How do you use the ComNav Avenger autopilot?
I've recently bought a used sports cruiser fitted with a ComNav Avenger autopilot at the helm. I don't have the original manual, and the button layout isn't entirely intuitive to me. How do I actually engage it, adjust my heading on the fly, and use the basic features without sending the boat into a sudden, aggressive turn?
Answer
To use the ComNav Avenger autopilot, manually steer your boat onto the desired heading, let the compass settle, and press the 'AUTO' button to lock the course. You can then make minor directional tweaks using the port and starboard arrow keys, or press 'STANDBY' at any time to instantly return manual control to the helm.
Engaging and Adjusting Course
Power up the Avenger via the main 12V or 24V breaker panel and it defaults to STANDBY mode. The LCD screen displays the current magnetic heading from the fluxgate compass. The autopilot monitors the heading but leaves the steering to you.
Hand control over to the autopilot by following these steps:
- Steer the boat manually in a straight line at normal cruising speed.
- Wait a few seconds for the boat to settle on the heading. Do not engage the autopilot halfway through a turn.
- Press the AUTO button. The mechanical clutch engages or the hydraulic pump valves close, and the autopilot takes the wheel.
- Adjust the course using the port (red) and starboard (green) arrow buttons. A quick press alters the heading by 1 degree. Holding the button down initiates a larger continuous course change.
Warn the crew before initiating a turn greater than 10 degrees at cruising speed to prevent anyone losing their footing.
Navigating in NAV Mode
The Avenger steers to a specific waypoint or follows a pre-programmed route when networked to a GPS chartplotter via an NMEA 0183 connection. This mode suits longer passages where you must account for cross-track error caused by wind and tide.
- Activate a 'Go To' waypoint or route on your chartplotter.
- Steer the boat manually so the bow points roughly towards the target waypoint.
- Press the NAV button on the control head. The screen indicates it is receiving navigation data.
The autopilot reads the Cross Track Error (XTE) from the plotter and adjusts the rudder to keep you strictly on the rhumb line. When you reach a waypoint and the plotter calls for a major course change, the Avenger sounds an alarm. It waits for you to acknowledge the turn by pressing the NAV or AUTO button, ensuring the boat never veers off without permission.
Fine-Tuning Gain and Seastate
A poorly tuned autopilot snakes aggressively through the water or reacts too sluggishly to waves. The Avenger allows you to adjust the rudder gain (how much rudder is applied for a given course error) and the seastate (yaw tolerance).