Navitron NT921G



Overview
Purpose designed by Navitron Systems Limited for professional use on Magnetic and/or Gyro based commercial vessels of all types to approximately 2000 gross registered tonnes, the Navitron NT921G is a powerfully equipped and technologically advanced Autopilot which is R.M.R.S and Morsviasputnik Type Approved to IMO and ISO specifications.

  • Dual Mag Inputs: – Sensor Coil and/or NMEA.
  • Dual Gyro Inputs: – 1:1 Synchro and/or NMEA.
  • Built in RadioNav: – Track steer via GPS / Plotter.
  • Off Course Alarm: –
  • Automatic Stability : – Monitors Rudder speed.
  • 3 x Heading Outputs: – NMEA, Step by Step and Furuno formats.

Fully programmable to provide optimum installation flexibility and final seagoing performance, the NT921G Autopilot is also simple to operate via a clearly defined ‘push and rotate’ Heading selector supplemented by +1°/-1° keys for fine course adjustment use when appropriate.

Track steering based on Cross Track Error (XTE) data received from the ships GPS system is also a standard feature providing automatically corrected direction over the ground between predetermined waypoints.

The control unit is suitable for console or bracket mounting in bridge or wheelhouse locations. Standard system supply also comprises a Mag Heading Sensor Coil and Rudder Reference Unit for installation to low voltage solenoid operated (11-40Vdc max) hydraulic steering systems.

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

A second Mag input facility is provided to accept NMEA heading data from a proprietary source and dual Gyro input ports are standard to accept NMEA and/or 1:1 isolated Synchro heading data.

Where Step by Step, M-type or non 1:1 Synchro ratios are involved, a Fully Type Approved Gyro interface (type NT925HDI) is available. Similarly, fully Type Approved Analogue and Dual Steering Interfaces are available for Azimuth propulsion units and Dual rudder systems respectively.

A Type Approved installation programmable Autopilot for Mag and/or Gyro based vessels from 18m to approximately 2000 gross registered tonnes.

Typical Applications: –

  • Deep water Fishing Vessels and Workboats
  • Coasters, Dredgers, Survey and Support Units
  • Tugs
  • Ferries
  • Military 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 (Automatic Trim),
Heading, Rudder angle and Track data displays,
Programmable Rate of Turn,
Automatic Rudder stabilisation compatible with
dual speed steering systems,
Operator variable control panel illumination,
11-40Vdc Power Supply compatibility,
Solid State Output stages (11-40Vdc / 5A Max).

Optional Equipment : –
Rudder Indicators,
Power Steer Controls,
Digital and Analogue Heading Repeater,
Watch Alarm,
Universal Relay Box,
Analogue Steering Interface,
Dual Steering Interface,
Bow Thruster Interface.

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Technical Specification

Whilst the NT921G and NT990G autopilots are similar in appearance and apparently identical in terms of the parameters specified below, it should be noted that the software structures differ significantly to reflect the steering and response characteristics of vessels up to approximately 2000 grt (NT921G) compared with larger vessels from approximately 2000 grt upwards (NT990G).

Certification
Standards: –
Russian Martime Register of Shipping
(R.M.R.S) and
Morsviasputnik Type Approved in accordance with ISO 11674 & IMO A342 (IX) as amended by MSC64/67
Annex 3.

Autopilot
Input / Output Specifications

Inputs:
Outputs:
Supply
Voltage Range
11-40Vdc
NMEA
0183 Heading Data (Isolated RS422)
Power
Consumption
2.5W
(@24Vdc)
Update
Rate
Selectable
@
1Hz, 11Hz or 22Hz
Illumination
Max
8.1W
(@24Vdc)
&nbspSentence
Types (Mag/Gyro
versus
Update Rate)
Hz
Mag
Gyro
Mag
Heading Input Ports: –
1
HCHCC
&nbsp
Navitron
Heading Sensor Coil mounted above or below existing Mag compass
Coil
type

HSC1 or HSC2

HCHDG
HEHDT
APHCC
AGHDT
APHDG
&nbsp
11
HCHDM
HEHDT
Resolution
0.25°
HCHDG
AGHDT
22
HCHDM
HEHDT
NMEA
0183 Heading Sentence from Electronic Compass (Priority and max update
rate as shown)
XX
HDM
25Hz
Resolution
0.1°
XX
HDG
16Hz
XX
HCC
28Hz
Furuno
Heading Format: –
XX
HDT
25Hz
Update
Rate
Selectable
@

5Hz or 40Hz

Resolution
0.1°
Resolution
Selectable
@
0.166° or 0.1°
Gyro
Heading Input Ports: –
Isolated
1:1 Synchro
(if available in Gyro)
400Hz
Excitation

from Autopilot

Signal
Amplitude
Selectable
@
5Vdc or 12Vdc
Resolution
0.25°
Step by
Step Heading Data: –
NMEA
0183 Heading Sentence from Gyro or optional NT925HDI (Priority and max
update rate as shown)
XX
HDT
25Hz
Steps
per degree
Selectable
@
3, 6, 12 or 24
XX
HDM
25Hz
XX
HDG
16Hz
Signal
Amplitude
5Vdc
XX
HCC
28Hz
Resolution
0.1°
Navitron
Custom Serial Heading Data: –
(to
Navitron Digital Repeaters)
Follow
Up Rate (Minimum): –
All
Heading Input Types
30°
/ Sec
Navitron
Serial Input/Output Data: –
(to
/ from Navitron Bowtruster Interface
and Analogue Steering Interface options)

Cross
Track Error Signal Input

(from GPS/Plotter etc. for Track mode use)

NMEA
0183
Sentence types
XX
APA
Solid
State Solenoid Switching: –
XXAPB
Polarity
Selectable
@
Common +VE/-VE
XXRMB
XX
XTE
Max
Rating
5A
(11-40Vdc)
NMEA
0180
(CTE
Only)
Panel
Alarms: –
Operating
Temp Range
-20
to +60 °C
Power
Fail
(int
/ ext supply fail)
Steering
Fail
(no
rudder response)
Operator
Control & Selectors: –
Heading
Input
(no
heading data)
Yaw
  Alarm
Test/Cancel
Data
Input Fail
(no
Track data)
Rudder Autotrim
On/Off
Off
Course

(specified limit exceeded)
Counter
Rudder
Track
On/Off
Rudder
Limit
(spec’d
limit/ROT reached)
Rudder
Limit
Track
HI/LO Resolution
Remote
(remote
station engaged)
Illumination Off
Course Alarm level
Alarm
Test
(tests
all alarms)
Mode
Switch
+1°
/ -1° keys (NT921G)
Gyro/Mag
Selector
Cancel/Confirm
keys

(NT990G)

Mechanical
NT921G/990G Control Unit
Width
297mm
Height
176mm
Compass
Safe Distance: –
Depth
– behind

bezel

110mm
NT921G/990G
Control Unit
0.6m
Weight
3.3Kg

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Dimensions

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