The Helmsman's Friend -
A Sailboat Autopilot

A sailboat autopilot is a thirsty beast, drinking your battery juice as if its life depended on it - which of course it does. So is it best to forego one of these and hand steer all day, for mile after mile, hour after hour? I don't think so...

So, providing your boat's batteries can keep up with its electrical appetite, an autopilot deserves a place on any sailboat, large or small.

Whilst larger boats will need a powerful inboard type working directly on the primary steering mechanism, one of the cockpit models will suit the smaller boats.

There are two cockpit versions of autopilots - one for wheel-steered boats and another for tillers.

All types rely on fluxgate compasses keep them on the straight and narrow.

Cockpit Versions of Sailboat Autopilots

A Raymarine Tiller Pilot

For Tiller-Steered Sailboats

Autopilots for tiller steered vessels - or 'tillerpilots' as they are widely known - are the simplest form of sailboat autopilot, in which an electric motor is connected via a transmission mechanism directly to a push rod. The push rod extends or retracts to move the tiller.

Small tiller-pilots, suitable for boats up to around 4,500kg displacement, consist of a single module which includes the compass, the control unit, the motor and push rod.

In larger models, suitable for boats up to around 7,500kg displacement, the control unit and compass are separate modules. All tiller autopilots tend to be a little noisy - rather like the distant yapping of a small dog.

Popular Tiller Pilot Brands and Models:

Raymarine:

ST1000+: Suitable for sailboats up to 3,000 kg (6,600 lbs) displacement. It's a popular entry-level model known for its ease of use.

ST2000+: For slightly larger sailboats, up to 4,500 kg (10,000 lbs) displacement, offering more thrust.

EV-100 Tiller: Part of Raymarine's Evolution series, it uses a more advanced EV-1 sensor core for intelligent steering and is suitable for boats up to 6,000 kg (13,200 lbs) displacement. This often comes as a complete pack with the sensor, control unit, and drive.

Simrad:

TP10: Designed for yachts up to 10 meters (33 feet) in length with a maximum displacement of 3,700 kg (around 8,150 lbs).

TP22: Suitable for boats with tillers up to 11 meters (36 feet) overall length and a displacement of around 5,000 kg (11,000 lbs).

TP32: For larger tiller-steered boats up to 12 meters (39 feet) and a displacement of approximately 6,300 kg (13,900 lbs).

Key Features of Tiller Pilots:

Self-Contained Units: Tiller pilots typically integrate the drive mechanism (an electric ram), compass, and control unit into a single, compact housing that mounts directly to the tiller.

Direct Steering Action: They work by extending or retracting a pushrod connected to the tiller, directly moving it to control the rudder.

Easy Installation: Generally designed for relatively straightforward DIY installation with a mounting socket on the coaming or seat and a pin on the tiller.

Power Consumption: They run on 12V DC power, and power consumption varies depending on the model and steering demands. Standby current is usually low, but it increases when actively steering.

Connectivity: Many modern tiller pilots offer connectivity with other onboard instruments like GPS and wind instruments via SeaTalk or NMEA 0183/2000, allowing for features like track steering and wind vane mode.

Thrust and Displacement Ratings: Manufacturers provide recommended maximum boat displacement figures for each model. It's crucial to consider your boat's fully laden displacement.

Stroke Length: This specification indicates the maximum travel of the pushrod, which affects the maximum rudder angle the pilot can achieve.

Waterproof Rating: Tiller pilots are designed for cockpit use and typically have a degree of waterproofing (e.g., IPX4).

When choosing a tiller pilot, consider your boat's size and displacement, the typical conditions you sail in, and whether you need advanced features like GPS tracking or wind steering integration.

For Wheel-Steered Sailboats

Autopilots for wheel steered vessels are very similar to the tiller version, except that course corrections are applied to the wheel by a belt, rather than a pushrod.

Many offshore sailors choose to equip their sailboats with both windvane self-steering gear and an electronic autopilot - the former to steer the boat when sailing and the latter for use under power, when the electrical supply will be plentiful.

Popular Wheel Pilot Brands and Models:

Wheel-steered boats use autopilots that apply course corrections via a belt system rather than a push rod. Offshore sailors often opt for both windvane self-steering gear and an electronic autopilot—using the former while sailing and relying on the latter when motoring, when electrical supply is abundant.

Raymarine:

EV-100 Wheel Pilot: This is a complete autopilot solution designed for wheel-steered sailboats up to around 7,500 kg (16,500 lbs) displacement. It features an intelligent EV-1 sensor core and a wheel drive unit that mounts directly to the steering wheel. It's often available as a pack with a P70s control head.

Cockpit MkII Wheel Drive: A robust wheel drive unit designed for sailboats up to 7,500 kg (16,500 lbs) displacement. It clamps directly to the steering wheel and has an adjustable clutch lever for easy switching between autopilot and manual steering. It typically works with an ACU-100 control unit and a compatible control head.

Garmin:

Reactor 40 with Wheel Drive: Garmin offers various Reactor 40 autopilot systems, and a common configuration for wheel-steered boats includes a wheel drive unit. The Reactor 40 is known for its responsive performance and integration capabilities with Garmin chartplotters. You would typically select a corepack (including the CCU/ECU and potentially a heading sensor) along with the wheel drive.

B&G:

While B&G offers high-performance autopilot systems often integrated with their instrument packages, specific "wheel pilot packs" in the same vein as Raymarine or entry-level Garmin might be less emphasized. B&G systems for wheel-steered boats would typically involve a core autopilot computer (like the NAC-2), a wheel drive unit (which might be sourced from Simrad as they are part of the Navico group), and a B&G control head (like the Triton Pilot controller).

Simrad:

SD10 Mechanical Drive Unit: Simrad (also under Navico with B&G) offers mechanical drive units designed for wheel steering systems and compatible with their autopilot computers like the NAC-2. These drive units typically clamp onto the steering cable.

Key Features of Wheel Pilots:

Wheel Drive Unit: The core of a wheel pilot is the drive unit, which typically uses a belt or a direct drive mechanism to turn the steering wheel. These units are designed for relatively easy installation in the cockpit.

Control Head: Wheel pilot systems include a control head mounted within reach of the helm, allowing you to engage/disengage the autopilot, set course, and adjust parameters.

Course Computer (ACU/ECU/NAC): This is the "brain" of the autopilot, processing data from sensors and issuing commands to the drive unit.

Heading Sensor (Compass): A fluxgate or solid-state compass provides the autopilot with the boat's heading. More advanced systems may use rate gyros for improved performance.

Integration: Modern wheel pilots often integrate with GPS, wind instruments, and other navigation electronics via NMEA 2000 or SeaTalkNG, enabling features like track steering and wind vane mode.

Displacement Rating: Similar to tiller pilots, wheel pilots have recommended maximum boat displacement ratings. Choose a model appropriate for your boat's fully loaded weight.

Clutch Mechanism: Many wheel drives have a clutch that allows you to easily switch between autopilot control and manual steering.

When selecting a wheel pilot, consider your boat's size and displacement, your budget, the level of integration you desire with other onboard electronics, and the features that are important for your type of sailing.

Inboard Sailboat Autopilots

Powerful and fully integrated with onboard navigation systems, inboard autopilots are designed for larger sailing yachts and powerboats. Instead of connecting to the wheel or tiller, they operate via push rods or hydraulic systems linked directly to the rudder post or quadrant. With more advanced functionality, these systems often carry a higher price tag but are indispensable for serious sailors.

A Fully Integrated Sailboat Autopilot System

The trend toward instrument system integration has extended to cockpit autopilots with separate control/display units. By connecting to compatible GPS and wind instruments, these systems offer three main operating modes:

Auto: The autopilot locks onto a heading.

Track: The autopilot follows a track between two waypoints.

Wind Vane: The autopilot maintains a course relative to the apparent wind.

A Fully Integrated Sailboat Autopilot System

A typical, fully integrated system

While convenient, using masthead or stern-mounted wind instruments in choppy conditions can yield unsatisfactory results due to boat motion or disturbed airflow. Modern systems damp and process these impulses to deliver a usable signal.

Beyond steering, the display unit offers various alarms—like cross-track error, waypoint proximity, and windshift alarms—and handy functions such as 'Autotack,' which automates tacking so short-handed crews can focus on sail adjustments.

Feeding the Beast

Power consumption of an electronic sailboat autopilot can be significant, the key factors affecting it being:

Sail trim: poorly trimmed sails and excessive weather helm;

Sea state: bigger seas and increased yawing require more frequent steering adjustments;

Autopilot setting: the more precise the course setting, the greater the work to be done by the autopilot;

Boat displacement and waterline length: the more boat there is to move, the greater the greater the work to be done by the autopilot;

Underwater shape: notwithstanding the tracking properties of a long-keeler, a keel-mounted rudder will require more force because it's impossible to balance, whereas a fully balanced spade rudder will be lightest on the helm.

Your charging system needs to be robust; any weakness, and the autopilot will soon expose it.

If energy consumption is a concern, you might want to explore modern autopilots equipped with energy-saving features. Solar-powered options can extend your battery life, and systems with intelligent power modes optimize usage, making them ideal for long journeys.

Linking a Tiller Pilot and a Vane Gear.

By removing the windvane from a vane-gear and connecting a small tiller autopilot in its place you can now use a vane-gear when under power. The pendulum or trim-tab now works with the autopilot, greatly reducing power consumption.

Some windvane gears, like the Auto-Helm and the Windpilot Pacifics for example, are constructed with this in mind and have the connection fitting built in. Other vane gear manufacturers don't recommend this approach, believing that the turbulence of the prop-wash can damage the pendulum blade bearings.

Latest Innovations and Features

Autopilots are evolving into more advanced systems, some equipped with AI that responds dynamically to changing sea conditions. These systems adapt their sensitivity based on factors like wind or wave height, making steering smoother and more accurate.

Many modern autopilots also offer app integration, allowing remote control and monitoring from smartphones or tablets—perfect for when you’re managing multiple tasks or relaxing away from the helm.

Safety Enhancements

Sailors today have access to autopilots with advanced safety features, including fail-safe mechanisms that revert to manual steering in case of malfunction. Manual overrides ensure quick responses during emergencies, giving peace of mind even in challenging conditions.

Cost and Compatibility

Prices vary widely, from under £500 for basic tiller models to several thousand pounds for high-performance integrated systems. While more expensive options may seem daunting, consider the long-term savings through improved efficiency and durability. Compatibility, on the other hand, is crucial. Before purchasing, check if the autopilot integrates seamlessly with your existing GPS, wind instruments, or navigation systems to avoid installation headaches.

Environmental Impact

For eco-conscious sailors, newer autopilots with energy-saving modes or solar power capabilities offer a sustainable way to navigate. These systems reduce reliance on traditional power sources and contribute to lower environmental impact—something every sailor can appreciate when out on the open water.