Lowrance NAC-2 Autopilot Computer User Manual
Model: NAC-2
1. Introduction
The Lowrance NAC-2 autopilot computer is a core component of a marine autopilot system, designed to provide reliable and precise vessel control. This low-current unit is specifically engineered for smaller vessels, supporting hydraulic and mechanical drives for boats up to 10 meters (33 feet) in length. It also features a solenoid output for compatible steering systems.
This manual provides essential information for the proper installation, operation, and maintenance of your NAC-2 autopilot computer, ensuring optimal performance and longevity.
2. Setup and Installation
Proper installation is crucial for the performance and safety of your autopilot system. It is highly recommended that installation be performed by a qualified marine electronics technician.
2.1 Mounting Location
- Mount the NAC-2 in a dry, protected location, away from direct sunlight, excessive heat, and moisture.
- Ensure adequate ventilation around the unit to prevent overheating.
- Mount securely using the provided hardware, ensuring the unit is stable and free from vibration.
2.2 Wiring and Connections
The NAC-2 features dedicated ports for power, drive, feedback, and network connections. Refer to the diagram below for port identification.
Figure 1: Lowrance NAC-2 Autopilot Computer showing the top view with "NAC-2 AUTOPILOT COMPUTER" label, and the side view with connection ports labeled "POWER", "DRIVE", "FEEDBACK", and "NETWORK". Mounting holes with screws are visible at the base.
- Power: Connect to a stable 12V DC power source, ensuring proper fusing and wire gauge for the expected current draw.
- Drive: Connects to the hydraulic pump or mechanical drive unit. Ensure correct polarity and secure connections.
- Feedback: Connects to the rudder feedback unit, which provides information on the rudder's position to the autopilot computer.
- Network: Connects to the NMEA 2000 network for communication with other marine electronics, such as chartplotters, displays, and sensors.
Always consult the detailed wiring diagrams provided in the full installation guide for your specific vessel and system configuration.
3. Operating the Autopilot System
The NAC-2 autopilot computer functions as the brain of your autopilot system, processing data from various sensors and controlling the steering mechanism. Operation is typically managed through a compatible autopilot controller or a multi-function display (MFD) connected via the NMEA 2000 network.
3.1 System Calibration
After installation, the autopilot system must be calibrated. This process typically involves:
- Compass Calibration: Swinging the vessel to allow the compass to learn its deviation.
- Rudder Calibration: Learning the full range of rudder movement.
- Dockside & Sea Trial Calibration: Fine-tuning performance parameters for optimal steering response in various sea conditions.
Refer to your autopilot controller or MFD manual for detailed calibration procedures.
3.2 Autopilot Modes
Common operating modes include:
- Auto Mode: Maintains a set course.
- No Drift Mode: Compensates for wind and current to maintain a ground track.
- Navigation Mode: Steers the vessel along a pre-programmed route from a chartplotter.
- Standby Mode: Disengages the autopilot, allowing manual steering.
4. Maintenance
The Lowrance NAC-2 autopilot computer is designed for durability and requires minimal routine maintenance. However, periodic checks can help ensure its long-term reliability.
- Visual Inspection: Periodically inspect the unit and its connections for any signs of corrosion, loose wires, or physical damage.
- Cleaning: Wipe the unit with a soft, damp cloth. Do not use harsh chemicals or abrasive cleaners. Ensure all ports are free of debris.
- Software Updates: Check the Lowrance website periodically for firmware updates for the NAC-2 and your connected devices. Keeping software up-to-date can improve performance and add new features.
- Connection Integrity: Ensure all network and power cables are securely fastened and free from strain.
5. Troubleshooting
This section provides basic troubleshooting steps for common issues. For more complex problems, contact Lowrance customer support or a certified marine electronics technician.
| Problem | Possible Cause | Solution |
|---|---|---|
| No Power to NAC-2 | Blown fuse, loose power connection, faulty power source. | Check fuse in the power circuit. Verify power cable connections at both the NAC-2 and the power source. Test the power source voltage. |
| Autopilot Not Engaging | System not calibrated, network issue, drive unit problem. | Ensure all system components (compass, rudder feedback) are connected and calibrated. Check NMEA 2000 network for proper communication. Inspect drive unit connections. |
| Erratic Steering | Poor calibration, interference, faulty sensor. | Recalibrate the autopilot system. Check for sources of magnetic interference near the compass. Inspect rudder feedback unit for smooth operation. |
| No Communication on Network | Loose network cable, missing terminator, network power issue. | Verify NMEA 2000 cable connections. Ensure network terminators are present at both ends of the backbone. Check NMEA 2000 network power. |
6. Specifications
| Feature | Detail |
|---|---|
| Brand | Lowrance |
| Model | NAC-2 |
| Item Weight | 4 Pounds |
| Color | Black |
| Material | Plastic |
| Operation Mode | Electric |
| Vessel Length (Max) | 10 meters (33 feet) |
| Drive Compatibility | Small hydraulic drives, mechanical drives |
| Output | Solenoid |
