Furuno GP-33, User Manual

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7. OTHER FUNCTIONS
7-2
TTG/ETA SPD
To calculate time to go and estimated time of arrival, enter your speed as below.
-Auto (GPS calculated speed)
1. Press X and ENT in order.
2. Enter the speed average (1 to 999 sec.) to use, and press the ENT key.
-Manual (Speed calculated manually)
1. Press X and ENT in order.
2. Enter speed (1 to 999 knot), and press the ENT key.
7.2 GPS Setup Menu
The GPS Setup menu smooths position and course, averages speed, applies position
offset, and deactivates unhealthy satellites.
Datum
Your unit is programmed to recognize most of the major chart systems of the world.
Although the WGS-84 system, the GPS standard, is now widely used other categories
of charts still exist. Select the same datum which is used in your nautical charts. Select
WGS84 (default setting), WGS72 or Other (required the datum number entering).
Navigation
When you set a destination, the equipment displays the range, bearing and course to
that destination. Range and bearing are calculated by the Great Circle or Rhumb Line
method. Route total distance is also calculated. Cross-track error is only calculated in
the Rhumb Line method.
Rhumb line: This method calculates the range and bearing between two points drawn
on a nautical chart. Since the bearing is kept constant it is ideal for short-range navi-
gation.
Great circle: This course line is the shortest course between two points on the surface
of the earth, like stretching a piece of string between two points on earth. Frequent
bearing changes are required to navigate by this method. For long-range navigation,
divide the Great Circle route into several routes, and navigate each route by Rhumb
Line.