Concept comparison
Hydraulic vs Linear Autopilot Drive
Compare hydraulic pumps and mechanical linear autopilot drives: steering compatibility, load, power, installation, service access and Australian budget scope.
- Option 1
- Hydraulic pump
- Option 2
- Mechanical linear drive
The drive is the part of an autopilot that does the work, and the choice is mostly made for you by the boat's steering. Hydraulically steered boats, which means most Australian power boats and many larger yachts, take a reversible pump plumbed into the steering circuit. Boats with a rudder stock you can reach and a mechanical wheel or tiller take a bolted to a .
Where you have a choice, on a yacht whose hydraulic steering is marginal or a heavy boat being refitted, the trade-offs are worth understanding, because they affect noise, power consumption and how the boat feels when you take the helm by hand.
Side by side
Hydraulic vs linear drive: specifications and installation
| Criterion | Hydraulic pump | Mechanical linear drive |
|---|---|---|
| Fits | Hydraulic steering: power boats, larger yachts, catamarans with hydraulic helms | A rudder stock with room for a tiller arm; mechanical wheel or tiller steering |
| How it steers | Pumps fluid into the existing steering cylinder | Pushes the tiller arm directly with a ram |
| Manual override | Wheel always works; pilot must be disengaged (or Shadow Drive) | Clutch disengages the ram; wheel or tiller free |
| Noise | Pump whine, audible in quiet cabins | Motor and gear noise, generally quieter |
| Power draw | Moderate; pump runs only while correcting | Moderate; continuous small corrections |
| Rudder feel by hand | Unchanged (hydraulic steering has no feel anyway) | Unchanged when clutch is released |
| Installation | Tee fittings, hoses, bleeding; rudder reference recommended | Tiller arm, foundation pad, rudder stops, rudder reference |
| Service | Fluid, seals, hoses | Lubrication, clutch, end stops |
| Redundancy | Steering circuit shared; a leak affects both | Independent of the main steering linkage |
Specifications and installation scope from manufacturer documentation. Any AUD prices shown are indicative; confirm current package contents and installed costs with a dealer.
Which should you choose?
Choose if
Which autopilot configuration suits your boat?
Choose Hydraulic pump if…
- The boat has hydraulic steering
- You want Shadow Drive or Safe Helm style override (Garmin, Furuno)
- There is no room for a tiller arm
Choose Mechanical linear drive if…
- The rudder stock is accessible below deck
- You want the quietest system and a mechanical clutch
- You sail a yacht with cable, rod or tiller steering
Begin with the steering survey
Identify how the wheel or tiller moves the rudder before choosing a drive. For a hydraulic proposal, provide cylinder identification and details of the existing circuit. For a mechanical linear proposal, establish the attachment point, movement and available space. Both require an assessment of the actual installation.
Ask the installer to explain why the proposed drive matches the steering arrangement. A boat with hydraulic helm steering does not make every pump suitable, and room beside a quadrant does not establish that a can be mounted correctly.
Compare access, maintenance and manual takeover
Review where hoses or linkages will run, what needs to be removed for service and how the drive is disengaged. Include the effect of a fault on manual steering in the handover. The answer depends on the installed circuit or mechanical arrangement, so request a boat-specific explanation.
Quotes should separate the drive from mounting, plumbing, electrical supply, feedback and commissioning. Ask which inspection tasks the owner can perform and which require a specialist. Keeping the final installation drawing and parts list makes later maintenance easier to scope.
Questions
Hydraulic vs linear drive: frequently asked questions
What size hydraulic pump do I need?
It is sized to the steering cylinder volume, not the boat's weight. Installers measure the cylinder and pick a pump that gives a sensible hard-over time, usually 10–15 seconds on a cruising boat and faster on a planing hull.
Can a linear drive be fitted to a boat with hydraulic steering?
Sometimes, if there is a tiller arm on the rudder stock and the hydraulic cylinder can be bypassed or backdriven. It is unusual and an installer should assess it.
Autopilot training after installation
The best pack badly understood is a worse autopilot than a modest one used well. A half-day handover covers modes, override, alarms and a failure drill.