Humminbird NS25 Operation Manual page 68

The natural magnetic pole of the earth. This point is continually moving over time, and differs from
true north by several hundred miles. This is the point to which all magnetic compasses will point.
MAP DATUM
A datum is an initial set of numeric geometrical quantities used as a reference from which to
measure other quantities used to define a region. From this information a map is created. The
NS25 allows you to choose from a selected list of map datums or it will default to the most
commonly used map datum in your area.
NAUTICAL MILE
Unit of distance with one nautical mile equating one minute of latitude at the equator or about
6,000 feet.
NIMA INTERFACE (OUTPUT)
This communicate with autopilots, plotters, radar etc. The National Marine Electronics Association
has developed a standard for communication between electronic navigation instruments.
POSITION
There are two options available for the display of your position: LAT LON is the default setting., it
provides your position with reference to the standard coordinate positioning of latitude and
longitude. The other option is "Lorans". It allows position read-outs in reference to Loran stations,
the same way that Loran receivers work. The readout is in "time differentials" (TD's). This feature
is designed to appeal to long time users who have stored points of interest by reference to TD's.
While the NS25 can be configured to read-out in TD's, be aware that doing so requires a
complete understanding of the loran system, and the accuracy of position readouts is limited to
the accuracy of both the loran system and the receiver used to store the points.
POWER
Press POWER once to turn on the NS25. To turn it off, hold down the key for three seconds, until
the audible chirp is heard. This will prevent accidentally turning the unit off during normal
operation.
P-STOR
Stores your preset position as a temporary waypoint, or stores the position of the cursor when it is
in use.