6 Best Sailboat Autopilot Systems

Published Categorized as Boats

Hand steering a sailboat is so much fun – until it isn’t. In actuality, it’s tiring work that requires more concentration than we can give it for very long. Racing sailboats switch helmspersons regularly, and offshore passagemakers never rely solely on hand steering. In fact, a breakdown of automatic steering is a big problem for a short-handed vessel offshore.

Sailboat autopilot come to our rescue again and again. These crewmembers don’t need sleep, food, or water, and they never complain much. So let’s take a moment to appreciate these wonders of modern technology, and credit them with what they make possible. Here’s a look at the inner workings of Otto the Pilot, including his care and feeding.

Table of Contents

What is a Sailboat Auto Pilot? How Does It Work?

At the most basic level, the purpose of an autopilot is to steer the boat so you don’t have to. Steering a boat is like steering a car–every bend and curve in even a straight road will set the vehicle on a new course. So while sailing, every wave will wiggle the boat around. What’s more, the boat’s designed-in weather helm tendencies will cause it to want to head up into the wind. So steering a sailboat requires constant attention and work. 

After about 30 minutes, even the best helmsmen will start to waiver. An autopilot relieves you of some of this workload. It allows you to safely stand watch at the helm for hours at a time because you don’t have to worry about every bump, wave, and wind gust blowing you off course.

Do Boats Have Autopilot?

Of course, not every boat has an autopilot. It likely doesn’t need one if the boat is designed for day sailing. Half the fun of day sailing lies in the handling of the boat–the actual sailing part! Having an autopilot might be handy, but it’s hardly a necessity.

But boats that are built to travel for hours, days, or weeks at a time need an autopilot of some sort. There are many types of autopilots out there, even some mechanical ones that require no electricity. They vary in functionality, but their basic purpose is to relieve the helmsperson of some of the work. 

What Can an Autopilot Do?

With that in mind, all autopilots can perform some basic functions. No matter how basic they are, they can all hold the boat’s course and points of sale in a relatively straight line. How they accomplish this depends on their complexity and what sort of sensors or inputs the autopilot has to understand the world around it.

Advanced modern autopilots usually have three modes you can select from. They can hold a compass heading, a bearing off of the wind, or hold a GPS course to the next waypoint. 

sailboat autopilot

What Can’t an Autopilot Do?

As amazing as autopilot is and as much work as they can do for us, they have some very big limits. What can’t an autopilot do? It can never replace an able helmsperson exercising good seamanship.

What does that mean? First and foremost, it is the legal responsibility of every vessel operator to maintain a continuous lookout. This is one of the most fundamental regulations in the COLREGS – the international laws set to prevent collisions at sea. 

In other words, only a human standing watch and looking out for hazards can see and avoid those hazards. An autopilot has no sensors to understand the world around it in that way–it can’t see other ships, boats, landmasses, rocks, or markers. So if it’s holding its course and something is ahead of it, it will run right into whatever lies in its way.

Many new sailors want to know if they can sleep while the autopilot drives the boat. The autopilot will certainly keep driving the boat–but it will keep driving it forever–onto the beach, into the side of a container ship, or straight into a metal day beacon.  

Another thing that autopilots don’t know is when to stop. They keep going until the helmsman switches them into “standby” mode. Here’s a horror story that I’ve heard a few times–it’s the middle of the night, and the boat is on autopilot. The skipper needs to pee, so he walks to the stern rail and falls off. His wife awakes two hours later for her watch, only to find an empty boat that’s still steering a perfect course away from her dear darling husband. 

Now, ladies, before you get any ideas, this is supposed to be an illustrative and cautionary tale about autopilots, not marriages.

Types of Autopilot

Mechanical Windvane

It’s impossible to understand the role and purpose of modern autopilots without first discussing the tried and true mechanical windvane. 

The windvane is a simple item mounted to the back of the boat. Above the water is a windvane that swings to point into the wind. Through a series of linkages, it is attached to a rudder below the water–either its own rudder or attached to the boat’s rudder.

sail boat auto pilot

The skipper uses a line to select the direction off of the wind – using the windvane – that they wish to steer. The windvane then corrects for any changes by moving its rudder left or right. 

The windvane is pretty simple in theory and ultra-reliable. Before the days of solar and wind generators, the fact that they used no electrical power was their biggest selling point. They’re still popular with offshore sailors today, mostly because of their reliability and simplicity. While a lightning strike could take out every electrical component on your boat, it wouldn’t hurt a windvane. 

For all its plusses, the windvane has some limitations. It only works when sailing in steady winds–if you’re trying to hold your course while motoring on a windless day, it won’t do much. They are also large and bulky, mounted on the stern of the boat in a place where most coastal sailors want to have their dinghy or a nice swim step.

Electrical Sailboat Autopilots

Electric autopilots are a technology borrowed from the powerboat world. There’s fundamentally no difference between a sailboat autopilot and one built for a powerboat.  

Above-Deck or Cockpit Autopilots

An above-deck autopilot has all of its components mounted at the helm. It’s a simple and less expensive solution popular with smaller coastal cruising boats. 

For a basic autopilot like this, an electric mechanism will turn your steering wheel or tiller. It works fine on smaller boats and in calm conditions. However, the drive units are not powerful enough to move a big boat or a boat in very rough conditions. These units are commonly called wheel pilot and tiller pilot systems.

Below-Deck or Inboard Autopilot System

The best solution, albeit the more expensive and complicated one, is the below-deck autopilot. The rudder is turned by a series of servo motors or hydraulics below decks.

The biggest advantage of most of these systems is that the autopilot usually has its own attachment to the rudder post. In the event of a steering failure, the autopilot will often still control the boat just fine.

Another advantage is that the autopilot drive motor can be sized correctly for the vessel. Hydraulic rams that produce incredible force can be mounted. These can control any vessel in any sea condition if sized correctly.

Sail Boat Auto Pilot Components

Today’s autopilots are complex electronic systems built of several components that work together to get the job done. Most advanced autopilots consist of the following parts.

  • Control head
  • Electronic flux-gate compass
  • Black box computer or core pack
  • Drive unit
  • Rudder position and other sensors
Raymarine Pilot Ev-400 A/P with P70R No Drive

Control Head

There must be some controls for the helmsperson to manipulate the helm of the boat. This is usually in the form of an instrument-sized control head that monitors and controls the autopilot system. 

Compass

The autopilot computer cannot know the compass course of the boat without having an electronic flux-gate compass. It is usually mounted somewhere in the boat far from other electromechanical systems, like a locker in the stateroom. 

Computer, “Black Box,” or “Core Pack”

The autopilot’s processor will have a central black box that receives input from its various sensors. It also directly controls the drive motor, telling it when to come on and which direction to steer with how much force.

Drive Unit

The drive unit mounts to the rudder post of the boat. It is generally preferred that the drive attach directly to the post so that if anything on the regular steering system breaks, the autopilot will still function. In the case of an above-deck autopilot, the drive unit is usually a simple electric motor or a magnetic servo mounted to the wheel.

There are a few methods of below-deck drive that can be matched to the vessel’s existing steering system. For example, powerboats with outboards often have hydraulic steering installed. In addition, there are autopilot drive systems that you can install in line with this existing system. 

The most common type of drive on sailboats is the linear ram drive. This is a rod that pushes straight in or out. When mounted to an arm on the rudder shaft, it can turn the rudder through its full range of motion.

The ram can be powered by either an electric motor of the sailboat and gears or hydraulics. 

Rudder Angle Sensor

A position sensor is mounted on the rudder shaft to ensure that the autopilot knows the rudder’s angle. It operates an indicator on the control head. But more importantly, it helps calibrate the system to know where the center is and how much deflection is given to each side. 

Other Input Sensors

The complexity of your autopilot is also dependent on how many other electronics are networked into the autopilot computer. Most marine networks now work on the NMEA2000 standard. If that’s the case, and your autopilot talks to your other instruments, you’ll likely get a few extra benefits. 

Wind Angle

If you have an electronic wind instrument onboard, your autopilot will be able to hold a true wind angle. This is a great way to run a cruising boat and like using an old-school windvane. 

For example, you might be running a course to your destination and find it sailing downwind. Instead of risking an accidental jibe with your boat, you set up a course with the wind 160 degrees to starboard. The autopilot will hold that wind angle for you, even if the wind shifts slightly. Then, you can determine when, where, and if you need to jibe.

GPS Course

If your autopilot “talks” to your MFD (multi-function display), you can get even more options. If you plot a course directly to a waypoint, your autopilot can track the sailboat on that line using the “Navigation” function. Remember that it won’t know what to do when you get there, so it will likely deactivate itself. It’s just holding that pre set compass course.

Alternatively, you could program an entire route into your GPS. This series of waypoints, all located in safe water, guides you from departure to destination. Most GPS systems will communicate the turns in the route to the autopilot, allowing it to follow that pre-programmed route without you touching it. 

Picking the Best Sailboat Autopilot

Picking an autopilot for your boat is one of those big undertakings that can quickly balloon out of your control. 

Here’s my own experience installing an autopilot from scratch. I share it here not as a how-to guide but as a cautionary tale into exactly how involved a project that this can become. 

Our sailboat came with a home-built above-deck autopilot. It functioned acceptably in calm waters, but its belt drive was easily overpowered in following seas. It was also something of a hassle to activate and deactivate. So in replacing our GPS and other electronics, we knew we wanted to upgrade to something more able to handle offshore weather.

We settled on B&G electronics for our boat. The existing autopilot had a newer Raymarine control head, compass, and computer, which I hoped to reuse. I wanted to get a linear drive unit to mount below decks. 

While I could get a Raymarine linear drive that would communicate with the Raymarine computer I owned, I could not get one big enough for my boat. So a new black box was required. 

I could not find a hydraulic drive unit that would fit the dimensions of our boat. There wasn’t much space near the rudder, and most hydraulic units were big. So I settled for an electric linear drive from Raymarine, but the most powerful one. 

I then discovered there was no easy way to mount the drive unit. My rudder post did not have an arm for it, so I would have to have that built custom. Plus, there were no flat spaces in the compartment nearby where the drive could be bolted on. 

Thankfully I could mount the Raymarine linear drive at any angle. I had to build angled blocks out of solid wood, allowing the drive motor to be mounted on its side and at a 30-degree angle to the rudder post. I then had a custom-made arm built by Edson Marine with a 30-degree offset, a $600 unexpected expense. This strange and complicated arrangement was the only way I could get the drive to give full deflection of the rudder within its designed mounting limits. 

So, what began as a $1,200 project for a new drive unit ballooned into a complete replacement project with all electronics costing over $4,000, plus another $1,000 in miscellaneous parts and modifications. This is for a 38-foot sailboat and doing all the work myself. The project would have easily cost $10,000 or more had I had a boatyard do the labor. 

How did I choose which autopilot would be best? Well, there aren’t actually that many choices. While many companies make hydraulic rams, only Raymarine had electric linear drives. I already had B&G electronics, so it only made sense to buy the same for maximum compatibility. 

In the end, the system works flawlessly, and I am very happy. But it goes in the folder of boat projects I hope never to do again. So, from one sailor to another, my advice is to buy a boat that is already set up the way you like it! Most newer boats come from the factory set-up for a below-deck autopilot, so all you should ever have to do is replace the components.

Size and Displacement of Your Vessel

The most important factor in choosing your autopilot is to size it correctly according to the boat’s displacement. This will ensure that the unit has enough power to move the rudder when it’s underway. The force needed to move the rudder is proportional to the size of the rudder and the speed at which the vessel is moving. 

For whatever type of drive unit you choose, you will be given some operating limits of what it can and cannot do. For example, Raymarine makes three versions of their mechanical linear drive. Type 1 is for boats up to 24,000 lbs, Type 2S for up to 33,000 lbs, and Type 2L for vessels up to 44,000 lbs. The arms have a stroke of 12 (S model) or 16 (L model) inches, which must accommodate the movement of your rudder from stop to stop. Finally, the physical dimensions of the drive need to fit in the space provided.

Types of Drive Unit

Raymarine makes about the most complete line of autopilot drives on the market today. Currently, Raymarine has five types.

  • Hydraulic pumps for hydraulic steering 
  • Hydraulic linear arms
  • Mechanical linear arms
  • Mechanical rotary motors for chain and sprocket drives
  • Sterndrive actuators for boats with power-assisted steering

The drive unit you choose will be part of your overall system design. It depends on how your steering system works and how and where you’re going to plug in the autopilot drive.

Functionality and Integration with MFD

If you’re installing new electronics with your autopilot, getting a unit that matches the rest of your navigation technology makes sense. If you have Garmin, stick with Garmin; likewise, Raymarine or B&G. All make good products. The benefits of having them work together flawlessly are greater than any benefit you’ll get from mixing and matching different brands.

For example, my B&G autopilot allows me to control the autopilot directly from my MFD instead of having a separate control head. This saved me some money and space at the helm since a control head would be another $500 and another instrument face to mount. It also means that I can use the big touch screen and menu system to set up the autopilot and calibrate it.

Sailboat Autopilot Reviews

When shopping for an autopilot, you may find it difficult to shop online. More often than not, suppliers will have one component you need but not another. No one keeps all of these parts in stock and available for immediate shipment. You’ll wind up piecing together your autopilot system with parts from several sources. 

More often than not, what owners need is to replace one component. For example, maybe the drive unit went bad, or their control head display died. In these cases, simply replace the same part number from whoever has the part.

If you’re replacing the entire system or all of your electronics, it may be easiest to work directly through the manufacturer or their local distributor. However, if you’re willing to shop around, you might be able to find kits and individual components through Amazon, West Marine, Defender, or other marine stores. 

Small Boat Tiller Pilots

Simrad TP10 Tillerpilot

The TP10 is an entry-level, easy-to-use autopilot built for boats with tillers up to 32 feet long. It mounts simply in the cockpit and has easy controls. Best of all, it’s waterproof.

Raymarine ST2000 Plus Tiller Pilot

Raymarine makes a similar line of tiller pilots. This model, A12005, is for vessels weighing up to 10,000 pounds. 

Below Deck Autopilots

Raymarine Pilot EV-400 Autopilot (No Drive Included)

For below-deck mounted systems, Raymarine makes two levels of the computer system–the EV-200 or EV-400. This is the 400, which is big boat approved and will drive their largest Type 3 mechanical or hydraulic drives. Match the correct drive unit to the size and configuration of your vessel. 

This kit also comes with the P70R, a rotary dialed controller for the helmsperson. The knob is a great feature that makes turning the boat in small increments a lot easier. 

Garmin Reactor 40 Corepack for Mechanical or Retrofit Autopilots

Garmin autopilot systems are based around the Reactor 40 “core pack.” Unfortunately, most of Garmin’s autopilot kits available online are designed for modern boats or those with hydraulic steerings systems. To piece together a kit for a classic sailboat with cable or Edson steering, start with this retrofit core pack directly from Garmin.

This kit includes: 

  • Course computer unit
  • GHC20 control head
  • Electronic control unit (ECU)
  • Buzzer
  • Cables and NMEA2000 connectors
Garmin Reactor below deck autopilot

B&G (Simrad) NAC-3 Core Pack and Compass

This kit includes the main computer for the Simrad family of autopilots. You can couple this with any type of drive unit. All controls for the autopilot are accomplished through the B&G Zeus or Vulcan multi-function display. If you want a dedicated control panel, they sell that as well. You may also need a rudder position sensor to make the system work.

Furuno NAVPILOT300

This is an all-in-one solution that requires fewer parts. You’ll still need a drive unit and a heading sensor to make a complete system. 

Sailboat Autopilot FAQs

Top Brands of Sailboat Auto Pilot

As mentioned above, the big names in sailboat instruments all offer autopilot packages. If you’re only replacing the autopilot electronics, keeping everything the same brand makes sense. However, if you’re replacing everything, you have bigger choices to make. 

Garmin

Garmin applies the lessons they learned by making several generations of aircraft autopilots. Their systems integrate much more than a simple flux-gate compass–their autopilots are built with a full-fledged AHRS (Attitude Heading Reference System).

Using this Autopilot Compatibility Guide, you can figure out which Garmin autopilot is right for you.

Navco is the parent company of three different electronics brands–B&G, Simrad, and Lowrance. That’s a perk because you can mix and match components between the three names at will. B&G is the favored brand for sailboats. The B&G NAC-2 and NAC-3 autopilot computers are the basic start for the typical cruising yacht. High-end racers and luxury boats will want to look into the fancier H5000 autopilot system. 

Simrad sells a line of basic tiller pilots for above-deck autopilot installs on small boats.

Raymarine

Raymarine is one of the older and most trusted brands in marine electronics. Their autopilots are robust and come in any arrangement you like. In addition, they have one of the only above-deck wheel-drive autopilot systems on the market, the EV-100 SAIL. They also have tiller pilots and a complete lineup of below-deck options.

Furuno

Furuno is an underdog in the recreational marine industry – favored by professionals but often overlooked by the private boat owner. Their autopilot NAVPILOT offerings are adaptive controllers designed to make boat handling easier. Most are designed for outboard hydraulic-steer fishing boats, but their control heads and computers will work with almost any type of setup.

How much does a sailboat autopilot cost?

The cost and complexity of an autopilot system depend on the size of the boat. Small tiller-steered daysailors can usually at a tiller pilot for less than $1000. 

A below-deck autopilot, with all of the components to make it work with your multi-function display, will set most owners back $4,000 or $6,000. In addition, if the boat does not already have a below-deck autopilot, there may be quite a bit of labor necessary to build platforms or brackets to adapt the drive unit to the rudder post.

Do sailing yachts have autopilot?

Yes, most sailboats larger than daysailers have autopilots. These vary in complexity from mechanical windvanes to extensive electronic systems that tie into the boat’s GPS and multi-function displays.

Can you sleep while your boat is on autopilot?

A good autopilot will steer a boat for you, on a constant heading or wind angle, through nearly any conditions. However, it cannot ensure that you don’t hit anything–like another vessel. It is illegal to operate a vessel without a “proper look-out by sight and hearing as well as by all available means appropriate…to make a full appraisal of the situation and or the risk of collision” (COLREGS Rule 5).

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