M81136 Type 2 Rotary Drive Unit (12V)

The Raymarine Type 2 Rotary Drive (12V) represents a high-power solution for automated steering in larger mechanically-steered vessels. Building on the foundation of the smaller Type 1 unit, the Type 2 is engineered with a more powerful motor and rugged gearing to take on the steering loads of bigger rudders. With a maximum recommended boat displacement of up to 20 tons, the M81136 finds its use in large offshore yachts, long-range cruisers, and even some commercial or military small craft where a reliable heavy-duty autopilot is essential.

Like its smaller counterpart, the Type 2 rotary drive meshes into the helm’s chain-and-sprocket system to drive the wheel. The difference lies in its substantially higher torque output, which allows it to control much larger rudder surfaces. It runs on 12V power but draws higher current – hence it is always paired with the robust ACU-400 control unit capable of delivering the necessary power. Underway, even when faced with heavy steering loads, the unit demonstrates stability and maintains smooth operation, avoiding undue strain on the rest of the steering gear.

A key advantage of the M81136 is its ability to cope with situations like a highly loaded rudder – for instance, fighting strong weather helm or performing emergency maneuvers – without losing grip or stalling. The reduction gears are built from hardened steel, and the clutch is tuned to slip in extreme conditions to protect the motor from damage. In practical terms, if the rudder is slammed hard or encounters an obstacle, the drive’s clutch will sacrifice itself (momentarily slipping) rather than allow the motor to burn out or a chain to break.

In operation, an autopilot system equipped with the Type 2 rotary drive lets the skipper relax even on larger yachts, maintaining the set heading hour after hour. Despite the increased power, noise levels remain low – you’ll only notice a faint hum as it works, preserving the tranquility onboard, which is valuable on larger boats used for extended cruising or liveaboard life.

Use cases: The M81136 is an excellent choice for big sailing yachts (e.g., 50–60 ft bluewater cruisers or maxi racers) that regularly sail under autopilot on long ocean passages, as well as commercial vessels like pilot boats or fishing vessels where the autopilot is engaged for long durations. In these scenarios, the Type 2 drive provides the longevity and brawn needed for steering under various load conditions.

Advantages:

• Increased power for large rudders: If your vessel has a large rudder blade or twin rudders that a smaller drive might struggle with, the Type 2 offers the necessary power reserve. It holds course during aggressive maneuvers or heavy weather without getting overpowered, so even when you’re caught in squalls or maneuvering a hefty boat in tight quarters, the drive responds with authority.
• Integration with high-end autopilot systems: Compatibility with the ACU-400 places this drive in Raymarine’s top-tier Evolution autopilot category. This ensures optimal autopilot performance – from sensor input to drive output – and allows you to leverage advanced features like automatic yaw compensation, integration with wind data for sailboats, and precise track-keeping when following routes on your chartplotter.
• Durability and serviceability: Raymarine has built a high level of durability into the M81136. Internal components are sealed against dust and moisture, and the motor is designed with cooling considerations to permit extended runtime without overheating – crucial for multi-day passages. Furthermore, Raymarine’s global service network means that should you need parts or assistance, you can find support in major ports around the world. This is a big plus for circumnavigators and remote expeditions relying on their autopilot.
• Optimized for heavy conditions: In severe weather (e.g., storms or gale conditions), an autopilot with a Type 2 drive can maintain course better than a less powerful unit. Large waves and strong winds exert high forces on the rudder, but the powerful motor and robust gearbox of the M81136 provide the torque needed to counteract these forces and keep the vessel on track. This relieves the crew from exhausting manual steering at times when conditions are challenging, which can be a critical safety factor.
• Flexible installation: Despite its greater size and power, the unit is still designed with installation flexibility in mind. Multiple mounting orientations are possible, and the drive comes with adjustable mounting brackets to align properly with the chain run and sprocket position. This helps accommodate the drive in various helm configurations, whether you’re retrofitting an older boat or installing it in a new build.

With the M81136 Type 2 Rotary Drive (12V), you gain confidence that your autopilot can handle steering your larger vessel through all conditions. It’s an investment in the safety and comfort of long-distance cruising – a device that works behind the scenes so you can have more freedom to manage sails, navigation, or simply rest. In essence, this drive unit empowers your autopilot to do its job on a grander scale, delivering dependable helm control that lets you enjoy the journey even when Mother Nature throws her worst at you.