The essentials in 30 seconds
- Your steering picks the drive, not the brand. Tiller: a tiller pilot, or a below-deck drive if the rudder stock is accessible. Wheel with wires and quadrant: a linear drive, a rotary drive or, on a small sailboat, a wheel drive. Hydraulic steering: a pump.
- Three families not to mix up. A linear drive pushes the rudder stock or the quadrant below deck, never the wheel. A rotary drive turns the steering gear through a chain and sprocket. A pump plugs into an existing hydraulic steering system.
- Size on fully laden displacement, up to 20% above design displacement according to B&G; between two sizes, take the larger. A pump is chosen by the volume of the steering cylinder.
- 2026 line-ups: of Raymarine, Navico (B&G, Simrad) and Garmin, only Raymarine offers a chain-driven rotary drive.
- Workshop verdict: rudder stock accessible, a linear drive on an independent tiller arm; otherwise, a rotary drive on overhauled steering gear; a wheel drive only for a small coastal sailboat of 7,500 kg or less.
Contents
Identify your steering
An autopilot drive is chosen in the lazarette, torch in hand, because it depends on how your helm moves the rudder: tiller, wheel linked to the quadrant by wires or cables, hydraulic steering (hoses run from the helm pump to the steering cylinder), and whether or not the rudder stock can be reached below deck.
Two-minute check. Autopilot disengaged, nobody at the wheel, hands clear of the steering wires: push the quadrant or tiller arm. If the wheel turns, the steering is back-drivable, a condition set in the Raymarine (linear drives), B&G (T1 and T2) and Simrad (DD15) manuals. If nothing moves, get a diagnosis before buying anything.
The table: steering × drive
Find the row for your steering; the "Acts on" column prevents most buying mistakes.
| Your steering | Suitable drive | Acts on | Examples, 2026 range | Ruled out |
|---|---|---|---|---|
| Tiller, light sailboat | Tiller pilot | The tiller, in the cockpit | Raymarine ST2000+ (4,500 kg), EV-100 Cockpit Tiller Drive (6,000 kg), Simrad TP32 (37 ft) | Rotary drive, pump, wheel drive |
| Wheel, wires or cables, quadrant | Linear drive, rotary drive, wheel drive (small sailboat) | The quadrant or a tiller arm; the steering gear, via chain and sprocket; the wheel | Raymarine linear and rotary drives, Mk II wheel drive; Garmin Class A and SmartDrive; B&G T0 to T2 | Pump: no hydraulic circuit to drive |
| Hydraulic steering | Reversing pump | The existing circuit, hence the steering cylinder | Raymarine and Navico pumps, Garmin SmartPump v2, Lecomble & Schmitt power units | Linear drives, rotary drive, DD15: specified for back-drivable mechanical steering |
| Rudder stock accessible below deck | Linear drive on an independent tiller arm, or direct drive | The rudder stock, via a tiller arm (a drag link for the DD15) | All linear drives; above 20 t, Raymarine Type 3 hydraulic, B&G T3, Garmin Class B; Navico DD15 | — |
A hydraulic ram is not a pump. An autopilot hydraulic ram (Raymarine Type 2 and Type 3 hydraulic linear drives, B&G T0 to T4, Garmin Class B, Lecomble & Schmitt linear sets) is a self-contained circuit that pushes the tiller arm of a mechanical steering system, just like an electromechanical linear drive. An autopilot pump has no ram of its own: it uses the cylinder of your hydraulic steering.
Linear, rotary, pump: what each one pushes
A linear drive acts on the rudder stock or quadrant
Mounted below deck, it pushes the tiller arm or quadrant and moves the rudder directly; wheel and wires follow. Raymarine recommends an independent tiller arm and asks you to consult the steering manufacturer before modifying a quadrant.
A rotary drive turns the steering gear
It couples to mechanical steering through a chain and sprocket. Raymarine specifies it for cable or rod steering and warns that a specific sprocket or a change to the chain may be needed. It works where the rudder stock is out of reach, but all its effort goes through the steering gear: slack cables or seized sheaves must be sorted before installation.
A pump plugs into hydraulic steering
A reversing pump connects to the steering lines and moves oil to the existing steering cylinder. It is chosen first by the volume of that cylinder.
Wheel drive and direct drive, two special cases
A wheel drive clamps to the wheel, with no work below deck; Raymarine limits its Cockpit Mk II Wheel Drive to sailboats of 7,500 kg or less (1 to 3.5 turns lock to lock). Navico's DD15 (motor, planetary gearbox, clutch) drives the tiller arm or quadrant through an output lever and drag link, or mounts in front of the pedestal.
What each manufacturer sells in 2026
- Raymarine: Type 1 and Type 2 electromechanical linear drives, Type 2 and Type 3 hydraulic linear drives, Type 1 and Type 2 rotary drives, Type 0.5 to Type 3 pumps, and the EV-100 cockpit units. There is no electromechanical Type 3: Raymarine's Type 3 linear drive is hydraulic only.
- Navico (B&G, Simrad): T0 to T2 all-in-one hydraulic rams, T3 with a separate pump, T4; the DD15; the SD10, a cable drive for 25 to 37 ft sailboats (the previous version is discontinued); PUMP and RPU pumps. No chain-driven rotary drive and no wheel drive.
- Garmin: for mechanical steering, linear drives only (the electromechanical Class A, the hydraulic Class B Compact v2 and Class B, and the brushless SmartDrive announced on 1 September 2026); for hydraulic steering, pumps including the SmartPump v2.
- Lecomble & Schmitt: hydraulic linear sets (ram plus separate reversing power unit), and RV1 and RV2 autopilot power units for double-rod cylinders.
Sizing: laden displacement and manufacturer charts
Weigh the boat ready to sail: tanks full, provisioned, equipped. B&G says a boat in that state can be up to 20% heavier than its design displacement, recommends the larger model when you fall between two, and warns that an under-rated pilot may not cope when you need it most.
Lecomble & Schmitt and the B&G T1/T2 manual also work in rudder torque (kg·m; 1 kg·m ≈ 9.81 N·m). Torque = thrust × tiller arm radius: the 295 kg of Raymarine's Type 1 on a 250 mm arm gives about 720 N·m, consistent with the 735 N·m in its manual.
Drive unit charts
| Model | Family | Published max displacement | Max thrust | Stroke |
|---|---|---|---|---|
| Raymarine Type 1 (M81130) | Electromechanical | 10,000 kg (2023 manual), 11,000 kg (product page) | 295 kg | 300 mm |
| Raymarine Type 2 short / long | Electromechanical | 15,000 / 20,000 kg | 480 kg | 300 / 400 mm |
| Raymarine Type 3 hydraulic | Hydraulic (pump, reservoir, ram) | 35,000 kg | see manual | see manual |
| Raymarine rotary Type 1 / Type 2 | Chain-driven rotary | 11,000 / 20,000 kg | — | — |
| Garmin Class A (010-11572-00) | Electromechanical | 12,927 kg | 400 kg | 303 mm |
| Garmin SmartDrive | Brushless electromechanical | 15,000 kg | 181, 272 or 476 kg (setting) | 300 mm |
| Garmin Class B Compact v2 (010-12029-01) | Integrated hydraulic | 48,400 lb, about 22 t | 730 kg | 254 mm |
| Garmin Class B (010-11573-00) | Hydraulic | 79,000 lb, about 35.8 t | 1,080 kg | 303 mm |
| B&G T1, T2 | Integrated hydraulic | not published, sized by torque | 700 kg (intermittent) | 255 mm |
| B&G T3 | Hydraulic, separate pump | 36,000 kg | 1,100 kg | 300 mm |
| Navico DD15 | Direct drive | 30 to 40 ft sailboats | 150 kg·m torque | — |
| Lecomble & Schmitt 50 ST 20 | Hydraulic, separate power unit | under 60 ft and 200 kg·m | 700 kg | — |
Pumps: the steering cylinder volume decides
The volume is in your steering system's documentation or on the cylinder itself. Raymarine asks for the pump whose range covers that volume, without going up or down a size, and for the volumes of two cylinders in parallel to be added together.
| Pump | Steering cylinder volume |
|---|---|
| Raymarine Type 0.5, Type 1, Type 2, Type 3 | 50–110, 80–230, 230–350, 350–500 cc; above that, a constant-running pump up to 1,200 cc |
| Navico PUMP-2, PUMP-3, PUMP-4 | 80–250, 160–550, 290–960 cc |
| Garmin SmartPump v2 | 4–24 cu in, about 66–393 cc, configurable flow |
| Lecomble & Schmitt RV1, RV2 | up to 216 and 432 cc, adjustable flow |
Limits and pitfalls
- Rudder stops. Garmin spells it out: without physical end stops, the drive becomes the stop and gets damaged.
- Tiller arm and quadrant. They take the drive's peak thrust, up to 480 kg on Raymarine's electromechanical linear drives, whose manual sets the arm radius (250 mm, 355 mm for the Type 2 long), a drive at 90° to the arm with the rudder amidships, and no more than 5° of misalignment.
- Figures that don't match. Raymarine's Type 1 is rated at 10,000 kg in its September 2023 manual and 11,000 kg on its product page: go with the lower figure. Garmin France calls the Class A the "type 1 linear drive" and the Class B the "type 2 linear drive"; the Class B Compact v2 has no type number, and the "Type 3" some dealers mention does not exist at Garmin: go by the class (A, B Compact v2, B) and the manufacturer part number.
Workshop verdict
Tiller-steered sailboat, coastal sailing: a tiller pilot, the ST2000+ up to 4.5 t or the Cockpit Tiller Drive up to 6 t. Beyond that, or offshore (Raymarine does not intend its ST1000+ and ST2000+ for offshore passage making), a below-deck drive if the rudder stock is accessible.
Wheel-steered sailboat of 9 to 15 t, rudder stock accessible: a linear drive on an independent tiller arm, such as Raymarine's Type 1 (10 t) or Type 2 short, Garmin Class A or SmartDrive, or B&G T1 or T2 for an all-in-one hydraulic unit. It acts on the rudder without going through the wires; B&G notes that its rams can help steer if the steering gear fails.
Same boat, rudder stock out of reach: a Raymarine rotary drive, Type 1 up to 11 t or Type 2 up to 20 t, on overhauled steering gear.
Small wheel-steered sailboat, coastal, no work possible below deck: the Mk II wheel drive, within its 7,500 kg limit.
Hydraulic steering: the pump whose range covers your cylinder volume; from 4 to 24 cu in, a single Garmin model covers it all, the SmartPump v2, with configurable flow.
Over 20 t with mechanical steering: a hydraulic linear drive, Raymarine Type 3, B&G T3, Garmin Class B, or a Lecomble & Schmitt set chosen by rudder torque.
The DD15 is made to order: its manual asks you to specify the drag link and, if needed, the tiller arm. For a steering survey and sizing before a quote: survey, installation and commissioning at the Skysat workshop.
Sources
- Raymarine: Autopilot Drive Units range, product pages Type 1 Linear, Type 2 Linear, Type 3 Hydraulic Linear, Type 1 Rotary, Cockpit Mk II Wheel Drive, ST1000+ and ST2000+; guides to drive units and hydraulic pumps; Linear Drive installation instructions 81175-8-EN (09-2023).
- B&G: Autopilot Drive Units, product pages T0, T3, DD15, SD10; RAM T1 and T2 manual.
- Simrad: Drive Units, product pages PUMP-3 and TP32; DD15 manual.
- Garmin: product pages Class A, Class B Compact v2, Class B, SmartDrive, Reactor 40 Hydraulic with SmartPump v2, Reactor 40 Mechanical; Class A installation instructions.
- Lecomble & Schmitt: choosing a linear set, product pages 50 ST 20 NEWAVE, RV1, RV2.
