Ch 1-4 Flashcards
What six (6) things should a navigator consider concerning the accuracy of a chart when using it for the first time?
- Who made the chart?
- How old is survey data?
- Is the chart up to date?
- Does the chart cover an area that is subject to change?
- Are the sounding lines thick or thin?
- Is the scale of the chart suitable for the area being navigated?
A ___________ chart is used for coastwise navigation outside most of the coastal reefs, shoals, banks, etc. It is the second smallest scaled chart.
General Chart
What is defined as: the intersection of the Earth’s surface with a plane that does not pass through the center of the Earth?
A Small Circle
What is a line of longitude called?
A Meridian
A Mercator chart that is based on a cylinder tangent to the Earth at some great circle other than a meridian or the equator is referred to as what?
oblique Mercator projection
What is the datum used most commonly on American charts for the height of objects on land?
Mean High Water
A _________ _________ is a line that crosses all meridians at the same angle
Rhumb Line
____________ is the difference between Compass North and Magnetic North.
Deviation
A projection that depicts the Earth’s surface as formed on a series of cones tangent to the Earth is called?
Polyconic projection
What is a line on the surface of the Earth that is defined by the intersection of the Earth’s surface with a plane passing through the center of the Earth?
A Great Circle
The largest scale chart is also the chart that shows the greatest detail and is called a _________ _________.
Harbor Chart
What is the name for the 3rd smallest scaled chart?
Coastal Chart
The __________ of a chart is the ratio of a given distance on the chart to the actual distance on the Earth that it represents.
Scale
What is the formula for finding the circumference of a circle?
Pi x diameter
On a Mercator projection, _____________ remain the same distance apart on the entire chart, but ____________ get farther apart as one goes from the equator toward the pole.
> meridians
> parallels
What is the ditty for going from Magnetic North to True North?
Can Dead Men Vote Twice At Elections?
The depth of water on a nautical chart is referred to as?
Soundings
What is the datum most commonly used on American charts for depth?
Mean lower low water
What is the circumference of the Earth at the equator?
21,639 nm
The smallest scale chart used for nautical navigation is referred to as a?
Sailing Chart
What is a map used for navigation called?
A chart
The most commonly used projection of the Earth’s surface is a called a _____________ projection
Mercator
For navigation close to the shore and inside the coastal reefs, shoals or banks a ___________ chart is used.
Coastal Chart
What is the term for the known reference level given to the depth of water at a given location?
A datum
What is the circumference of the Earth through the poles?
21,567 nm
The difference in direction between true north and magnetic north is called?
Variation
What is the length (in feet) of a Nautical Mile?
6076.1 ft
A _________ _________ is the shortest distance between two points on the Earth.
Great Circle
The combination of magnetic variation and deviation is called?
Compass error
What is the ditty for finding Magnetic North from True North
True Virgins Make Dull Companions At Weddings
What is the maximum longitude that any place can have?
180 degrees
The ___________ ____________ _____________ makes charts of American waters.
National Oceanic Service (NOS)
A ___________ _______________ projection is based on the features on the Earth’s surface being transferred onto the surface of a cone which intersects the Earth at two small circles.
Lambert Conformal projection
A ____________ projection is one in which the features on the Earth’s surface are projected onto a plane which is tangent to the Earth at a single point.
Gnomonic
A projection that is based on points on the Earth’s surface being projected onto a cone that is tangent to the Earth is called a?
Conic Projection
A Mercator chart that is based on a cylinder tangent to the Earth at a meridian instead of at the equator is called?
a transverse Mercator projection
What is the term used to describe the shape of the Earth?
Oblate Spheroid
What is described as “based on the concept of points on the Earth’s surface being projected onto a cylinder which is tangent to the Earth?”
A Mercator Projection
The angular difference between True North and the direction indicated by the north point of the compass is?
Compass error
Who invented the mercator projection?
Gerhard Kremer
A ________ ________ is a course measured from either north or south toward either east or west, and it cannot exceed 90 degrees.
Course Angle
What is the maximum latitude that any place can have?
90 degrees
The period of _________ years that tides are measured in order to establish a tidal datum is called a ____________ _________.
> 19 years
> Metonic Cycle
What is it called if the point of tangency on a gnomonic chart is at the north or south pole?
Polar Gnomonic Projection
A ___________ is defined as the angle between North and the direction in which the ship is moving.
Course
What is a line of latitude referred as?
A Parallel
One ___________ mile equals one _________ of _________.
> nautical
> minute
> latitude
What agency is responsible for making charts of foreign waters?
National Geospatial Agency (NGA)
What is the value of Pi
3.1416
