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Navigation 1 Quiz 1
Quiz 1
30
Other
Not Applicable
03/13/2005

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Term
What is an LOP?
Definition
A line of position; A single observation that does not establish a fix but does mean that the ship’s position is somewhere along that line.
Term
How do you label an LOP?
Definition
After the LOP is drawn from a Navaid, a four digit time must be written above and parallel to the Line of Position.
Term
Where do you get LOP's from?
Definition
You can shoot a visual LOP, or get an LOP from a radar.
Term
What is the most accurate type of LOP?
Definition
A visual range LOP (when two known objects line up).
Term
How are visual bearings measured?
Definition
In any way, but they have to be converted to true before they can be plotted on the chart.
Term
What is a fix?
Definition
The point where two or more LOP’s cross. This indicates the ship’s position on the chart.
Term
How do you label a fix?
Definition
Use the four digit time next to the fix, it should be parallel to the bottom of the chart. The times of the individual LOPs are not written on each LOP.
Term
What shape is a visual fix when plotted on a chart?
Definition
A Circle.
Term
What shape is an electronic fix when plotted on a chart?
Definition
A triangle.
Term
What shape is used to plot the ship's estimated position on a chart?
Definition
A square.
Term
What shape is used to plot the dead reckon position advanced from the previous fix on a chart?
Definition
A half circle on a line.
Term
What is the optimum seperation of LOP's
Definition
1800 / number of LOP’s, for example if there are three LOP’s then optimum separation is 60 degrees.
Term
How do you shoot bearings for bearing LOP's?
Definition
“Beam to Bow”.
Term
How do you shoot bearings for range LOP's?
Definition
“Bow to Beam”.
Term
What is dead reckoning?
Definition
the process of determining a ship’s approximate position by applying, from its last known position, a vector or a series of consecutive vectors representing the true courses steered and the distance run as determined by the ship’s speed and time, without considering the effects of wind and
current.
Term
What are the 6 rules of dead reckoning?
Definition
1-Plot a DR Position Every Hour on the Hour. 2-Plot a DR Position at Every Course Change. 3-Plot a DR Position at Every Speed Change.4-Plot a DR Position for Every Line of Position (LOP). 5-Plot a DR Position for Every Fix or Running Fix. 6-Plot a new Course Line with Every Fix or Running Fix.
Term
What is the 3 minute rule?
Definition
The distance of travel of a ship in yards in three minutes is equal to its speed in knots multiplied by 100.
Term
What is the 6 minute rule?
Definition
The distance of travel of a ship in nautical miles in six minutes is equal to its speed in knots divided by 10.
Term
What is a tide?
Definition
The vertical rise and fall of a body of water.
Term
What is a Semidiurnal tide?
Definition
two high and two low each day
Term
What is a diurnal tide?
Definition
one high and one low each day.
Term
What is a current?
Definition
The horizontal movement of water, and classified as either tidal or non-tidal.
Term
What is a flood current?
Definition
A tidal current that flows toward shore as result of a rising tide.
Term
What is an ebb current?
Definition
Tidal current that flows away from shore as a result of a falling tide.
Term
What is the most notable of non-tidal currents?
Definition
The Gulf Stream.
Term
What does a current do to a ship?
Definition
Causes the ship to depart from its DR.
Term
What is current sailing?
Definition
The process of determining the
effect current has on your vessel and allowing for it when determining courses and speeds required to
correct or compensate for such currents (speed and direction).
Term
What are the 2 main components of a current?
Definition
Set and drift.
Term
Which phase if used in voyage planning
to select a course to make good your desired track using an estimated current?
Definition
The Pre-Sailing Phase.
Term
Which phase is used while navigating by
comparing the DR position to the position of the fix of the same time. Course and speed alterations are made based upon the calculated set and drift?
Definition
The Piloting Phase.
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