DR Sailing Flashcards

1
Q

What is DR sailing

A

determining a ship’s approximate position by applying from it’s last known position, a vector or series of consecutive vectors representing the run that has since been made, using only courses steered and distance run

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2
Q

How can you get a fix

A

soundings, vertical and horizontal
angles, bearings, and ranges

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3
Q

Heading (SH)

A

direction in which a vessel points at any instant, Ships Head

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4
Q

Course (C)

A

direction in which a vessel is to be steered, or is being steered

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5
Q

Speed (S)

A

engine ordered rate of travel

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6
Q

How do you measure course made good and speed made

A

measured fix to fix

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7
Q

How many LOPs do you need to get a fix

A

2

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8
Q

What is a running fix

A

position determined by the intersection of two (or more) LOP’s established at different times

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9
Q

Estimated position

A

The most probable position of a vessel based upon available information or information of questionable accuracy

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10
Q

What is the most accurate LOP

A

observing two or more objects in a line or visual ranges

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11
Q

What should you do if there is ambiguity in the LOP taken for a fix

A

assume vessel is in worse position possible and make recommendation accordingly

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12
Q

If two LOPs are used how far apart should they be

A

90 degrees

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13
Q

If three LOPs are used for a fix how far apart should they be

A

120 degrees

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14
Q

What size chart should you plot your DR

A

Largest scale chart available

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15
Q

In restricted waters how often do you get a fix

A

Every three minutes

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16
Q

In less restricted waters how often do you get a fix

A

Every 15 minutes

17
Q

For how long can you use a LOP for a running fix

A

30 minutes or less

18
Q

What is the secret to success for dead reckoning

A

practice and neatness

19
Q

What do you need if you want to figure out when a light will be lost from site

A

computed visibility

20
Q

What is the maximum distance a light can be seem in the meteorological conditions in immediate vicinity

A

Computed visability

21
Q

What is nominal range

A

maximum distance a light can be seem in clear weather

22
Q

what does the light list have

A

information for lights and buoys in US

23
Q

What does list of lights have

A

information for lights and buoys in international/foreign waters

23
Q

What is the three minute rule

A

distance traveled in yards in three minutes
ships speed in knots x 100

24
What is the 6 minute rule
distance traveled in miles in 6 minutes
25
What is a paper computer
Logarithmic speed time distance scale
26
What is a nautical slide ruler
inexpensive plastic device used for rapid solution for time speed distance problems
27
Six rules for dr plotting
plotted hour on the hour every course change every speed change every fix or running fix if single line of position is obtained new course line plotted for fix or running fix
28
How many intervals will you extend a DR or course line
two fix intervals
29
What is an EP considered
midway between a good running fix and a unsubstantiated DR position
30
Dangers bearing ahead and to the left of the track are labeled? and the right?
NMT NLT
31
If you do not have a sextant what else can you use to get an angle
position finder
32
How often do you check your gyro error
once daily
33
What can a single LOP provide
Cannot provide position but can give useful negative information