Key points in 30 seconds
- Choose a cockpit autopilot on laden displacement. Raymarine's limits: 3,000 kg (ST1000+), 4,500 kg (ST2000+), 6,000 kg (EV-100 Tiller), 7,500 kg (EV-100 Wheel).
- Loaded for cruising, a sailboat weighs roughly 20% more than its brochure displacement (Raymarine, B&G).
- Raymarine restricts the ST1000+ and ST2000+ to coastal sailing. Their thrust (57 and 77 kg) is far below that of the below-deck drives covered here (295 to 700 kg).
- Move to a below-deck autopilot as soon as laden displacement nears the limit, or as soon as your sailing includes nights at sea, big following seas or a short-handed crew.
- An undersized autopilot costs more than a correctly sized one: service returns, hours of hand steering, then buying the right pilot anyway.
Contents
A tiller pilot is a DIY install, stows in a locker and draws little current: Raymarine quotes 0.5 to 1.5 A in Auto mode for the ST1000+ and ST2000+. On a 30 to 38 ft sailboat it is often the first autopilot owners consider. The useful question is not “which brand?” but “how far?”: at what displacement, and for what kind of sailing, should a cockpit autopilot, tiller or wheel, give way to a below-deck system?
Published limits of cockpit autopilots
Raymarine publishes a maximum displacement for each cockpit autopilot and asks you to compare it with the fully laden figure, “often 20% above the designed displacement”. B&G gives the same warning for its drive units.
| Cockpit autopilot | Steering | Max. displacement | Thrust | Lock to lock |
|---|---|---|---|---|
| Raymarine ST1000+ | Tiller | 3,000 kg | 57 kg | 8 s |
| Raymarine ST2000+ | Tiller | 4,500 kg | 77 kg | 4.5 s |
| Raymarine EV-100 Tiller (A80737 cockpit tiller drive) | Tiller | 6,000 kg | Not stated | 4.0 s |
| Raymarine EV-100 Wheel | Wheel | 7,500 kg laden | Not stated | Depends on the steering |
The ST models are self-contained: compass, electronics and drive in a single 12 V unit, which Raymarine intends for coastal cruising, not offshore passage making. The EV-100 is a full Evolution system: EV-1 sensor core (the 9-axis heading sensor that also runs the steering logic), ACU-100 power unit (7 A continuous), SeaTalkng/NMEA 2000 networking. Its drive, however, stays in the cockpit. For wheel steering, Raymarine's Mk II wheel drive fits wheels with 3 to 8 spokes and steering systems with 1 to 3.5 turns lock to lock: check yours.
Thrust, helm speed and big seas
Thrust never tells the whole story. The ST2000+ applies its 77 kg 460 mm from the rudder stock axis (the mounting dimension in its handbook): roughly 350 N·m at the rudder, by our calculation. The Type 1, Raymarine's smallest linear drive, pushes 295 kg on a 250 mm tiller arm for 735 N·m of maximum rudder torque. So it delivers roughly twice the torque, not four times.
In a seaway, speed matters as much as force: 8 s lock to lock for the ST1000+, 4.5 s for the ST2000+, 4.0 s for the EV-100 tiller drive. When a following sea makes the boat round up, a slow pilot corrects late. The ST handbook sets its own conditions: limited heel, traveler eased to leeward, reef early, no dead run in strong winds and large seas (ideally at least 30° off), even headsail only in severe weather. After a sudden trim change the pilot can take up to a minute to settle back on course, so Raymarine asks for major course changes to be made by hand.
Chosen well, a cockpit pilot holds its course on a well-balanced boat. When the sea builds and the boat is loaded, margin is what runs out.
Decision grid: laden displacement and type of sailing
Start from the builder's light displacement and add crew, water, fuel, tender, provisions and gear, or the pilot makers' 20% if you cannot weigh the boat. Then match it to the most demanding sailing you plan, not the most frequent.
| Laden displacement | Tiller, coastal day sailing | Wheel, coastal day sailing | Nights at sea, big seas, short-handed |
|---|---|---|---|
| Up to 3,000 kg | ST1000+, or ST2000+ for margin | EV-100 Wheel | Below-deck pilot recommended |
| 3,000 to 4,500 kg | ST2000+; EV-100 near 4,500 kg | EV-100 Wheel | Below-deck pilot recommended |
| 4,500 to 6,000 kg | EV-100 Tiller | EV-100 Wheel | Below-deck pilot |
| 6,000 to 7,500 kg | Below-deck pilot: none of the tiller pilots covered here goes beyond 6,000 kg | EV-100 Wheel; below-deck pilot when close to 7,500 kg | Below-deck pilot |
| Over 7,500 kg | Below-deck pilot | Below-deck pilot | Below-deck pilot, with margin |
B&G's rule works for every brand. Between two pilot sizes, take the larger one: B&G warns that an undersized pilot may let you down exactly when you need it most.
Below-deck autopilots for 30 to 38 ft
A below-deck autopilot splits heading sensing, computing, power and drive. Bolted to the structure below deck, the drive pushes a tiller arm or the rudder quadrant: it is not a wheel pilot and never touches the wheel or the tiller. Raymarine requires steering that can be back-driven from the rudder; Garmin requires physical end stops, because the drive must never act as the stop.
| System | Below-deck drive | Maker's limit | Max. thrust, lock to lock | Worth knowing |
|---|---|---|---|---|
| Raymarine EV-200 Sail (EV-1, ACU-200) | Type 1 mechanical linear drive, 12 V, 300 mm stroke | 11,000 kg (10,000 kg in the 2016 installation instructions) | 295 kg peak; 11 s (±35°, no load) | ACU-200: 15 A continuous |
| B&G NAC-2 | T0 self-contained hydraulic ram, 12 V, 200 mm stroke | 9,000 kg; NAC-2 recommended up to 10 m (35 ft) | 350 kg; 12 s | NAC-2: 8 A continuous, 12 A peak |
| B&G NAC-3 | T1 self-contained hydraulic ram, 12 V, 250 mm stroke | 12,000 kg | 700 kg; 13 s | NAC-3: 30 A continuous, 50 A peak (1 s) |
| B&G NAC-3 | DD15 direct drive, drag link to a tiller arm or quadrant | 30 to 40 ft sailboats | 150 kg·m max. torque (about 1,470 N·m) | RF300 rudder feedback included |
| Garmin Reactor 40 Sail | SmartDrive, brushless mechanical linear drive with built-in ECU, 300 mm stroke | 45 ft and 15,000 kg | 181, 272 or 476 kg (software setting); 11 s | 10 to 32 V; 25 A peak; IPX7 |
These figures are ceilings, not targets: Garmin ships the SmartDrive on its medium force setting and asks you to use the lowest setting that steers reliably, to protect the steering system. Between these systems, the electronics already on board decide: see our B&G vs Raymarine guide.
What an undersized autopilot really costs
Compare two paths, not two purchase prices. The budget gap between a cockpit pilot and a below-deck system is significant; an undersized pilot claws it back in four ways.
- Service. The ST models have no user-serviceable parts: repairs go to an authorized Raymarine service agent. B&G recommends over-specifying the drive precisely to reduce wear and power consumption.
- Hand steering. A pilot at its limit gives up where it was needed: following seas, strong wind, night watches, a tired crew.
- Buying twice. The most expensive scenario: the cockpit pilot bought “to see how it goes”, then the below-deck system that was needed all along.
- Resale. A pilot used beyond its limits adds nothing to the boat; a correctly sized, documented below-deck system stands up to a survey.
The opposite mistake exists too: a badly installed linear drive can damage the hull, structure or steering, Raymarine warns. Sizing correctly means matching the drive to the boat and its steering, not buying the biggest one.
Limits and pitfalls
- Maximum thrust is a peak. Raymarine quotes peak thrust; Garmin calls the SmartDrive's 476 kg intermittent. And when two documents disagree, like the 11,000 and 10,000 kg quoted for the Type 1, size on the more cautious figure.
- Power supply. Below 10 V or while the engine is cranking, an ST can reset and change mode: Raymarine recommends a supply from a battery other than the engine-start battery. The SmartDrive should preferably be wired straight to the battery, through its 30 A fuse.
- Water and geometry. The SmartDrive goes below deck, away from any flooding or washdown, and must not tilt more than 5° at the ends of its stroke. Garmin strongly recommends professional installation.
- Maintenance. The working parts of the ST drives are sealed and lubricated for life. The SmartDrive needs greasing at least once a season, its leadscrew with AeroShell 64 only: any other grease can harden and seize the drive.
- Emergency release. A tiller pilot comes off by lifting its pushrod from the tiller pin. On the SmartDrive, pull the red-tagged R-pin at the tiller arm, never the base pivot pin.
Workshop verdict
- Tiller, up to 4,500 kg laden, coastal day sailing: ST2000+. The ST1000+ only below 3,000 kg, in sheltered waters.
- Tiller, 4,500 to 6,000 kg, coastal cruising: EV-100 Tiller. If your plans drift towards nights at sea, go straight to a below-deck system.
- Wheel up to 7,500 kg, coastal cruising: EV-100 Wheel, comfortably under the limit. Close to 7,500 kg, apply B&G's rule: size up, which means a below-deck drive.
- Nights at sea, singlehanded or short-handed: a below-deck pilot, whatever the displacement. Up to 35 ft and 9,000 kg, NAC-2 and T0; up to 10,000 kg, EV-200 and Type 1; beyond that or for margin, NAC-3 with T1 or DD15, or Reactor 40 with SmartDrive. Let your chartplotter pick the brand.
- Who a cockpit pilot is not for: the loaded cruising boat, the singlehander offshore, any sailing where the pilot steers more than the crew. Raymarine rules out offshore use for its ST models; we apply the same rule to every cockpit pilot.
A below-deck drive must be fixed to structure that can take its thrust; Raymarine and Garmin both recommend a professional installer. That is our workshop's job: survey, installation, commissioning.
Sources
- Raymarine product pages: ST1000+ and ST2000+, EV-100 Tiller, EV-100 Wheel, Mk II wheel drive, EV-200 Sail, Type 1 linear drive; guide Selecting your Raymarine drive unit.
- Raymarine documents: ST1000+/ST2000+ Tiller Pilots Owner's handbook, doc. 81130-8 (2021); Tiller drive autopilot Installation Instructions, doc. 87279-2 (2019); Linear Drive Installation Instructions, doc. 81175-7 (2016).
- B&G: T0 to T4 ram table, T0 ram, NAC-2, NAC-3, DD15; Simrad DD15 Direct Drive Installation Manual, doc. 20222303 rev. B (2017).
- Garmin: SmartDrive product page, SmartDrive actuator installation instructions, configuration guide, press release of 1 September 2026.
