Simrad RF300 Rudder Feedback Unit is a critical component for achieving smooth, accurate steering in inboard-engine autopilot systems. By providing high-resolution data on your rudder's exact angle, it allows your autopilot computer to make precise adjustments that keep you on course. Simrad Yachting Essential Installation Steps

Proper installation ensures long-term reliability and prevents common "Rudder Feedback Failure" errors. B&G RF300 Rudder Feedback Unit | Autopilot - Simrad

Simrad RF300 Go to product viewer dialog for this item. is a high-resolution, rotary rudder feedback unit that converts mechanical rudder movement into a variable frequency digital signal for autopilot computers. Core Installation Requirements

Mechanical Connection: The unit must be mechanically linked to the rudder tiller arm or quadrant. It is critical that the center of the

is aligned with the center of the rudder post for accurate measurement.

Factory Calibration: Do not attempt to remove the transmitter arm from the feedback unit; it is factory-adjusted and only requires external setup as described in the Instruction Manual. Mounting Orientation: The

can be mounted horizontally, vertically, or upside-down, provided it is on a stable platform. Installation Steps

Alignment: Set the rudder tiller arm to the approximate center position. Rotate the

transmitter lever until its alignment mark is opposite the cable entry into the unit.

Mechanical Linkage: Drill and tap the rudder tiller arm (typically using a 4.2 mm drill and 5 mm tap). Attach the ball joint to the tiller and connect the transmitter rod between the tiller and the

Final Positioning: Secure the unit with provided screws. If necessary, use blocking material under the unit to ensure the transmitter lever is level with the rudder tiller arm.

Wiring: The unit typically uses a two-wire frequency interface for direct connection to autopilot computers. Refer to your specific autopilot computer manual (e.g., Robertson Junction Units) for correct terminal assignments, often terminals 11 and 12. Technical Specifications Interface Two-wire variable frequency Supply Voltage 12–16V DC (via CAN or computer) Waterproof Rating IPx6 (Rugged/Sealed) Cable Length Comes with 10 meters (33 feet) Operating Temp -10°C to +55°C (+32°F to +131°F) Troubleshooting & Calibration DD15 Direct Drive Installation Manual - info-mediawinkel

Preparation:

Turn on the autopilot system but disable the drive (so the rudder does not move unexpectedly).
Access the "Rudder Feedback Calibration" menu. On Simrad systems, this is typically under: Settings > Installation > Autopilot > Rudder Feedback.

4. Tools Required

19 mm (3/4") open-end wrench or adjustable wrench
Marine-grade sealant (e.g., Sikaflex 291i or 3M 4000 UV)
Phillips screwdriver (if using rail mount adapter)
Multimeter (for continuity test)
Soft cloth and isopropyl alcohol (for cleaning)

The Verdict Up Front

The Simrad RF300 is a robust, cable-based wind instrument, but it is from an older generation. The installation manual is technically accurate but can be confusing for modern users accustomed to "plug-and-play" NMEA 2000. If you are installing one today, you are likely replacing an older unit or maintaining a legacy system.

Here is a solid review of the installation process, highlighting the critical points the manual covers (and where it often trips people up).

1. Mechanical Installation: The "Twist-Lock" Challenge

The RF300 is distinct from its successor, the IS300, primarily in how it mounts.

The Manual: The instructions clearly depict the "twist-and-lock" mounting base. You are instructed to screw the base plate to the mast, feed the cable through, and then twist the unit onto the base.
The Reality: This is often the point of failure during a DIY install.
- Alignment: If the base plate isn't perfectly aligned with the vessel's centerline (fore-aft), your wind direction data will be permanently offset. The manual tells you to align it, but in practice, doing this 50 feet up a mast is difficult.
- The O-Ring: The manual mentions the rubber gasket/seal. Do not ignore this. If this isn't seated properly, water will wick down the cable into the junction box, causing the classic "wind speed drops to zero" failure mode.

2. System Requirements and Components

Before installation, the technician must verify the contents of the RF300 package and ensure compatibility with the vessel’s steering system.

2.1 Package Contents

RF300 Rudder Feedback Unit
Mounting bracket (slotted for adjustment)
Linkage arm kit (rosette rod and ball joints)
Mounting screws and washers
Installation manual (for pinout reference)

2.2 Compatibility The RF300 is designed for use with Simrad autopilot systems. It interfaces via a dedicated rudder feedback cable (typically Simrad part numbers 000-08955-001 or similar, depending on the length required). It is compatible with both 12V and 24V DC systems, as the autopilot computer provides the excitation voltage.

3. Tools and Safety Equipment

To perform a standard installation, the following tools are required:

Power drill with appropriate drill bits (for mounting holes)
Screwdrivers (Phillips and flathead)
Wrench or socket set (typically metric or SAE depending on vessel hardware)
Multimeter (for continuity and voltage testing)
Cable ties and marine-grade sealant (e.g., 3M 5200 or silicone)
Safety glasses

Safety Precaution: Always disconnect power to the autopilot system before beginning installation to prevent short circuits or unintended system activation.

Why the RF300 Matters in a Modern Autopilot System

Before diving into the mechanics of installation, it’s crucial to understand the role of the RF300. Unlike a simple rudder indicator, the RF300 provides continuous, linear feedback to the autopilot computer (e.g., Simrad’s NAC series or AC series). This feedback loop allows the autopilot to make micro-adjustments to steering commands, preventing the characteristic "sawtooth" pattern of an overcorrecting autopilot.

The official Simrad RF300 installation manual emphasizes that this sensor is designed for vessels where a direct mechanical link to the rudder quadrant is available. It is rated IP66 for water ingress protection, but its longevity depends entirely on a mechanically sound and electrically clean installation.

9. Specifications

Frequency: 156–163 MHz
Gain: 3 dBi (typical)
VSWR: ≤ 1.5:1 at 156.8 MHz, ≤ 2.0:1 across band
Max input power: 50 W
Impedance: 50 Ω
Polarization: Vertical
Radome material: UV-stabilized fiberglass
Operating temperature: -30°C to +70°C (-22°F to +158°F)
Weight: 0.45 kg (1.0 lb)
Length: 0.9 m (35.4 in)

Simrad Rf300 Installation Manual //top\\ May 2026