Navitron NT921 MK2



Overview
Specifically designed for small professional vessel use (typically 11-20m LOA) the NT921 MKII Autopilot provides a powerful combination of steering system control and interface facilities based on an extremely intelligent Control Unit which is clearly marked and simple to operate.

Accordingly, the NT921 MKII offers Navitron steering expertise in a robust and compact package which includes the following special features: –

  • Dual Channel Heading Inputs: – NMEA 0183 Direct and Mag Sensor Coil
  • Built in Radio Navigator Interface for selectable (HI and LO) automatic track steering between waypoints.
  • Fully automatic stability compensation for variations in rudder speed.
  • Three Heading output Channels for Radar Stabilisation etc. (NMEA, Furuno & Step by Step)

Straightforward operation is a key feature of the NT921 MKII thus operator controls are kept to a minimum and are clearly identified by control panel markings which are red backlit for night viewing via a variable intensity illumination control.

A conventionally marked Course Selector permits simple course selection which is automatically corrected to maintain the vessel on a specified track when connected to a GPS or Track Plotter programmed with a track based on predetermined waypoints.

In addition to Track data, the NT921 MKII will also accept NMEA heading data directly from GPS compass systems etc. When dual heading inputs are employed (NMEA + mag sensor coil) the priority source is installation programmable with automatic changeover in the event of primary source failure.

Suitable for console or bracket mounting, the NT921 MKII Control Unit is intended for wheelhouse location and is supplied complete with Heading Sensor Coil and Rudder Reference Unit for installation to solenoid hydraulic systems (11-40Vdc/5A max).

High voltage solenoids (110/220Vac/dc) can also be accommodated via the inclusion of an optional Universal Relay Box type NT920URB.

Alternatively analogue signal control of water jets or analogue steering machines requiring -10v/+10v inputs can be configured via the inclusion of a Navitron Analogue Steering Interface (NT990ASI).

A microprocessor based Autopilot for magnetically and GPS compass / track steered vessels from typically 10 – 20m (30 – 65ft).

Typical Applications: –

  • Workboats
  • Fishing Vessels
  • Survey Units
  • Patrol Craft

Standard Features: –
Full P.I.D Intelligence,
Servo driven Heading Repeater (Standby mode),
Dual Course Setting and Steer on Lock on facility,
Full Automatic Permanent Helm,
Digital displays of Heading, Rudder Angle and Cross Track Error (CTE),
Operator variable control panel illumination,
11-40Vdc Power Supply compatibility,
Solid State Output stages. (11-40Vdc/5A max),
Full range menu driven installation presets.

Optional Equipment: –
Rudder Indicators,
Power Steer Controls,
Off Course Alarm,
Watch Alarm,
Universal Relay Box,
Analogue Steering Interface,
Dual Steering Interface,
Bowthruster Interface.

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Technical Specification

Supply
Voltage
11-40Vdc
Panel
Displays: –
Rudder
Angle
2
Digit + LCD Bar
Power
Consumption
12v
24v
Heading
Indicator
Servo
Card in

Standby Mode and

3 Digit LCD Display

Standby
3.0W
3.6W
On
3.3W
3.9W
Illumination
(max)
5.8W
7.0W
CTE Indicator
LED
Autopilot
Mode
LED
Indication of

Standby, Auto &

Remote

Solenoid
Switch Ratings: –
Voltage
11-40Vdc
RadioNav
Mode
LED
Indication of CTE &

Auto Heading Correct

Current
5A
(max)
Switchline
Polarity
Installation

Selectable

CTE

Correction Angle

3
Digit LCD Display

2 Digit LCD Display

Switch
Type
Solid
State
(via
auto Heading display updates at 15 second intervals)
Operator
Controls: –
Yaw
Panel
Alarms: –
Rudder
Remote
Engaged
LED
+ Audible
Autopilot
Mode Switch
Data Input Fail
(CTE)
LED
+ Audible
RadioNav
Mode Switch
Max Correction
LED
+ Audible
Illumination
Red
Backlight
Heading
Input Sentences from GPS

Compass etc: –

Mechanical
Width
259mm
NMEA
0183
XX
HDT, XX HDG

XX HDM, XX HCC

Height
176mm
Depth
– behind bezel
115mm
Weight
3.9Kg
XTE / HTS
Input Data (from GPS/Plotter)
NMEA
0180
NMEA
0183

XX HSC (Priority)
XX APA, XX APB

XX RMB, XX XTE

Heading
Output to Radars / Track Plotters etc.
Step
by Step
Selectable
3, 6, 12 or 24 steps per degree
1Hz
11Hz
22Hz
NMEA
0183

Sentence types

@ 1, 11 & 22Hz

APHDG, APHCC
HCHDG, HCHCC

or HEHDT, AGHDT

HCHDG,
HCHDM

or

HEHDT, AGHDT

HCHDM

or

HEHDT

Furuno
Format
Selectable
0.1° or 0.166° resolution
Selectable
5Vpp or 11Vpp output
Selectable
5Hz or 40Hz update rate

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