Single vs Dual Motor Autopilot Drives: How to Choose

What drive motors do in an autopilot

The drive unit is the physical part of an autopilot that moves the steering. Raymarine's product page describes the drive unit as the part that interfaces with the vessel's steering system to keep you on the right course. Inside that drive unit, an electric motor powers a pump, a linear actuator, or a rotary gear. The number of motors in that unit is what this article compares. See autopilot drive types for a deeper look.

On a listing, you will see names like 'Type 1 hydraulic pump' or 'linear drive'. These names describe the drive mechanism, but they do not always tell you how many motors are inside. Some listings also say 'autopilot drive unit' without specifying. The motor count is often not in the title, so you may need to ask the seller or the dealer. Compare complete autopilot packs to see how listings name their drives.

Single motor drives: the common configuration

A single motor drive uses one electric motor. It is the most common arrangement on recreational boats. It is simpler to install because there is less wiring and fewer components. It also draws less electrical power than a dual motor setup, because only one motor draws current when the drive operates. For a small sailboat, a tiller pilot is a typical single motor option.

The main limitation of a single motor drive is that it has one point of failure. If that motor fails, the autopilot cannot steer the boat until the motor is repaired or replaced. For many day boaters and coastal cruisers, that risk is acceptable because a motor failure is rare and steering manually is still possible.

• Simpler installation and wiring
• Lower electrical power draw
• Single point of failure
• Usually enough for small to mid-size boats

Dual motor drives: redundancy and extra force

A dual motor drive uses two electric motors. In some configurations, the two motors are connected to the same pump and work together to produce more force or faster movement. In other configurations, the second motor is a backup that only engages if the first motor fails. The second motor may be a separate pump attached to the same hydraulic circuit. This adds a level of redundancy that a single motor cannot offer.

The main benefit of a dual motor drive is redundancy. If you run long distances with the autopilot engaged, a backup motor can keep the autopilot working if one motor fails. The trade-offs are a higher power draw, more complex wiring, and a larger footprint. Dual motor drives are more common on larger vessels with hydraulic steering, but they are also available for some smaller boats. See hydraulic autopilots for examples.

Power draw and electrical planning

The electrical power needed by an autopilot drive depends on the motor count and how often the drive operates. A single motor draws current only when it is moving the steering. Two motors draw more current, especially when both are running. On a boat with limited battery capacity or a small charging system, that extra draw can be significant. The Furuno NavPilot 300 lists '12-24 VDC' as its power usage, but it does not give an amperage figure; that level of detail is often left to the manufacturer's manual. For more on electrical considerations, see autopilot power consumption.

Before choosing a dual motor drive, consider your boat's electrical system. The maker's manual and a qualified installer can help you determine whether your battery bank, alternator, and wiring can support the extra load. You may need a larger fuse and heavier gauge wire for a dual motor setup. The installation guide from the manufacturer should always be the first reference.

Redundancy considerations

Redundancy means having a second motor that can take over if the first one stops. It is not a guarantee that you will never lose steering, because the system still relies on the pump, the rudder reference, and the control electronics. For many boat owners, a single motor is dependable enough. For others, the extra cost and complexity of a dual motor drive are worth the added assurance.

The U.S. Coast Guard Boating Safety Division emphasizes that boat operators are responsible for keeping a proper lookout and for being prepared for emergencies. An autopilot, whether it has one or two motors, does not replace that responsibility. You still need to watch for traffic, obstacles, and changes in conditions. Redundancy is a way to keep the autopilot operational after a motor failure, but it does not reduce the need for an attentive operator.

Choosing the right configuration for your boat

The right motor configuration depends on your steering system, how you use the boat, and the electrical capacity on board. If your boat has hydraulic steering, a single motor hydraulic pump is often enough for a day boat or a coastal cruiser. A dual motor pump can be a good choice if you plan long passages or want a backup. If your boat has a mechanical cable system, a linear drive with a single motor is the typical option. The marine autopilot reviews on this site compare drives on stated details.

Compare listings on this site by looking at the drive type and the control head that is included. The number of motors is not always stated, so a direct question to the seller or the maker may be needed. If you already have a drive, a core pack might let you keep it and add a new control head. The guides below will help you focus on the features that matter for your boat.

What to pick for your situation

Questions

What is a single motor autopilot drive?

A single motor drive uses one electric motor to power the pump or actuator. It is the most common type and is simpler and lower in power draw than a dual motor setup. See tiller pilots for a small boat example.

What is a dual motor autopilot drive?

A dual motor drive uses two electric motors. They can work together for more force, or one can serve as a backup. This adds redundancy but increases power draw and complexity.

Does a dual motor drive use more electricity?

Yes, because two motors draw more current than one. The exact difference depends on the motor specifications and how often the drive operates. Check the maker's manual for wiring and fuse requirements.

Is a dual motor drive always better?

Not necessarily. It adds redundancy, but also cost, weight, and wiring. For many boats, a single motor is enough. The choice depends on your use case and electrical capacity.

Can I add a second motor to my existing drive?

That is not a typical upgrade. It may be possible if your drive unit is designed for it, but it is usually easier to choose a dual motor drive at the start. Consult the maker or a dealer for compatibility.