Display Function - Marine Autopilots, Engine Controls and Instruments

Configure the output of your GPS, Plotter or PC
Activate NMEA-0183 output:
It is important to make the necessary settings
on your Nav equipment (GPS, Plotter or
PC), to activate the transmission of the route
data towards the Tecnautic autopilot and instruments.
Here are a few hints, for your consideration:
** The Tecnautic autopilot and displays use
magnetic bearings, not true bearings. It is
recommended to select also magnetic bearings
in the setup of your GPS or Plotter.
** Create and activate a route in your Nav
equipment. Verify that bearing "C", cross track
error ("r" or "L") and distance to the active
waypoint are displayed on your Autopilot Display.
At least bearing and cross track error are
required to permit the use of the autopilot NAV
mode.
** If your Nav equipment permits, activate
only the following output sentences: APB, RMC
and WDC. If this selection is not available, use
other sentences from the table on page 28 (lower
left), to receive the required data. For example
RMC can be substituted by VTG, APB can
be substituted by (BOD+XTE), BOD by
(RMB+RMC), WDC by BWC.
** Select a repetition rate of the sentence
output as high as possible on your Nav
equipment. This might be once per second,
depending on your equipment.
** The accuracy of the cross track error
data (XTE) of the Nav equipment can be selected
on some models. Select three (or
more) decimal digits, if possible.
The autopilot LAND mode must only be
used, when at least three decimal digits of
the cross track error are received. That has to
be verified on the AP-Display. The third decimal
remains always zero, if it has not been
received by the autopilot - do not use the
LAND mode in this case.
The autopilot NAV mode can be used with
only two decimal digits received. The resolution
of the cross track error is in this case only
0.010NM (18.5 meters).
** The way point switching law has to be
set up properly in your Nav equipment. It is
recommended to select (switching to the next
leg) "when abeam", or even "before abeam",
where "before" should be set to 5 seconds (or
0,005 NM to 0,010 NM).
Without verifying this setting, your Nav
equipment might switch too early to the next
way point, already far ahead of the active way
point.
** Curved tracks: If the Nav equipment
does not support curved tracks, you may split
a curved approach into a series of consecutive
short tracks. The difference to the next
track should not exceed 20 degrees, when
requiring accurate tracking in Land-Mode.
Contemporary Nav equipment:
All modern Nav equipment (GPS, Plotter,
PC) can provide the required basic sentences
for the autopilot.
NMEA Input at the SERVO-wheel:
From the following NMEA sentences, specific
data fields are read. The data are used
for displaying certain functions and for guidance
of the autopilot in NAV mode.
The NMEA input is not available at the remote
steering wheel.
APB: a) Cross Track Error
b) Mag+True bearing between way
points
BOD: Mag bearing between waypoints
BWC,BWR: Mag+True Brg and Dist of
pres.pos. to WP
GLL: Lat / Long
HDM, HDG:Magnetic Heading
MWV: Apparent Wind Angle and Speed
RMB: Cross Track Error,Bearing+Distance to WP
RMC: Ground Track, Speed and variation
VHW: a) Magnetic Heading
b) Water Speed (knots)
VTG: Mag Ground Track and Speed
VWR: Apparent Wind Angle and Speed
WDC: Distance to Waypoint
WDR: Distance to Waypoint
XTE: Cross Track Error (NM)
use RMB
data only
when also
receiving
RMC
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