ComNav Commander P2 & P2VS Installation & Operation Basic Operations
Document PN 29010074 V4.1 - 139 -
Off
(silent sequencing):
•
Automatically turn the boat to the next waypoint in a route.
Caution! In “Off”, no waypoint arrival alarm will be displayed.
Typically, you would choose this option if your Navigation System has its own
waypoint arrival alarm that cannot be turned off, and you do not wish to
acknowledge the same alarm on multiple devices.
Correction
This parameter selects which of the three methods the autopilot will use to update the
Commanded Heading when in
NAV
mode:
•
“CTS” – Course To Steer
•
“XTE” – Cross-Track Error
•
“Both”
See
Understanding NAV Mode
, above for full details.
XTE Sense (Cross-Track Error Sense)
Cross Track Error (XTE) contains two pieces of information. First, it contains the
amount
of
the error. Secondly, it gives information about the ‘sense’ of the error – that is, whether the
boat is to the
left
or the
right
of the line between the beginning and ending waypoints.
The NMEA 0183 Standard specifies how the Cross-Track Error should be identified. An `L´
indicator in the data sentence means the boat should steer to the left, and an `R´ indicator
meaning the opposite.
However, some manufacturers of GPS, chartplotters, and other Navigation devices &
systems have taken the `L´ indicator to mean that the boat is to the left of the line, so the boat
should steer to the right, and the `R´ indicator to mean the opposite.
Because of this confusion, the P Series autopilot’s handling of XTE can be switched from
“Norm” (normal) to “Rev” (reverse).
•
In “Norm”, the autopilot will respond normally (i.e., in the way defined in the NMEA
Standard) to the sense of the Cross-Track Error.
•
In “Rev”, the autopilot will respond in the opposite way in response to the same
information.
Max Correction
When activating pre-stored routes when there will be a large amount of initial Cross-Track
Error, the autopilot will steer the boat at almost 90° to the Track to the first waypoint, in order
to get back on-track as fast as possible.
In certain circumstances, this can appear as though the boat is actually moving away from
the waypoint.
You can minimize this phenomenon by setting Max Correction to something less than 90°.
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