Linear Drive Stroke Length: Match Rudder Travel
Short answer: The stroke length of an autopilot linear drive is the distance its rod travels from fully retracted to fully extended. That reach must cover the full travel of your rudder, outboard, or steering ram, plus the space the mounting geometry needs. A stroke too short limits steering travel; one too long can strain the linkage. Listings do not always state the stroke, so check the maker's page or manual, and ask the seller when a detail is missing. This article explains what to read and what to ask before you choose.
What a linear drive is
A linear drive is a type of autopilot drive unit. It moves a rod in a straight line to push and pull the steering linkage, so the boat changes heading under autopilot control. On a listing, the drive type is one of the first things to read.
The name "linear" describes the motion: back and forth along one axis. That is different from a rotary drive, which turns a wheel or shaft, and from a hydraulic pump, which moves fluid to push a cylinder. For a closer look at the drive families, see drive types explained.
What stroke length means
Stroke length is the distance the linear drive rod travels from fully retracted to fully extended. It is the reach of the drive, and it describes how much movement the drive can deliver to the steering.
The stroke is a separate detail from the force a drive can produce. Two drives can use the same type of motion but have different reach, and the reach is what has to fit your rudder travel.
Why the stroke must match rudder travel
The rudder, outboard motor, or sterndrive has a full range of movement from one hard-over position to the other. The drive has to move the steering through that whole range so the autopilot can steer the boat as far as the helm can.
If the stroke is shorter than the travel the steering needs, the drive runs out of reach before the rudder reaches full lock. The boat then steers less far under autopilot than the helm allows.
If the stroke is longer than the steering travel, the drive can push the rudder past its mechanical stop or strain the linkage. The goal is to match the stroke to the rudder travel plus the mounting geometry. The geometry matters because the angle and length of the linkage change how much rudder movement each part of the stroke produces.
How your steering type decides the drive
The steering already on your boat decides which drive family you look at. A hydraulic steering system usually takes a hydraulic pump drive. A mechanical or cable system can take a linear drive. The maker's page and the autopilot pack descriptions name the steering types each drive is built for.
Raymarine, for example, lists a Type 1 Linear Drive Unit as a mechanical linear autopilot drive. The same maker's pack pages describe sail and power packs for different steering systems. When you compare listings, the steering type named in the listing is part of the answer.
If your steering type is unclear, the questions to ask are simple: what steering system is on the boat, and what does the maker's manual say about it. A dealer can confirm it. See hydraulic steering autopilots if your boat uses hydraulic steering.
What a listing states about the stroke
Listings name the drive type, the model line, and often the pack contents. Stroke length is not always in the title or the bullet list. A listing that omits it is not broken; it is a listing that needs a question.
A missing detail is a reason to ask the seller for the maker's data sheet or manual, not a reason to guess. The same rule applies to the rudder reference: some listings include it, some leave it out.
- Does the title name the drive type and the model line?
- Does the bullet list state the stroke length?
- Does the maker's page for that drive unit give the stroke?
- Which steering type does the maker's page say the drive fits?
| Listing detail | What it tells you |
|---|---|
| Drive type in the title | Tells you the motion is linear, rotary, or hydraulic |
| Model line name | Tells you which product family the drive belongs to |
| Stroke length in the bullet list | Gives the reach of the drive, if the maker states it |
| Steering type named | Shows which steering layout the drive version is meant for |
| Missing stroke length | A question for the seller or the maker's page, not a guess |
How stroke relates to rudder feedback
The autopilot needs to know the rudder position to steer accurately. That is the job of the rudder reference or feedback unit. The stroke length and the feedback are different details, but they work together: the drive moves the steering, and the feedback reports where the rudder is.
Some autopilot lines do not need a physical feedback unit. Furuno describes Fantum Feedback as software that allows outboard and sterndrive installations to work without a physical rudder feedback unit. For other systems, the rudder reference is part of the pack or an extra. Rudder feedback sensors explains the difference.
Questions to ask before you choose
Before ordering, you need three things: the steering type on your boat, the full rudder travel, and the stroke of the drive you are considering. The full rudder travel is a question for the boat and the steering maker; the stroke is a question for the autopilot maker.
The maker's manual is the source for fit and installation. This site and the buying guides compare listings on stated details; they do not provide installation instructions. A qualified installer or a dealer can confirm the fit for your boat.
- What is the stroke length of this drive unit?
- What is the full travel of my rudder or steering ram?
- Which steering type does the maker's page name for this drive?
- Does the pack include a rudder reference, and does the system need one?
- Which drive version does the maker's page recommend for my steering?
What the guides compare on stated details
The buying guides on this site compare autopilot listings on stated details: the steering type named, the boat type, the drive in the box, the control head in the box, and the model line. When a listing does not state the stroke, the guides do not invent a figure. The maker's page and the maker's manual are the sources for stroke length.
A linear drive is one part of a networked autopilot system. Modern autopilots share data over a network such as NMEA 2000, which the NMEA describes as a standard for connecting marine electronics. The drive does its work on the steering, and the control head talks to the rest of the system over that network.
Whatever you choose, an autopilot does not replace a lookout. The U.S. Coast Guard Boating Safety page is the general source for boating safety and responsibility on the water. Keep watch while the autopilot steers, and use the guides to build a shortlist before you ask a dealer about fit. See complete autopilot packs and core packs to start.
What to pick for your situation
| If you | Pick | Buying guide |
|---|---|---|
| Your boat has mechanical or cable steering and you want a linear drive | Compare complete packs that include the drive in the box | Best Complete Autopilot Packs (2026): 13 Picks Compared |
| You plan to keep an existing drive and only change the electronics | A core pack listing | Best Autopilot Core Packs 2026: 12 Picks Compared |
| Your boat has hydraulic steering | A hydraulic pump drive instead of a linear drive | Best Hydraulic Autopilots in 2026: 10 Picks Compared |
| Your boat is a sailboat with mechanical steering | A sailboat pack named for the steering type | Best Sailboat Autopilots for 2026: 12 Picks Compared |
| You want a Raymarine linear drive and need the matching pack | Raymarine autopilot listings that name the drive type | Best Raymarine Autopilot (2026): Marine Autopilot Reviews |
| You are unsure which drive version your steering needs | Ask a dealer or check the maker's manual | Best Marine Autopilot (2026): Marine Autopilot Reviews |
Questions
What does stroke length mean on a linear drive?
It is the distance the drive rod travels from fully retracted to fully extended. That reach has to cover the full travel of your rudder or steering ram, plus the mounting geometry.
Is stroke length always stated on a listing?
No. Many listings name the drive type and model line but omit the stroke. When it is missing, ask the seller for the maker's data sheet or manual.
What happens if the stroke is too short?
The drive runs out of reach before the steering reaches full travel. The boat will not steer as far under the autopilot as the helm allows.
What happens if the stroke is too long?
The drive can push the rudder past its mechanical stop or strain the linkage. The stroke should match the rudder travel, not exceed it by a large margin.
Is stroke length the same as rudder travel?
No. Rudder travel is how far the rudder moves from one side to the other. Stroke is how far the drive rod moves. The linkage geometry connects the two.
Where can I find the stroke length for a drive?
On the maker's page for that drive unit, or in the maker's manual. If the listing does not state it, ask the seller before you order.
Recent updates
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