screen center
30
Speed of Relative Movement
(SRM) the speed of the maneuvering ship relative to the reference ship
31
Speed Triangle
The usual designation of the vector diagram when scaled in knots
32
Station Numbering
Positions in a circular formation (other than the formation center) are designated by means of a station number, consisting of four or more digits. The last three digits are the bearing of the station relative to the formation axis, while the prefixed digits indicate the radius of the distance circle in thousands of yards. Thus station 4090 indicates a position bearing 90 degrees relative to the formation axis on a distance circle with a radius of 4000 yards from the formation center. Station 10.2340 indicates a position 10200 yards from the formation center bearing 340 degrees relative to the axis
33
Timeline
A line joining the heads of two vectors which represent successive courses and speeds of a specific unit in passing from an initial to a final position in known time, via a specified intermediate point. This line also touches the head of a constructive unit which proceeds directly from the initial to the final position in the same time. By general usage this constructive unit is called the fictitious ship. The head of its vector divides the time line into segments inversely proportional to the times spent by the unit on the first and second legs. The time line is used in two course problems
34
Torpedo Danger Zone
An area which the submarine must enter in order to be within maximum effective torpedo firing range
35
Transfer
The distance a vessel moves perpendicular to its initial direction in making a turn
36
True Vector
A velocity vector which depicts actual movement with respect to the earth
37
True Wind
True direction and force of wind relative to a fixed point on the earth
38
Vector
A directed line segment representing direction and magnitude
39
Vector Diagram
A graphical means of adding and subtracting vectors. When the vector magnitude is scaled in knots, this diagram is usually called Speed Triangle
40
Velocity Vector
A vector the magnitude of which represents rate of movement; a velocity vector may be either true or relative depending upon whether it depicts actual movement with respect to the earth or the relative movement of an object (ship) in motion with respect to another object (ship)
41
Wind Direction
The direction from which the wind blows
42
Wind Speed
The rate of motion of air
43
CPA
Closest Point of Approach
44
CWC
Composite Warfare Commander
45
DRM
Direction of Relative Movement
46
LLSuA
Limited Lines of Submerged Approach
47
LLQA
Limited Lines of Quiet Approach
48
LLSnA
Limited Lines of Snorkel Approach
49
LLSA
Limited Lines of Surface Approach
50
M
Maneuvering ship designation
51
MRM
Miles of Relative Movement
52
OTC
Officer of Tactical Command
53
R
Reference ship designation
54
RML
Relative Movement Line
55
SRM
Speed of Relative Movement
56
Relative Motion
Is motion with respect to an arbitrarily selected object
57
True Motion
Is movement with respect to the earth
58
e
Point of origin; fixed with respect to the earth
59
er
Reference ship vector designation
60
em
Maneuvering ship vector designation
61
rm
Relative movement vector designation representing SRM and DRM; always plotted in the direction M1 - M2
62
What are two types of bearings for indicating the direction of any object from another?
True Bearing Relative Bearing
63
What are two points of reference are used to indicate bearings that never change?
The geographic North Pole for true bearing and the bow of our ship for relative bearing
64
True Bearing
Is the angular measurement between true north and the line of sight or line of bearing to an object. Always measured clockwise from north
65
Relative Bearing
Is the angular measurement between own ships head and the line of bearing to an object. It’s always measured clockwise from own ships head to the line of bearing or line of sight
66
What is the formula for calculating for True Bearing?
TB = RB + SH ``` TB = True Bearing RB = Relative Bearing SH = Ship Heading ```
67
What is the formula for calculating REaltive Bearing?
RB = TB - SH ``` RB = Relative Bearing TB = True Bearing SH = Ship Heading ```
68
What are your cardinal points?
North South East West
69
What are your intercardinal points?
Northwest Northeast Southwest Southeast
70
What is it called if it bears 000 degrees relative?
Dead Ahead
71
What is it called if it bears 045 degrees relative?
Broad on the Starboard Bow
72
What is it called when it bears 090 degrees relative?
Broad on the Starboard Beam
73
What is it called when it bears 135 relative?
Broad on the Starboard Quarter
74
What is it when it is bearing 180 degrees relative?
Dead Astern
75
What is it when it bears 315 degrees relative?
Broad on the Port Bow
76
What is it when it bears 270 degrees relative?
Broad on the Port Beam
77
What is it if it bears 225 degrees relative?
Broad on the Port Quarter
78
Target Angle
Is the relative bearing of your ship as seem from the target
79
What is the formula for Target Angle?
TA = TB + 180 - TC ``` TA = Target Angle TB = True Bearing 180 = Reciprocal Bearing TC = Targets Course ```
80
True or False Motion is simply the movement of an object from one point to another
True
81
The change in positions in relations to a fixed reference point on Earth is known as _____________ movement.
True or actual
82
The movement that takes place between two ships when one or both are moving is known as ________________ movement
Relative
83
Which of the following is an example or relative motion? ``` A. A train traveling from Miami to Chicago B. A speeding auto passing a motorcycle C. A ship sailing around the world D. A person walking 5 miles E. All the above ```
B
84
Your own ship is on a course of 280 degrees true and lookout reports a contact bearing 350 degrees relative. What is the true bearing of the contact?
270 degrees true
85
Your course is 70 degrees true. Lookout report has a contact broad on the port quarter. What is the true and relative bearing of the contact?
295 degrees true/225 degrees relative
86
What is the reciprocal bearing of a contact that bears 260 degrees true?
080 degrees true
87
A contact bears 020 degrees true from own ship and is on course 270 degrees true. What is the target angle?
290 degrees true
88
The PPI scope is a presentation of _______________
Relative Motion
89
What is the formula to find a vessels speed?
S = D / T
90
If a ship travels 1500 yards in 5 minutes, what is it’s speed?
9kts
91
What is the formula for finding a ships distance?
D = S x T
92
If a ship travels 10 kts for 21 minutes, what is the distance will it have traveled?
7000 yards
93
What is the formula for figuring out time?
T = D / S
94
How long does it take a ship to travel 11200 yards at 14 kts?
24 minutes
95
What is the specific purpose of a maneuvering board?
It is specifically designed for solving problems relative motion
96
You are using the 2:1 scale for measuring distance. Each dot on the maneuvering board represents how many yards?
200
97
What is the distance scale would give you the largest plot of a contact having a range of 28800 yards?
3:1
98
What is the speed of a contact that travels 24000 yards in 40 minutes?
18kts
99
A contact traveling 12 kts in 25 minutes will travel a distance of ____________ yards.
10000
100
A contact that traveled at a speed of 16 kts and reached a distance of 32000 yards made its destination in ________________ minutes
60 minutes
101
The length of er vector represents own ships ______________
Speed
102
The initial mark of a contract is called _____________
M1
103
CBDR
Constant Bearing Decreasing Range
104
PAO
Past and Opening
105
What is determined by this paralleling a contacts relative movement line (RML) to the center of the maneuvering board?
DRM
106
The measured distance and elapsed time between the marks M1 and M2 determines the _______________
SRM
107
True or False All vectors originate from the center of the maneuvering board?
True
108
The direction of relative movement (DRM) and the r-m vector are always drawn __________________
The same as the e-r vector
109
In the vector diagram, the direction of relative movement (DRM) and the speed of relative movement (SRM) determines the length and direction of the _______________ vector
r-m
110
Dead Time
Is the time between the time you decide to execute a maneuver and the actual time you begin the maneuver
111
MX
The point of execution for a maneuver on a MOBOARD

NAVIGATION (2 decks)

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