Flashcards in Exam 3 Deck (40):
Sailings is using math to solve for
Courses and distance from one point to another, and point of arrival when point of departure, course, and distances are known.
What are the five types of sailings?
1 = plane sailing
2 = parallel sailing
3 = mid latitude sailing
4 = mercator sailing
5 = Great circle sailing
When used in sailings, the word departure refers to
East to west distance in miles, or west to east distance in miles
One minute of latitude equals
One minute of longitude
Does not equal 1 mile anywhere except at the equator
While navigating off of the equator the difference of longitude between two points, in minutes of longitude
Does not equal the east to west distance in miles
Departure is written as what?
What type of functions are used in sailings?
Accuracy in navigation problems is to the nearest
10th of a mile or 10th of a minute of longitude or latitude
A 10th of a mile =
(6076.1÷10 = 607.61 feet)
How many different angles does each group of trig functions contain?
All five types of sailings are used to determine
Course and distance
Plane sailings is used to find
The difference of latitude and departure
Parallel sailings are used to find
Longitude of arrival
Mid latitude and Mercator sailings are used to find
Latitude and longitude of arrival
Great circle sailings are used to find
The initial course and distance, latitude and longitude of Vertex, and points along the great circle route
Plane sailings use simple plane geometry to solve for the parts of a
And assumes that the earth is
Right triangle; flat
Why can’t plane sailings solve for difference of longitude?
Because the earth is a sphere
Course angle (off 000°/360° or 180°)
Parallel sailing was used prior to accurate When it wasn’t possible to determine
Prior to accurate chronometers, ships would run north or south to latitude of destination, then head east or west to the actual destination adjusting course as needed.
What is parallel sailing mainly used for today?
As a component part of mid lat sailing
Difference in longitude in minutes
In reference to parallel sailings the course will either be
Due West (270°) or East (090°)
Mid latitude sailing is a combination of
Plane and parallel sailings
With regards to midlatitude sailings, the plane sailing is used to
Find the difference of latitude and departure when we know course in distance, or find a course in distance when we no difference of latitude and departure
With regards to mid latitude sailings, parallel sailing is used to
Convert departure to difference of longitude or vice versa
The latitude that is used in parallel sailing part of midlatitude sailing is the
Of the latitude of departure and the latitude of arrival
Do not use mid latitude sailing if you
Cross the equator
If you are crossing the equator it’s best to use
In Mercator charts the course is measured by the angle between the
Meridian (longitude line) and the coarse line
How is distance measured on the Mercator charts?
With dividers on the latitude scale at the left or right side of the chart
One minute of latitude =
One nautical mile
Can difference of longitude be used as miles?
Meridional parts and D-Lo in minutes of longitude are used to
Find the course angle
The length of the arc of a meridian between equator and a given parallel on a Mercator chart expressed in units of one minute of longitude at the equator.
The largest circle that can be drawn on the surface of a sphere and the shortest distance along the surface between any two points.
Great circle sailing
A great circle on the earth will be any
Meridian and the equatorial belt