Autopilot Noise: How Loud Is the Drive

Why drive noise matters for comfort

When a marine autopilot is running, the part you are most likely to hear is the drive. The drive is the unit that moves the steering: a linear drive pushes a ram, a rotary drive turns the wheel, and a hydraulic pump moves fluid to the steering ram. The control head and the heading sensor have no moving parts of that kind, so the drive is where the sound comes from. For an overview of how each drive works, see the drive types explainer.

Noise matters because the drive is mounted on or near the space where you spend your time. On a sailboat, a tiller pilot sits in the cockpit. On a powerboat, a hydraulic pump is often tucked near the helm or in a compartment. When the autopilot corrects the course, the drive runs, and in a quiet anchorage that sound is easy to notice. The sailboat autopilot guide and the powerboat autopilot guide compare listings by the steering type each drive suits.

This article explains the character of the three common drive types in general terms. The source pages used here name the drive types and the steering systems they suit; they do not publish sound measurements. Sound also depends on the boat's build, the mounting, and how often the drive runs, so no listing can promise a particular noise level.

Linear drives: the sound of a moving ram

A linear drive is a self-contained unit with an electric motor and a ram that extends and retracts to move the steering. As the motor turns, you hear mechanical sounds from the motor and the moving parts. The sound is a working hum or a faint mechanical noise while the drive is moving.

Linear drives are named for the way they push in a straight line. The Raymarine drive unit page lists the Type 1 Linear Drive Unit as a mechanical linear autopilot drive. A listing that names a linear drive tells you the drive type, not how loud it is in your boat.

Where the drive is mounted makes a difference in what you hear. A drive bolted to a solid bracket in a compartment may be less noticeable than one mounted in a way that lets sound travel into the cabin. The maker's manual and a qualified installer are the people to ask about mounting.

Rotary drives: the sound of a turning wheel

A rotary drive uses an electric motor to turn the boat's wheel through a belt or gear arrangement. The sound is similar in character to a linear drive: you hear the motor and the mechanical parts moving as the drive works.

A listing that names a rotary drive tells you the drive turns the wheel rather than pushing a ram. The Raymarine drive unit page names Type 1 and Type 2 Rotary Drives as electric rotary autopilot drives. The same rule applies: the listing names the type, not a sound level.

For a wheel-steered boat, the rotary drive is usually mounted near the steering pedestal. Sound, therefore, is close to where the helmsman sits. Ask the seller or your dealer about the mounting and the bracket included in the pack.

Hydraulic pumps: a whine while they run

A hydraulic pump moves steering fluid to the boat's hydraulic steering ram. When the pump runs, it makes a whine or humming sound that lasts only while fluid is moving. The pump runs when the autopilot calls for a course correction, so it is intermittent rather than continuous.

Hydraulic pumps are named by size on the Raymarine drive unit page, such as Type 1 or Type 2 Hydraulic Pumps, and they are matched to the boat's steering system. A hydraulic autopilot listing usually names the pump that is in the box, which is the piece that makes the sound. The hydraulic autopilot guide compares these listings on the pump type and the steering system.

The pump is often installed near the helm or in a compartment, and the way it is mounted affects how you hear it. A pump that is well isolated may be less noticeable than one mounted directly against a panel. Questions about mounting belong with the maker's manual and a qualified installer.

What a listing can and cannot tell you about noise

The source pages used for the guides on this site name drive types, steering systems and what is in the box. None of them publishes a noise figure in decibels. A listing cannot promise that one drive is quieter than another.

What you can compare on stated details is the drive type, the steering system it suits, and whether the pack includes a control head and a drive. Those details tell you which kind of sound to expect in general terms: a mechanical hum from a linear or rotary drive, or a hydraulic whine from a pump.

The best marine autopilot guide compares the full pool of listings on stated details. If you are choosing between a hydraulic pump and a linear drive, the hydraulic versus linear comparison explains the difference in how each drive works.

Mounting, brackets and where you sit

The same drive can sound different on two boats, because the hull, the mounting surface and the distance from the helm all affect what you hear. A drive mounted far from the cockpit may be barely noticeable; one mounted under the helm seat is right next to you.

When you read a listing, look for what the pack includes in the way of brackets and mounting hardware. The Raymarine pack pages list the components of each pack, and the drive unit page lists the drive types. The manual covers the mounting details, and installation is the work of a qualified installer or dealer.

If noise is a concern for you, ask the seller or your dealer these questions:

• Which drive type does the listing name?
• Does the pack include the mounting bracket for your steering system?
• Where does the maker's manual say the drive should mount on your boat?
• Who will install the drive and check the mounting?

Noise and keeping watch

An autopilot steers the boat while you are on watch, but it does not replace a lookout. The U.S. Coast Guard Boating Safety division provides boating safety information and emphasizes the operator's responsibility to operate the boat safely and to keep watch. A drive that makes noise while correcting course should not distract from that duty.

This site makes no safety claims about autopilots. The article's advice is limited to comparing stated details and asking the right questions of a dealer or installer.

What to pick for your situation

Questions

Which drive type is the quietest?

The source pages do not publish sound measurements, so the guides cannot rank drive types by noise. Each type makes a different kind of sound in general terms: a linear drive makes mechanical motor and ram sounds, a rotary drive makes motor and belt sounds, and a hydraulic pump makes a whine while it moves fluid. What you hear in your boat also depends on mounting and how often the drive runs.

Does a hydraulic pump run all the time?

No. In general terms, a hydraulic pump runs only when the autopilot calls for a course correction and the pump moves steering fluid. When the boat is holding course without correction, the pump is not running.

Does the control head make any sound?

The control head has no moving parts of the kind a drive has, so the sound you hear while the autopilot works comes from the drive. The control head may have an alarm or a keypad click, but those are separate from drive noise.

Can the drive noise be reduced?

Mounting plays a large part in what you hear. The maker's manual covers the mounting details, and a qualified installer can advise on bracket placement for your boat. No listing can promise a particular sound level.

Why do listings not include a noise figure?

The source pages used here name drive types and steering systems, but they do not publish decibel figures. A listing describes what is in the box, not how the drive will sound in your hull.

Does an autopilot replace a lookout?

No. An autopilot keeps the boat on a heading, but the operator remains responsible for keeping watch. The U.S. Coast Guard Boating Safety page provides boating safety information and education resources.