Nav Aids
The memory aid "Red Right Returning" is used for this buoyage system
IALA B
The great circle that divides Earth into the Northern and Southern Hemispheres.
Equator
The three reference systems used for bearings.
True, magnetic, relative
A low pressure system with rising air in the Northern Hemisphere is called a
Cyclone, Depression, or Hurricane
The three functional segments of GPS
Space, user, control
***DOUBLE JEOPARDY***
A light with a period of 5 consecutive seconds off and 5 consecutive seconds on is defined as
Isophase
On a Mercator projection, this plots as a straight line and is commonly used in navigation.
Rhumb line
Depth-measuring system that can read in feet or fathoms.
Fathometer or Echo Sounder
This front occurs when a cold air mass overtakes a warm air mass and forces the warm air upward.
Occluded front
The minimum number of satellites needed for a full navigation solution, including altitude
4
This mark indicates the approximate true bearing of safe water from the danger it marks.
Cardinal mark/system
The projection where great circles plot as straight lines (useful for planning long ocean routes).
Gnomonic projection
*** DOUBLE JEOPARDY***
This instrument is used to determine precise ranges between ships in formation using a known height.
Stadimeter
**DOUBLE JEOPARDY**
Standard sea-level atmospheric pressure. (Millibars or inches of mercury)
29.92 in HG or 1013.2mB
This GPS threat falsifies data to masquerade as a legitimate signal.
Spoofing
Horizontal red and black bands; marks a danger with navigable water all around it.
Isolated Danger mark
The U.S. Navy’s standard chart/GPS reference datum.
WGS 1984
“True speed” is also called this; common GPS output.
Speed over ground
This time of day defines when the tide “pauses” briefly at high water or low water with no change in level.
The stand
The amount of transfer for a 180 degree turn defines this key ship characteristic
Tactical Diameter
A lateral buoy with alternating red/green identifying the best channel for use
Bifurcation buoy or preferred-channel marker
Distortion on a gnomonic projection is least severe at this point
Center of the point of tangency or center of the projection
This instrument provides true and relative bearings simultaneously on a gyrocompass by lining up sight vanes.
Azimuth circle or a telescopic alidade
As the tide falls and water flows away from the shore, this is what the tidal current is called
Ebb current
This GPS vulnerability is the “intentional alteration and degradation” of accuracy to limit hostile use.
Selective Availability