NAC™ -2/NAC™ -3

Commissioning Manual
ENGLISH

www.bandg.com | www.simrad-yachting.com
Preface

Disclaimer
As Navico is continuously improving this product, we retain the
right to make changes to the product at any time which may not be
reflected in this version of the manual. Please contact your nearest
distributor if you require any further assistance.
It is the owner’s sole responsibility to install and use the equipment
in a manner that will not cause accidents, personal injury or
property damage. The user of this product is solely responsible for
observing maritime safety practices.
NAVICO HOLDING AS AND ITS SUBSIDIARIES, BRANCHES AND
AFFILIATES DISCLAIM ALL LIABILITY FOR ANY USE OF THIS PRODUCT
IN A WAY THAT MAY CAUSE ACCIDENTS, DAMAGE OR THAT MAY
VIOLATE THE LAW.
This manual represents the product as at the time of printing.
Navico Holding AS and its subsidiaries, branches and affiliates
reserve the right to make changes to specifications without notice.
Governing language
This statement, any instruction manuals, user guides and other
information relating to the product (Documentation) may be
translated to, or has been translated from, another language
(Translation). In the event of any conflict between any Translation of
the Documentation, the English language version of the
Documentation will be the official version of the Documentation.

Copyright
Copyright © 2020 Navico Holding AS.

Warranty
The warranty card is supplied as a separate document. In case of any
queries, refer to the brand website of your unit or system:
www.simrad-yachting.com
www.bandg.com

Preface | NAC-2/NAC-3 Commissioning Manual 3

 Compliance statements
Declarations
The relevant declarations of conformity are available at:
www.simrad-yachting.com
www.bandg.com

Europe
Navico declare under our sole responsibility that the product
conforms with the requirements of:
• CE under EMC Directive 2014/30/EU

United States of America

Warning: The user is cautioned that any changes or

modifications not expressly approved by the party
responsible for compliance could void the user’s
authority to operate the equipment.

Australia and New Zealand

Navico declare under our sole responsibility that the product
conforms with the requirements of:
• level 2 devices of the Radiocommunications (Electromagnetic
Compatibility) standard 2017

Trademarks
®Reg. U.S. Pat. & Tm. Off, and ™ common law marks. Visit
www.navico.com/intellectual-property to review the global
trademark rights and accreditations for Navico Holding AS and
other entities.
• Navico® is a registered trademark of Navico Holding AS.
• SIMRAD® is a registered trademark of Kongsberg Maritime AS,
Licensed to Navico Holding AS.
• B&G® is a registered trademark of Navico Holding AS.

4 Preface | NAC-2/NAC-3 Commissioning Manual

• AP™ is a common law trademark of Navico Holding AS.
• NAC™ is a common law trademark of Navico Holding AS.
• STEADYSTEER™ is a common law trademark of Navico
Holding AS.
• NMEA® and NMEA 2000® are registered trademarks of
the National Marine Electronics Association.

About this manual

Images used in this manual might not exactly match the screen on
your unit.

Important text conventions

Important text that requires special attention from the reader is
emphasized as follows:
Ú Note: Used to draw the reader’s attention to a comment or
some important information.

Warning: Used when it is necessary to warn

personnel that they should proceed carefully to
prevent risk of injury and/or damage to equipment/
personnel.

Translated manuals
Available translated versions of this manual can be found on the
following website:
• www.simrad-yachting.com
• www.bandg.com

Preface | NAC-2/NAC-3 Commissioning Manual 5

6 Preface | NAC-2/NAC-3 Commissioning Manual
 Contents
9 Introduction
9 NAC-2 and NAC-3 autopilot computers
9 Autopilot controllers
9 Autopilot computer setup

12 Dockside setup
12 Data source selection
12 Input function
13 Auto/Standby
13 Disengage
13 SteadySteer
14 Disable input
14 Boat characteristics
14 Drive configuration
17 Rudder setup

20 Sea trial
20 Compass setup
21 Transition speed
22 Set rudder zero position
22 Set turn rate
23 Tuning the autopilot

27 User settings
27 Steering profile settings
28 Sailing parameters
29 Turn pattern settings

33 Installation verification
33 Checklist
33 Boat specific settings

36 Maintenance
36 Preventive maintenance
36 Checking the connectors
36 Software update
36 Resetting the autopilot computer

Contents | NAC-2/NAC-3 Commissioning Manual 7

 38 Technical specifications
38 NAC-2
39 NAC-3

8 Contents | NAC-2/NAC-3 Commissioning Manual

1
Introduction

NAC-2 and NAC-3 autopilot computers

The NAC-2 and NAC-3 autopilot computers contain the electronics
needed to operate a hydraulic steering pump or mechanical drive
unit, while also interfacing with rudder feedback units and NMEA
2000 devices.
The NAC-2 is designed for boats up to 10 metres (33 feet) in length
and is suitable for low-current pumps, mechanical drive units, or
solenoid valves (8 A continuous/16 A peak).
The NAC-3 is designed for boats 10 metres (33 feet) or greater in
length and is rated to operate high-current pumps, mechanical
drive units, and solenoid valves (30 A continuous/50 A peak).

Autopilot controllers
The NAC can be controlled by various Simrad and B&G control units.
This can be dedicated autopilot controllers, Multifunction displays
(MFDs) and autopilot remote controllers used in combination with
instrument systems, or any combination of the above.

Autopilot functions
NAC-2 and NAC-3 include a large range of functions, but not all
autopilot controllers have access to all options. E.g. autopilot
systems including only an autopilot remote controller (without
display unit) do not have access to turn patterns.

The user interface

The autopilot functions are presented slightly different on the
different displays.
This manual shows screen examples from both MFDs and AP48.

Autopilot computer setup

When the autopilot installation is completed, the setup of the
autopilot computer must be performed. Failure in setting up the
autopilot correctly may prohibit the autopilot from functioning
properly.
The setup of the autopilot computer is divided in two main steps:

Introduction | NAC-2/NAC-3 Commissioning Manual 9

 • Installation settings
- Including dockside and seatrial commissioning. See "Dockside
setup" on page 12 and "Sea trial" on page 20
• User adjustment of autopilot settings
- Manual fine-tuning for various operational conditions and user
preferences. See "User settings" on page 27

Ú Note: Dockside settings can only be accessed when the

autopilot is in Standby mode.
Ú Note: Some systems require a dedicated physical standby key
to perform installation procedures. This key can be a key on the
autopilot controller, on an autopilot remote controller, or it can
be a separate standby key.

Warning: When the autopilot is delivered from

factory and any time after an autopilot reset has been
performed, the installation settings are all reset to
factory preset (default) values. A notification will be
displayed, and a complete setup has to be made.
Failure to do so correctly may prohibit the autopilot
from functioning properly!

10 Introduction | NAC-2/NAC-3 Commissioning Manual

Installation setup workflow

Introduction | NAC-2/NAC-3 Commissioning Manual 11

2
Dockside setup

Data source selection

Before commencing with autopilot computer setup the data
sources must be available and configured.
Data sources selection is required on initial start-up of the system, if
any part of the network has been changed or replaced, or if an
alternative source is made available for a given data type and this
source has not been selected automatically.
You can let the system automatically select your sources, or set up
each source manually. Refer to documentation for the autopilot
controller or for the display unit for details about how to perform
the data source selection.

Input function
Determines |how the autopilot computer/system reacts to an
external input. External input can be connected to blue/yellow wire
on NAC-2 and mode/function selector on NAC-3. For wiring details
and options, refer to the installation documentation.

Autopilot installation dialog, MFDs

12 Dockside setup | NAC-2/NAC-3 Commissioning Manual

 Autopilot installation dialog, AP48

Auto/Standby
Select this mode if you have a toggle button connected to your
NAC-2 autopilot computer. Press the button to toggle between
Auto and Standby mode.

Disengage
Select this mode if you have a disengage switch connected to your
NAC-3 autopilot computer.
• OPEN – Normal operation, can be controlled by controller.
• CLOSED to OPEN – Activates Auto mode regardless of previous
state.
• CLOSED – Disengaged. Cannot be controlled by controller.

SteadySteer
Select this mode if you have a SteadySteer connected to your
NAC-2/NAC-3.
• Manual steering overrides the active mode.
• If Auto mode or NoDrift mode was active before going into
manual steering, they will automatically re-engage when the
vessel has stabilized on a new course.
• For any other modes, the autopilot goes into Standby mode.
• If NAV mode was active before going into manual steering a
dialog will be shown.
- Confirm course change to reactivate NAV mode.
- Cancel the course change to activate Auto mode on the new
heading.
• If no action is taken the autopilot will go into Standby mode.

Dockside setup | NAC-2/NAC-3 Commissioning Manual 13

 Disable input
Select if no external input is connected or to disable connected
input.

Boat characteristics
Boat type
Affects steering parameters as well as available autopilot features.
The following options are available:
• Sail
• Displacement
• Planing
Ú Note: If the boat type is set to Sail, Virtual Rudder Feedback is
not available.

Boat length
Used by the autopilot system to calculate steering parameters.

Cruising speed
Used if no speed info is available. It is used by the autopilot system
to calculate steering parameters.

Drive configuration
The drive configuration controls how the autopilot computer
operates the steering system.
Refer to your drive unit documentation for relevant specifications.

Control method
Used for setting the appropriate control ouput for your drive.
The following options are available:
• Solenoid
For on/off steering of hydraulic valves. Gives fixed rudder speed.
• Reversible motor
For variable speed pumps/drives.

14 Dockside setup | NAC-2/NAC-3 Commissioning Manual

Drive voltage
Nominal drive voltage specified for your drive unit.
• Options: 12 V and 24 V.
Ú Note: 24 V output is only available with 24 V supply.
The setting must match the spec of the solenoids/pump/motor.

Warning: Selection of improper voltage level for your

drive unit may damage both the drive unit and the
autopilot computer even if the protection circuits are
activated.

Drive engage
Defines how the Engage output is used.
The following options are available:
• Clutch
If your drive unit/motor/pump needs clutch to engage the
actuator, it shall be connected to the "engage" output. Configure
the "Drive engage" as clutch. The clutch will be activated when
autopilot computer is controlling the rudder. In standby, the
clutch is released to allow manual steering. Check specification of
your drive unit to determine whether clutch is required.
• Auto
Output activated when autopilot computer is in Auto, NoDrift or
Navigation modes. For manual rudder control (Standby, NFU and
FU) the output is not activated. Typically used to switch between
two rudder speeds on a continuous running pump, used when
different rudder speeds are required for automatic and Follow-
up/Non-Follow-up steering.

Minimum rudder
Some boats may have a tendency to not respond to small rudder
commands around the “course keeping” position because of a small
rudder, whirls/disturbance of the water-stream passing the rudder,
or it is a single nozzle water jet boat. By increasing the Minimum
rudder parameter you may improve the course keeping

Dockside setup | NAC-2/NAC-3 Commissioning Manual 15

 performance on some boats. However, this will increase the rudder
activity.
Ú Note: Only set a value for minimum rudder if it proves to give a
better course keeping performance in calm sea. It should be set
after the autopilot steering parameters have been optimised/
tuned.

Rudder deadband
Prevents the rudder from hunting induced by mechanical play in
the steering gear or rudder.
The following options are available
• Auto
(Recommended).
The rudder deadband is adaptive and is continuously operative. It
will also optimize the deadband to the pressure on the rudder
• Manual
If the Auto setting doesn’t perform properly due to extreme
rudder speed and/or overshoot, it can be adjusted manually. Can
also be used to reduce the rudder activity. Rudder commands
smaller than the size of the dead band will be ignored
Find the lowest possible value that will prevent the rudder from
continuous hunting. A wide deadband will cause inaccurate
steering. It is recommended to check rudder stability in AUTO mode
at cruising speed to get pressure on the rudder. (Slight hunting
observed dockside may disappear at cruising speed.)

16 Dockside setup | NAC-2/NAC-3 Commissioning Manual

Rudder setup

Warning: During the rudder calibration and test the

autopilot computer issues a series of rudder
commands. Stand clear of the helm and do not
attempt to take manual control of the rudder during
this test!

Rudder source
The correct rudder source has to be selected before the rudder
feedback calibration can be performed.

Rudder source selection, MFDs

Dockside setup | NAC-2/NAC-3 Commissioning Manual 17

 Rudder source selection, AP48

Rudder feedback calibration

Ú Note: Only available if you have a rudder feedback unit installed
and selected as rudder source.
The rudder feedback calibration determines the rudder feedback's
direction.
• Follow the on-screen guided steps until the rudder calibration is
completed.

Rudder test
This rudder test verifies the drive direction. It detects minimum
power to drive the rudder and reduces the rudder speed if it
exceeds the maximum preferred speed for autopilot operation.
Ú Note: If the boat uses power assisted steering, it is important
that the engine or electric motor used to enable the power
assist steering is turned on prior to this test.
• Run the rudder test as described in the on-screen instructions
- Rudder should make a small movement within 10 seconds,
then follow up with travelling both directions
Failure to complete test will result in an alarm.

VRF calibration
Ú Note: Only available if the rudder source is set to a virtual
rudder feedback.

18 Dockside setup | NAC-2/NAC-3 Commissioning Manual

VRF calibration determines the direction of rudder movement, the
minimum output required to move the rudder and the voltage to
rudder speed ratio.
To perform the VRF calibration you must be able to view the
movement of the rudder.
• Follow the on-screen guided steps until the VRF calibration is
completed.
Ú Note: When you get asked if the rudder moved you may have
to select no several times to ensure the pump provides enough
power to turn the motor at high vessel speed.

Dockside setup | NAC-2/NAC-3 Commissioning Manual 19

3
Sea trial
A seatrial can only be performed after the dockside settings are
completed.
Ú Note: The seatrial must always be performed in calm
conditions, in open waters and at a safe distance from other
traffic.

Compass setup
To achieve the best possible performance, the compass should be
calibrated, and any offsets should be compensated for.
The setup needs to be done from an appropriate display unit.
Depending on the unit, access to the compass setup is available
from the compass’s device dialog, or from a dedicated Calibration
option in the unit’s Settings menu.

Device dialog, MFDs

20 Sea trial | NAC-2/NAC-3 Commissioning Manual

 Calibration option, AP48

Ú Note: The setup of the compass should be done in calm sea

conditions and with minimal wind and current to obtain good
results. Ensure that there is enough open water around the
vessel to make a full turn.
Refer to your heading sensor's documentation for further details for
your unit.

Transition speed
Ú Note: Only available if the boat type is set to Planing.
The transition speed is the speed at which the system automatically
changes between Low speed and High speed profiles.
The profiles are used to accommodate the boats' tendency to
exhibit different steering characteristics at different speeds. You may
also have different preferences about the steering performance of
your boat required at low and high speeds.
It is recommended that you set a value that represents the speed
where the boat's steering characteristics change. For instance the
planing threshold (recommended), or at the speed you want the
autopilot to change behavior.
There is a 2 knots hysteresis to prevent oscillation of high/low
settings when the vessel is travelling at or near the transition speed.
Example
The transition speed is set to 9 knots.
• The system changes from Low profile to High profile when the
speed increases to 10 knots (= Transition speed plus 1 knot)

Sea trial | NAC-2/NAC-3 Commissioning Manual 21

 • The system changes from High profile to Low profile when the
speed decreases to 8 knots (= Transition speed minus 1 knot)
The active profile ('Low' or 'High') is shown in the autopilot page
(e.g. AP44) and in the autopilot pop-up (MFDs):

AP48 page MFD Autopilot control bar

Set rudder zero position

Used to correct the rudder zero position found during dockside
commissioning if the boat needs a small rudder offset in order to
steer straight.
Ú Note: Setting rudder zero position should always be done in
calm conditions, where steering is not affected by wind and/or
current.
Bring the rudder to the position where the boat steers straight, then
activate the Set rudder zero option to save the rudder zero
parameter.
Ú Note: On dual engine boats, verify that the engine RPM is equal
on both engines so that the thrust from both propellers is
equal. Otherwise, the zero rudder position might be set wrong.

Set turn rate

Used for setting the preferred turn rate of the boat.
Bring the boat into a turn with the preferred safe and comfortable
turn rate, then activate the Set turn rate option to save the turn
rate parameters.
Ú Note: The captured turn rate will be stored in the active
steering profile. This setting must therefore be repeated for
each steering profile.

22 Sea trial | NAC-2/NAC-3 Commissioning Manual

Tuning the autopilot
Ú Note: Tuning of the autopilot must be done separately for low
and high speed profiles.
Both Autotune and manual tuning should be performed in
calm or moderate sea conditions.
Providing you have entered correct vessel type, length and cruising
speed, you may not have to perform further manual or automatic
tuning.
Proceed as follows to verify satisfactorily steering:
1. Stabilize the vessel on a heading, and then select AUTO mode
2. Observe course keeping and rudder commands
- The autopilot should keep the vessel on the set heading
within an average of +/-1 degree, providing calm sea and
wind
3. Make some small and bigger heading changes to port and
starboard and observe how the vessel settles on the new
heading
- The vessel should have a minimum of overshoot. See "Rudder
gain" on page 25 and "Counter rudder" on page 25.
If the autopilot is not keeping the heading satisfactorily or not
making the turns satisfactorily, you may now either try the Autotune
function or go directly to manual tuning.
Ú Note: If the vessel is more than approximately 30 m/100 ft or
has a very high cruising speed it may be unpractical to perform
Autotune. It is then suggested to proceed with manual tuning.

Autotuning
When performing an autotune, the vessel will automatically be
taken through a number of S-turns. Based on the vessel behavior,
the autopilot will automatically set the most important steering
parameters (Rudder gain and Counter rudder).
• Stabilize the vessel on a heading and set the speed between 5-10
kn, then select Autotune.
- The autopilot will now switch to AUTO mode and take control
of the vessel.
Ú Note: Autotuning can be stopped at any time by pressing the
STBY key on the autopilot controller.

Sea trial | NAC-2/NAC-3 Commissioning Manual 23

 The autotuning takes approximately 3 minutes to complete. When
completed the autopilot automatically switches to Standby mode,
and the rudder must be controlled manually.
Ú Note: All parameters that are set during autotuning can be
manually adjusted. For optimal steering performance it is
recommended to manually adjust the steering parameters after
running the autotune.

Manual tuning
Rudder gain and Counter rudder can be manually adjusted.
• Stabilize the vessel on a heading and set the speed in the middle
of the profile range (well clear of the transition speed) to avoid
profile switching during tuning. Then activate the Rudder gain
option. Adjust the value according to the descriptions below.
• If required, adjust slightly the Counter rudder option.

Tuning parameters, MFDs

24 Sea trial | NAC-2/NAC-3 Commissioning Manual

 Tuning parameters, AP48

Rudder gain
This parameter determines the ratio between commanded rudder
and the heading error. The higher rudder gain value the more
rudder is applied. If the value is too small it will take a long time to
compensate for a heading error, and the autopilot will fail to keep a
steady course. If the value is set too high the overshoot will increase
and the steering will be unstable.

A The value is set too high. Steering becomes unstable and

often the overshoot will increase
B The value is set too low. It will take a long time to
compensate for a heading error, and the autopilot will fail to
keep a steady course

Counter rudder
Counter rudder is the amount of counteracting (opposite) rudder
applied to stop the turn at the end of a major course change. The
settings depend on vessel’s characteristics, inertia, hull shape and
rudder efficiency.

Sea trial | NAC-2/NAC-3 Commissioning Manual 25

 • If the vessel has good dynamic stability, a relatively small value
will be sufficient
• An unstable vessel will require high value
• The greater the vessel’s inertia, the greater value will be required
Increasing counter rudder value may result in some higher rudder
activity also when steering a straight course, particularly in high
waves.
The best way of checking the value of the Counter rudder setting is
when making turns. The figures illustrate the effects of various
Counter Rudder settings.

A B C

A Counter rudder value too low; overshoot response

B Counter rudder value is too high; sluggish and creeping
response
C Correct setting of Counter rudder; ideal response

Perform various course changes and observe how the boat settles
on the new heading. Start with small changes, 10-20 degrees, and
proceed with bigger changes, 60-90 degrees. Adjust Counter rudder
value to obtain best possible response as in illustration C.
Ú Note: As many boats turns differently to port versus starboard
(due to propeller rotation direction), do the course changes in
both directions. You may end up with a compromise setting of
Counter rudder that gives a little overshoot to one side and a
bit creeping response to the other.

26 Sea trial | NAC-2/NAC-3 Commissioning Manual

4
User settings
The user settings can be configured differently between the
different profiles, depending on boat steering characteristics and
user preferences.

Steering profile settings

The NAC include two steering profiles (High and Low), used for high
and low boat speed.
The initial parameters are automatically assigned when you select
your vessel type. During the seatrial the parameters will be tuned for
optimized steering performance. See "Tuning the autopilot" on page 23.
The options listed in the next pages are available for both High and
Low speed profiles.
For Rudder gain and Counter rudder, see "Rudder gain" on page 25 and
"Counter rudder" on page 25.

Turn rate
Used for manually setting the turn rate used when the heading
change is larger than 5°.

Autotrim
Controls how fast the autopilot will apply rudder to compensate for
a constant heading offset, e.g. when external forces such as wind or
current affects the heading. Lower autotrim will give faster
elimination of a constant heading offset

Init rudder
Defines how the system moves the rudder when switching from
hand steering (Standby, FU and NFU) to an automatic mode.
The following options are available:
• Center
Moves the rudder to zero position
• Actual
Maintains the rudder angle, and assumes that the current rudder
angle is the trim required to maintain a steady heading.

User settings | NAC-2/NAC-3 Commissioning Manual 27

 Rudder limit
Determines the dynamic range of the rudder before its movement
is restricted and alarm is triggered. Typical usage is to limit the
amount of rudder action caused by yawing in following sea.
Ú Note: Rudder limit is not a hard limitation of the rudder range,
only around the current setpoint.
This Rudder limit does not affect Non-Follow-up or Follow Up
steering.

Off heading limit angle

Sets the limit for the off heading alarm.
When the alarm option is activated an alarm occurs when the actual
heading deviates from the set heading more than the selected limit.

Track response
Defines how aggressively the autopilot should steer towards the
active route's leg.

Track approach angle

This setting is a limit to prevent approaching the track too steeply.
Approaching the track at shallower angles is permitted depending
on the cross track distance (XTD) and track response setting.
This setting is used both when you start navigating and whenever
the autopilot is working the boat towards the route.

Course change confirm angle

Defines the limit for automatic course change to next waypoint in a
route when the autopilot is following a route (NAV mode).
If the course change is greater than this set limit, you are prompted
to verify that the upcoming course change is acceptable.

Sailing parameters
Ú Note: Only available if the boat type is set to SAIL.

Wind mode
Select what wind angle the autopilot will steer towards.

28 User settings | NAC-2/NAC-3 Commissioning Manual

The following options are available:
• Auto
If True Wind Angle (TWA) is <70º: Wind mode will steer towards
Apparant Wind Angle (AWA)
If TWA is ≥70º: Wind mode will steer towards TWA
• Apparent
Steers towards AWA
• True
Steers towards TWA

Tack time
Controls how fast the autopilot tacks in wind mode.

Tack angle
Controls the angle that the boat will tack to in AUTO mode.

Manual speed
If neither boat speed nor SOG data are available and/or deemed
unreliable, a manual value for speed can be entered and used by
the autopilot to aid steering calculations.

Turn pattern settings

The autopilot computer supports a number of automatic turn
steering features when the autopilot is in AUTO mode.
Ú Note: Turn pattern steering is not available if the boat type is
set to Sail.
All turn patters, except the U-turn, have associated turn pattern
settings. Depending on the autopilot controller these turn pattern
settings can be adjusted before you start the turn or during the turn.

User settings | NAC-2/NAC-3 Commissioning Manual 29

 Turn pattern settings, MFD

Turn pattern settings, AP48

Ú Note: Not all autopilot controllers include turn pattern steering.

Refer to your autopilot controller for more information.

C-turn (Continuous turn)

Steers the vessel in a circle.
• Turn variable:
- Rate of turn. Increasing the value makes the vessel turn a
smaller circle.

30 User settings | NAC-2/NAC-3 Commissioning Manual

U-turn
Changes the current set heading to be 180° in the opposite
direction.

Spiral turn
Makes the vessel turn in a spiral with a decreasing or increasing
radius.
• Turn variables:
- Initial radius
- Change/turn. If this value is set to zero, the boat will turn in a
circle. Negative values indicate decreasing radius while positive
values indicate increasing radius.

Zigzag turn
Steers the vessel in a zigzag pattern.
• Turn variables:
- Course change (A)
- Leg distance (B)

B A

Square turn
Makes the vessel automatically turn 90° after having travelled a
defined leg distance.
• Turn variable:
- Leg distance

S-turn
Makes the vessel yaw around the main heading.
• Turn variables:
- Course change (C)
- Turn radius (D)

User settings | NAC-2/NAC-3 Commissioning Manual 31

 C D

Depth contour tracking (DCT)

Makes the autopilot follow a depth contour.
Ú Note: DCT turn pattern is only available if the system has a valid
depth input.

Warning: Do not use the DCT turn pattern unless the

seabed is suitable. Do not use it in rocky waters where
the depth is varying significantly over a small area.

• Turn variables:
- Depth gain. This parameter determines the ratio between
commanded rudder and the deviation from the selected depth
contour. The higher depth gain value the more rudder is
applied. If the value is too small it will take a long time to
compensate for drifting off the set depth contour, and the
autopilot will fail to keep the boat on the selected depth. If the
value is set too high the overshoot will increase and the
steering will be unstable.
- CCA. The CCA is an angle that is added to or subtracted from
the set course. With this parameter you can make the boat yaw
around the reference depth with s movements. The larger the
CCA the bigger yawing will be allowed. If the CCA is set to zero
there is no S-ing.
- Ref. depth. This is the reference depth for the DCT function.
When DCT is initiated the autopilot reads the current depth
and set this as the reference depth. The reference depth can be
changed when the function is running.
Ú Note: If depth data is lost during DCT the autopilot will
automatically switch to AUTO mode.
It is recommended to turn ON the AP Depth Data Missing alarm
when using DCT. When this alarm is activated an alarm will be
raised if the depth data is lost during DCT.

32 User settings | NAC-2/NAC-3 Commissioning Manual

5
Installation verification
When all units in the autopilot system are installed, external
equipment connected and the software configured according to
the previous chapters, the installation should be verified according
to the checklist. The boat specific settings should be noted down in
the relevant tables included this chapter.

Checklist

Description Reference
Units mounted and secured Installation instructions for the
according to instructions units
Network powered and
terminated according to Wiring instructions for the units
instructions
Autopilot control unit
Sources selected
documentation
Vessel configured "Boat characteristics" on page 14
Drive units configured and
"Drive configuration" on page 14
calibrated
Compass calibrated "Compass setup" on page 20
Seatrial completed (manual or
"Sea trial" on page 20
autotune)

Boat specific settings

Boat

Settings
Boat type
Boat length
Cruising speed
Transition sped

Installation verification | NAC-2/NAC-3 Commissioning Manual 33

 Drives

Settings
Drive type
Drive control method
Nominal drive voltage
Drive engage
Minimum rudder
Rudder deadband
Manual deadband
Minimum output
Maximum output

Sailing parameters

Settings
Wind mode
Tack time
Tack angle
Manual speed

Steering profiles

Settings Low Speed High Speed

Turn Rate
Rudder gain
Counter rudder
Autotrim
Init rudder
Rudder limit

34 Installation verification | NAC-2/NAC-3 Commissioning

Manual
 Settings Low Speed High Speed
Off heading limit
Track response
Track approach
angle
Course change
confirm angle

Turn Pattern settings

Settings
Continuous
Rate of turn
Spiral
Initial radius
Change/turn
Zigzag
Course change
Leg distance
Square
Leg distance
Lazy-S
Course change
Turn radius
Depth contour
Depth gain
CCA

Installation verification | NAC-2/NAC-3 Commissioning Manual 35

6
Maintenance

Preventive maintenance
The unit does not contain any field serviceable components.
Therefore, the operator is required to perform only a very limited
amount of preventative maintenance.

Checking the connectors

The connectors should be checked by visual inspection only.
Push the connector plugs into the connector. If the connector plugs
are equipped with a lock, ensure that it is in the correct position.

Software update
You can update the software for the autopilot computer from a
display unit connected to the network.
You can check the autopilot computer's software version from the
display unit's Device list.
The latest software is available for download from the product
website on www.simrad-yachting.com and www.bandg.com.

Resetting the autopilot computer

You can reset the autopilot to factory default settings.

Reset autopilot computer, MFDs

36 Maintenance | NAC-2/NAC-3 Commissioning Manual

 Reset autopilot computer, AP48

The first time the autopilot computer is started after reset, it will run
through the automatic setup-procedure.
Ú Note: Unless you need to clear all values set during the
installation set-up procedure, you should not perform a reset of
the autopilot computer.

Maintenance | NAC-2/NAC-3 Commissioning Manual 37

7
Technical specifications
Ú Note: The most up-to-date specifications list is available at:
www.simrad-yachting.com

NAC-2

Approvals
Compliance EMC directive 2014/30/EU
Electrical
Supply voltage 9-31.2 V DC
Power consumption - Max 500 W
Power consumption - Typical As required to drive rudder
actuator. See pump/motor
power ratings
Recommended fuse rating 20 A
Environmental
Operating temperature -25°C to +55°C (-13°F to 131°F)
Storage temperature -30°C to +70°C (-22°F to 158°F)
Waterproof rating IPx5
Humidity 100%
Shock and vibration Acc to EN60945
Connectivity
NMEA 2000 1 Micro-C port, 1 LEN
Drive 12/24 V DC, min 10 mA, max 3 A
Rudder Feedback Variable voltage/resistive 0‐5 V
Physical
Weight 0.6 kg (1.3 lbs)
Compass Safe Distance 500 mm (20 inches)
Warranty 2 years

38 Technical specifications | NAC-2/NAC-3 Commissioning

Manual
NAC-3

Approvals
Compliance EMC directive 2014/30/EU
Electrical
Supply voltage 12/24 V DC +/- 10-30%
Power consumption - Max 750 W
Power consumption - Typical As required to drive rudder
actuator. See pump/motor
power ratings
Recommended fuse rating 30 A
Environmental
Operating temperature -25°C - +55°C (-13°F - 131°F)
Storage temperature -30° - +70°C (-22°F - 158°F)
Waterproof rating IPx5
Humidity 100%
Shock and vibration Acc to EN60945
Connectivity
NMEA 2000 1 Micro-C port, 1 LEN
NMEA 0183 1 port IN/OUT. 4.8, 9.6,
19.2 & 38.4 kbaud
Drive • Reversible motor control
of rudder.
Max continuous load 30
A, peak 50 A for 1s
or
• On/off
solenoid control of rudder.
12/24 V DC,
common, load range 10
mA to 10 A, off current <1 mA

Engage Output for bypass/clutch. 12/24

V DC, min 10 mA, max 3 A

Technical specifications | NAC-2/NAC-3 Commissioning Manual 39

 Rudder Rudder angle, frequency input.
15 V, 1.4 to 5 kHz, resol. 20 Hz/°
Remote • Input: External open/
close contact for remote
controller
• Output: High/Low mode
indicator signal

Mode External open/close

or pulse contact for autopilot
disengage
Alarm External alarm output for
buzzer/relay. Max 100 mA,
voltage level as local supply
Physical
Weight 0.7 kg (1.6 lbs)
Compass Safe Distance 500 mm (20 inches)
Warranty 2 years

40 Technical specifications | NAC-2/NAC-3 Commissioning

Manual
*988-11233-003*