Overview

The Raymarine M81105 is a rotary rudder reference transducer for compatible Raymarine and legacy Autohelm autopilot and instrument systems. It sends rudder-angle feedback to the pilot computer or display so the system can see actual rudder position, and it comes with a 10 m cable and mounting hardware.

On boats that use rudder feedback, this sensor helps the autopilot track steering movement more accurately during setup and normal use. It can also be used on SeaTalkNG instrument systems when connected through an iTC-5 converter.

For Evolution autopilot installations, a rudder reference sensor is essential with ACU-300 systems and recommended on other compatible ACUs. Before ordering, it is worth confirming that your installation uses a rotary rudder reference sensor rather than another feedback style.

Key features

• Rotary rudder reference transducer for compatible Raymarine and legacy Autohelm pilot systems
• Feeds rudder-angle data to the course computer or a compatible rudder angle display
• 10 m cable gives useful routing length from the steering area to the pilot computer or converter
• Can be used on SeaTalkNG instrument networks through an iTC-5 converter
• Essential for Evolution ACU-300 setups and recommended on other compatible Evolution ACUs
• Mounting hardware included for replacement or retrofit installations

Compatibility and fit

This unit is used where the steering system accepts a rotary rudder reference sensor. It is a common replacement when an older feedback unit has failed, or when an autopilot installation needs rudder-angle input added to the system.

It also suits compatible rudder angle display installations. On SeaTalkNG networks, the sensor is connected through an iTC-5 converter rather than directly into the backbone.

Installation and setup

The sensor is mounted mechanically to the steering linkage so its rotation follows rudder movement. The included hardware handles the attachment side, while the 10 m cable gives enough length for many runs from the aft steering area back to the autopilot computer or converter.

After fitting, the rudder reference should be calibrated in the pilot or instrument setup so the indicated rudder angle matches the boat's actual steering position. This matters most on boats where accurate rudder feedback is part of autopilot tuning and day-to-day helm control.

What's included

• Rotary rudder reference transducer
• 10 m cable
• Mounting hardware