RD Instruments Cobra-Tac, User Manual, Page: 14 / 62

Cobra-Tac User's Guide
page 8 RD Instruments
3.3.1 Initial position
The initial position is the latitude and longitude where the Cobra-Tac en-
ters the water at the beginning of a dive and begins tracking its position (see
“2.0 Accuracy,” page 5 ).
3.3.2 Magnetic Variation
The Cobra-Tac’s internal compass records magnetic heading. The magnetic
variation at the location is needed to correct to true heading. Magnetic
variation is declination.
3.3.3 Waypoints
A waypoint is a position in the water that the Cobra-Tac guides a diver to-
ward. An absolute waypoint is a latitude and longitude. A relative way-
point is a range and bearing from the previous position.
3.3.4 Missions
A mission is an underwater course consisting of up to 20 connect-the-dot
waypoints. An absolute mission contains absolute waypoints. A relative
mission contains relative waypoints. All waypoint positions in a mission
must be the same type.
The Cobra-Tac has four modes that allow a diver to navigate underwater in
various ways. Missions are for use in the
WAYPOINT NAV mode. In this
mode, a diver starts at an initial position, swims to waypoint 1, and then
waypoint 2, and so on.
Missions are intended to be reusable in many mission profiles. They may
be imported and exported as needed (see the
CobraWare User’s Guide).
3.3.5 Event Marks
An event is a latitude, longitude, and label where a diver has noted some-
thing of interest and used the Cobra-Tac to mark the position. The Cobra-
Tac requires the diver to label each event as either “NATURAL” or “MAN
MADE”. All events in Cobra-Tac have one of these two labels. The
Co-
braWare program allows other labels (see the CobraWare User’s Guide).