TERNAV2 (PRELIM) Flashcards
Any object that can be easily identified and is used as a reference point to determine your position
Landmark
Natural Landmark
mountains, coastlines , islands , etc
Landmark can be
Natural Landmark and Man made Landmarks
Man made Landmarks
lighthouses, bridges,towers, buildings
The objects, devices, or systems that is used by the mariner to navigate safely through the waterways
Aids to Navigation
It indicates the areas of potential hazards to navigation
Aids to Navigation
It indicates the safe waters and navigable channels
Aids to Navigation
It provides a reference point to assist the mariner to navigate safely.
Aids to Navigation
A structure that emits a light to serve as an aid to seafarers
Lighthouse
It marks dangerous coastlines, shallow waters, rocks, wrecks, and safe entries to harbors
Lighthouse
Floating devices that are anchored to the seabed or moored in place.
Buoys
It serves as a visual marker to indicate navigational hazards, and marks the safe and unsafe waters
Buoys
Types of Buoys
Lateral Buoy, Cardinal Buoy, Isolated Danger Buoy, Special Mark buoy, EMERGENCY WRECK MARKING BUOY, Daymarks,
buoys that indicates the edge of the channel
Lateral Buoy
Its is marked with a specific top mark, light signal, shape, and color
Lateral Buoy
buoy that indicates the position of a hazard and the direction of safe water
Cardinal Buoy
The direction of safe water is indicated by the cardinal direction( N, E , W, S ) relative to the mark.
Cardinal Buoy
buoy that indicates a navigational hazard and warns the vessel to keep away from the danger
Isolated Danger Buoy
It does not indicate the direction of safe waters
Isolated Danger Buoy
The top mark consists of two black spheres in a vertical line
Isolated Danger Buoy
It has an alternating horizontal black and red bands
Isolated Danger Buoy
Used to identify the areas with special features
Special Mark buoy
the nature of such areas can be found by consulting the charts or Sailing Directions
Special Mark buoy
may indicate spoil grounds, military exercise areas, recreational zones, boundaries of anchorage areas, cables and pipelines, Dead ends, mooring areas, protected areas, marine farms or aquaculture, oil wells,ODAS(Ocean Data Acquisition System) which gather information about wind speed, pressure, salinity and temperature
Special Mark buoy
It marks the position of a wreck or an unsurveyed danger
EMERGENCY WRECK MARKING BUOY
Unlike any other buoys, it is designed to provide a highly conspicuous visual and radio aid to navigation
EMERGENCY WRECK MARKING BUOY
fixed structure or buoy that has a distinctive color and pattern which provides a visual reference during hours of daylight
Daymarks
It is often positioned near navigational hazards or on land
Daymarks
A conspicuous device designed to attract attention to a specific location that can be used to navigate safely.
Beacons
They are commonly used in conjunction with other aids to navigation, such as buoys or daymarks.
Beacons
When interrogated by a radar, it automatically returns a distinctive signal
Beacons
is the determination of position by advancing a known position for courses and distances
Dead Reckoning
the method used to forecast where the vessel will be, knowing the true course and speed alone
Dead Reckoning
The position determined is called a
DR position.
From a known position, it is the line along which a vessel is steered
Course
It is indicated by a circle around a dot, with a time notation
Fix
A position obtained by crossing 2 or more LOPs ( Line of Position)
Fix
Factors to consider when plotting a DR
- Course* Speed* Time* Distance
A DR shall be plotted every
- Once an hour, on the hour* At every course (and/or speed) change* Any time a line of position is established* At every fix the DR plot should be reset, and a new DR plot begun
DR positions are always
estimates
Keep in mind that there are _ that you need to consider in determining the vessel’s position overtime.
external factors
external factors
- Wind* Currents* Tides
can affect the vessel’s drift, causing it to deviate from its intended course to steer
Strong winds and ocean currents
can have an impact on the vessel’s speed and direction
Change in the height of tide
requires adjustments in navigation to determine the vessel’s position accurately
external factors
It is the speed relative to the water or how fast the vessel is moving through the water
Speed Through the Water
The vessel’s speed REGARDLESS of the external factors
Speed Through the Water
It is the speed relative to the ground
Speed Over Ground
The vessel’s speed CONSIDERING the external factors
Speed Over Ground
ALWAYS USE _ FOR COLLISION AVOIDANCE
STW (SPEED THROUGH THE WATER)
The direction in which a vessel is heading relative to the water.*
Course Through the Water
The direction on which the vessel’s bow is pointing, REGARDLESS of the external factors
Course Through the Water
The direction in which a vessel is actually moving, relative to the ground.
Course Over Ground
It takes into account not only the heading, but also the external factors
Course Over Ground
It measures the vessel’s actual track.
Course Over Ground
The Earth when cut up horizontally at the middle would give rise to a
circle of diameter equal to that of the Earth itself (assuming that the Earth were a sphere).
The Earth if cut up anywhere else horizontally would produce
circles which were smaller in diameter than the central circle
are circles on a sphere whose plane passes through the centre of the sphere
Great Circles
The vertical Great Circles are called the
circles of Longitude, or more correctly they are termed the meridians of Longitude
The vertical circles are thus
not parallel to each other.
is the angular distance from the equator, measured northward or southward at the poles.at the equator to 90°along a meridian from 0°
Latitude
between two places on the same side of the equator is half the sum of their latitudes
middle or mid-latitude (midLat.)
is labeled N or S to indicate whether it is north or south of the equator.
Mid-latitude
the latitude of the point of departure
Lat1
the latitude of the point of arrival
Lat2
the latitude of the vertex of a great circle or the limiting latitude in a composite great circle.
Latv
the latitude of any point on a great circle
Latx
is the angular distance between the prime meridian and the meridian of a point on the earth, measured eastward or westward from the prime meridian through 180°.
Longitude (Long.)
It is designated east (E) or west (W) to indicate the direction of measurement
Longitude (Long.)
the longitude of the point of departure
Long 1
the longitude of the point of arrival
Long 2
the longitude of the vertex of a great circle
Long v
the longitude of any on a great circle
Long x
The meridian of London at Greenwich
Prime meridian
This is the reference point for all astronomical and time calculations
Prime meridian
has a longitude of 0° and the meridians eastward to it are given a designation of EAST and all meridians west of the prime are designated as WEST
Prime meridian
between two places is the angular length of arc of any meridian between their parallels
difference of latitude (DLat.)
It is the _ of the latitudes if the places are on the same side of the equator
numerical difference
It is the _ of the latitudes if the places are on opposite sides of the equator
sum
between two places is the shorter arc of the parallel or the smaller angle at the pole between the meridians of the two places.
difference of longitude (DLong)
The distance between two meridians at any parallel of latitude, expressed in distance units, usually nautical miles, is called
departure
The length of the arc of a meridian between the equator and a given parallel on a mercator chart, expressed in units of 1 minute of longitude at the equator
Meridional parts (MP)
the meridional parts of the point of departure
MP1
the meridional parts of the point of arrival
MP2
This difference is found by subtraction if the two parallels that are on the same side of the equator and by addition if on opposite sides.
Difference of Meridional Parts (DMP)
Also referred to as meridional difference
Difference of Meridional Parts (DMP)
The length of a line joining two places or positions on the surface of the earth, expressed in nautical miles
Distance (Dist)
The angular direction measured clockwise or counterclockwise from 000° through 090° or 180°
Course Angle (C)
The reference direction (north or south) will be the
prefix
the direction of measurement (east or west) will be the
suffix
Is the intersection of the surface of a sphere and a plane through the center of the sphere
Great Circle
It is the largest circle that can be drawn on the surface of the sphere and is the shortest distance, along the surface, between any two points on the sphere
Great Circle
The point of greatest latitude on a great circle is called the.
vertex
The arc of the great circle between the points of departure and arrival
Great Circle Track
the most commonly used map projections, particularly for navigation purposes
Mercator Chart
It is useful for navigation because it allows for easy plotting of a course using a straight line on the map that corresponds to a constant compass bearing
Mercator Chart
When using Mercator Charts, you have to consider the _ as you move away from the equator, towards the poles
distortion
is a type of map projection where all great circles are represented as straight lines
Gnomonic Chart* Also known as a gnomonic projection
