Magnetic Heading; Course Over Ground - Velocitek Prostart Manual

Modes 13

Magnetic Heading

With the addition of a solid-state geomagnetic (compass) sensor, the ProStart's factory default direction
output is magnetic heading. The default heading is magnetic heading of the device expressed in degrees
with 360˚ being North.
When the ProStart's direction output is set to magnetic heading, the ProStart's top line will show
compass heading with three digits at all times. Leading zeros will be displayed when the heading is not
three digits, i.e. eleven degrees will be shown as 011° and three degrees will be shown as 003°.
See the Configuration section on page 20 for instructions on changing the ProStart's direction output
from magnetic compass to course over ground.

Course Over Ground

The user has the option to substitute Course Over Ground (COG) in place of Heading. COG is calculated
by the GPS unit by measuring the Doppler shift in GPS signals.
Either true or magnetic COG can be displayed by entering your local magnetic declination into the
ProStart. "True COG" is referenced to true north. "Magnetic COG" is referenced to the local magnetic
north. When using a magnetic compass in conjunction with the ProStart, displaying COG in degrees
magnetic can be useful since both measurements will be referencing magnetic north.
By default, COG is displayed in degrees true. To display COG in degrees magnetic the local magnetic
declination must be entered in the device settings. See the Configuration section on page 20 for
instructions on entering your local magnetic declination into the ProStart.
The ProStart displays COG only when your speed is greater than 0.5 knots. If your speed is less than 0.5
knots the ProStart will display '- - -' for COG regardless of which direction you are moving.
Unlike the magnetic heading from a compass, COG requires movement. COG depends only on the
direction you are moving, not the direction the device is pointing. If your ProStart is configured to display
COG, the ProStart will give you accurate COG information regardless of the orientation in which it is
mounted on your boat (i.e. mounted on the sides of a boom, or a tacking bracket on a Moth).
When the ProStart's direction output is set to COG, the ProStart's top line will show COG with no leading
zeros, i.e. eleven degrees will be shown as 11° and three degrees will be shown as 3°.