B&G vs Raymarine autopilot for 40-50 foot sailboat: 2026 technical guide

By Paul-Louis Defrétière, president of Skysat. Article based on installations conducted by our engineering department between 2021 and 2026.

On a 40-50 foot sailboat, choosing an autopilot is rarely a brand choice. It is a program choice: what you do with the boat dictates the algorithm, and the algorithm dictates the computer. The hardware follows. At this size, we are in the segment where both ecosystems — B&G NAC-3 and Raymarine Evolution — are perfectly credible. Neither is ridiculous. Neither is universally better.

This article summarizes what we have learned by regularly equipping both families over five years, on about sixty sailboats in this range. The goal is not to crown a winner: it is to give you the decision grid we use in our engineering department. We distribute both brands. We state this honestly. It does not prevent us from having clear preferences depending on the case.

Understanding autopilot architecture (the 3 minimum components)

Before comparing two ecosystems, you must understand that autopilot is a catch-all term. An autopilot is not a single box. It is at minimum three distinct components that communicate.

1. The computer (computer / CPU)

This is the brain. It receives as input the helmsman's command (heading, wind angle, course over ground), sensor data (compass, accelerometer, speed, wind transducer), and outputs the command to send to the ram. This is the element that contains the brand-specific algorithm. At B&G it is the NAC-3 or NAC-2 depending on displacement and rudder class. At Raymarine it is the Evolution box (ACU, Autopilot Control Unit) available in several versions depending on the ram power to be controlled: EV-100, EV-200, EV-300, EV-400.

This is also the component that contains — or connects to — the inertial measurement unit. The quality of the compass + IMU directly determines the quality of the control loop, especially in rough seas.

2. The control head (display)

This is the user interface. It is through this that you engage the autopilot, switch from heading mode to wind mode, adjust gains, read rudder angle. At B&G: Triton 2 Pilot, Zeus Touch (integrated in the MFD), H5000 Graphic Display. At Raymarine: p70s or p70Rs, Axiom (integrated in the MFD), i70s for readout.

At this size of sailboat, you almost always have at least two control heads: one near the helmsman, one at the chart table. This is a real ergonomics issue we address in the pre-project phase.

3. The ram (drive unit / linear ram)

This is the muscle. It receives the order from the computer and moves the rudder stock (via the quadrant or directly) or the tiller. On 40-50 foot sailboats, we are almost exclusively on hydraulic or electromechanical linear rams sized for the boat class (Type 1, Type 2, Type 3 at Raymarine; equivalent classes at Lecomble & Schmitt on the B&G side, which is a major OEM supplier in this segment).

An undersized ram is the leading cause of an autopilot "zigzagging" in beam seas. And it is a recurring trap: we address this further down.

For more on rams, see our dedicated guide: Rudder ram for autopilot: how to choose, install, and maintain. (additional article)

Ecosystems: B&G NAC-3 and Raymarine Evolution

B&G: racing heritage

B&G has a clear history — offshore racing. The brand has historically equipped IMOCA, Class40, Ultim, and most high-end performance cruising sailboats for twenty years. The NAC-3 is the direct evolution of an ACP lineage started at B&G in the 1990s and refined with every Olympic cycle and every Vendée Globe.

Its philosophy: fine control loop, deep integration with the H5000 system (which produces extremely precise wind/speed/performance data), and strong compatibility with professional routing software such as Expedition. If you already have an H5000, the NAC-3 is almost always the logical next step. If you are starting from scratch, it is an investment that makes sense for a performance-oriented program — including fast cruising.

Raymarine: the pragmatic path

Raymarine has a different philosophy: an ecosystem more accessible to the public, easier to implement, better supported internationally, natively integrated into Axiom MFDs with a renowned touchscreen interface. The Evolution Pro range (with ACU EV-400 typically on 40-50 foot sailboats with hydraulic ram) is based on a 9-axis sensor (3-axis compass + 3-axis accelerometer + 3-axis gyroscope) integrated into the EV-1 box, which radically simplifies installation.

This is the ecosystem found on most recent Beneteau, Jeanneau, and Hanse sailboats straight from the builder. This matters: if your 40-50 foot sailboat is a Sun Odyssey 410, an Oceanis 461, or a Hanse 458, you probably already have Raymarine wired. Reconfiguring everything to B&G is not absurd, but it is not cost-neutral.

Technical comparison: B&G NAC-3 vs Raymarine Evolution

The table below summarizes the main differences we use in our engineering department. Figures marked with an asterisk are those I prefer you validate with the distributor list price on the day you request a quote — they change with each price revision.

*Indicative 2026 figures excluding labor, excluding specific wiring, excluding redundant rudder sensor. Ranges vary depending on final configuration and current distributor list price.

See also: our autopilots in stock. And for product pages, the B&G NAC-3 (TODO link to exact product page) and the Raymarine Evolution (TODO link to exact product page).

Quick reading of the table

Three lines deserve comment:

• Compass / IMU: the major difference in approach. B&G separates the autopilot from the compass, which allows using a top-tier system (Hercules on H5000) while sharing data with the instruments. Raymarine integrates everything in the EV-1, which is simpler to install but makes the compass dedicated to the autopilot.
• Sailing routing: if you sail with Expedition, the H5000 is the natural partner. If you use Adrena for amateur racing, both ecosystems work honestly, with a slight advantage for B&G via H5000.
• Customization: the NAC-3 exposes more low-level parameters to advanced users. This is an asset in racing/regattas, but also a trap in cruising (see common errors below).

Verdict by sailing program

Here is how we guide clients in the pre-study phase.

Comfortable bluewater cruising (family transatlantic, Mediterranean + Atlantic program)

Raymarine Evolution Pro (EV-400) will, in the majority of cases, be the right choice. Not because it is better in absolute terms, but because:

• Installation is simpler (EV-1 condenses compass + IMU in a single box),
• Native integration with Axiom MFDs is excellent, and most candidate boats are already equipped with Raymarine straight from the builder,
• The Auto / Track / Wind pilot modes are perfectly suited to bluewater cruising that does not require extreme fine-tuning,
• The total installed cost is generally 10-15% lower than the equivalent B&G configuration, because you capitalize on the existing Raymarine ecosystem.

Exception: if the boat has a heavy rudder stock (Garcia, Allures, Boréal, some Ovni), the ram oversizing must be taken very seriously regardless of the ecosystem.

Amateur / club racing (IRC or ORC weekend regattas, fast cruising)

B&G NAC-3 takes the lead if you plan to seriously exploit wind/heading/VMG functions. The granularity of adjustment is better, the dialogue with a potential H5000 is native, and the integration with Expedition is seamless. For this type of program, the autopilot is not just "holding course": it becomes a third crew member that steers better than you upwind, and you need to be able to give it the right parameters.

This is also the case if you plan to keep the boat beyond one racing cycle and want an upgradeable platform.

Semi-pro bluewater cruising (world cruise, charter program, rental)

It depends. Honestly.

• If operational reliability is paramount and the boat will sail in areas where Raymarine dealers outnumber B&G dealers (Pacific, Caribbean), Raymarine is more defensible. Spare parts matter as much as performance.
• If the program includes sporty passages like Cape Verde / Brazil / direct route, and a skipper who knows how to tune an autopilot, B&G retains a technical advantage in difficult conditions.
• If the boat is destined for large-scale charter (e.g., charter catamaran), Raymarine dominates for operational reasons: rotating crews, international support, ease of use.

In all cases, a bluewater program deserves a proper engineering pre-study: this is exactly the situation where one hour of pre-study avoids several thousand euros of post-installation fixes. See our technical studies and 3D design service.

Common field errors seen on +60 Skysat installations

Here are the real traps we correct regularly, either in refits or in warranty service after the first installation.

1. Undersized ram

Top trap, by far the most frequent. A 45 foot cruising sailboat with a Type 1 ram when it should have a Type 2: it works in flat calm, but it falls apart in beam seas. The computer's algorithm cannot fix this; the motor lacks the force to respond quickly to the command.

Field case (anonymized): Sun Odyssey 45.2, coastal program then decision for transatlantic. The autopilot had been sized for calm coastal use. First rough seas in the Bay of Biscay: autopilot in safety mode after a few minutes, helmsman at the wheel for 36 hours. Refitted with a higher-class ram and redundant rudder sensor. Autopilot perfectly operational on the next transatlantic, with no safety triggers.

Skysat rule: we always size for the most demanding program anticipated, not for average use. The price delta for the ram alone is around €400-700 ex-works. The safety delta is immeasurable.

2. Confusion between electromechanical and hydraulic ram

On a 40-50 foot sailboat, the choice between an electric linear ram and a hydraulic one is essentially based on:

• Frequency of use (charter / liveaboard pushes toward hydraulic for durability),
• Available space (electric linear more compact, hydraulic requires pump + circuit),
• Acceptable noise in the aft cabin (hydraulic quieter at steady state).

Field case: Hanse 458 equipped with an electric linear ram because that is what the builder delivered. Program shifted to bluewater cruising with three rotating crew. After 18 months, clunks and mechanical play noticeable. Converted to hydraulic: noise gone, nominal durability restored. The electric linear would have been perfect for weekend use.

3. Incorrect gain setting

The autopilot doesn't work, you call the installer, and the issue is not hardware: it is the gains that are wrong. On B&G NAC-3 in particular, the richness of exposed parameters can lead to an autopilot "over-reacting" in rough seas if profiles have never been fine-tuned beyond the initial setup.

Field case: Bavaria 46, crew complaining that "the autopilot makes them sick" at 25 knots. Diagnosis: default "racing" gain profile applied while the program is comfortable cruising. Reset to cruising profile, adjusted amplitude/counter-helm. No more complaints.

Skysat advice: commissioning must include a sea trial in representative conditions, not just a dockside setup. This is included in our standard services.

4. Insufficient power supply

A 40-50 foot sailboat autopilot, under load, draws several peak amps at the ram. An undersized power supply (cable cross-section too small, service battery degraded, fuse at the limit) causes voltage drops on load peaks, and the computer switches to degraded mode without a clear message. You suspect the autopilot; the culprit is the electrical distribution.

Advice: dedicated cable with appropriate cross-section, properly sized fuse, and a healthy battery bank are non-negotiable prerequisites. This is also a natural opportunity to review the boat's overall energy balance (alternator, MPPT, hydrogenerator).

Upcoming additional article: How to size your lithium battery bank for bluewater cruising (article 10 of our series)

How to choose: the Skysat checklist

Before ordering, these 8 questions clarify the choice 90% of the time.

1. What is the dominant program? Coastal, bluewater, charter, racing?
2. Length and displacement of the sailboat (not just the LOA: a Pogo 12.50 and a Garcia 12 do not require the same ram)?
3. Type of rudder: wheel (almost always on 40-50 foot sailboats), tiller (exceptional)?
4. What existing electronics ecosystem is on board? If Raymarine is already wired everywhere, switching to B&G is rarely justified.
5. Is there already an H5000 or equivalent system? If so, the NAC-3 becomes logical.
6. What routing software is envisaged (Adrena, Expedition, Squid, none)?
7. What is the total installed budget, distinguishing between hardware / ram / labor / sea commissioning?
8. Refit or new installation? On refit, the hidden cost is pulling new cables through existing runs. Hardware is not everything.

From these answers, we produce a priced recommendation within 3-5 days in our engineering department. See our technical studies and our installations.

FAQ

Can you integrate a B&G autopilot into a Raymarine network, and vice versa?

Yes for basic data, via NMEA 2000 — the shared standard bus. GPS position, speed, wind, heading: this circulates between ecosystems without difficulty. But the native user interface remains that of the manufacturer: an Axiom MFD does not engage a NAC-3 with the same ergonomics as a Zeus, and a p70s control head does not natively pilot a NAC-3. For 90% of cases, it is better to stay consistent within one ecosystem for the autopilot chain.

Which ram to choose for a 45 foot aluminum sailboat?

On a 45 foot aluminum sailboat like Allures, Garcia, Boréal, displacement and rudder stock dictate a Type 2 ram as a minimum, preferably hydraulic for durability. The exact calculation is based on maximum torque at the rudder stock, not just length. This is a systematic engineering department point.

Is the H5000 system compatible with the NAC-3?

Yes, it is even the reference combination on the B&G side. The H5000 (CPU and Hercules) communicates with the NAC-3 over the FastNet/N2K bus, and provides the autopilot computer with higher-quality wind and speed data than an entry-level system. This is the structural argument for a performance-oriented program.

Is the NAC-3 compatible with existing Raymarine rams?

Yes, via an adapter interface and a recheck of sizing. We do this on some refits where the client wants to switch back to B&G but preserve the recent hydraulic system. This is not a "plug and play" case: we always document compatibility on a case-by-case basis.

What is the difference between EV-200, EV-300, and EV-400 at Raymarine?

These references correspond to ram power classes: EV-200 for mid-sized boats (up to ~13 meters in practice), EV-300 and EV-400 for larger segments with Type 2 and Type 3 hydraulic rams. On 40-50 foot sailboats, the EV-400 is the dominant reference with a hydraulic ram. The computer changes with the class (ACU-200 / ACU-300 / ACU-400).

Can you engage the autopilot as soon as the engine is running, or must you wait for stabilized speed?

Technically yes, but at very low speed the autopilot struggles to correct because there is little rudder effect. Beyond ~2 knots forward, engagement is reliable. In harbor manoeuvres, always disengage.

What is the cost of a complete installation on a 45 foot sailboat in a refit?

Rule of thumb, excluding specific complications: between €8,000 and €14,000 VAT included for a complete kit (computer + control head + new ram + rudder sensor + wiring + labor + sea commissioning). The range widens depending on ram configuration, cable runs, and integration with the rest of the electronics. A personalized quote is essential. See our installations for priced examples.

How long does an autopilot installation take in a refit?

Three to five days in the workshop on average for an autopilot installation alone, including half a day to one day of sea commissioning. A refit that also includes conversion to N2K, a change of instruments, or a new MFD can take up to two weeks.

Conclusion: a good autopilot starts with a good engineering file

On 40-50 foot sailboats, B&G and Raymarine are equivalent when correctly sized. What distinguishes an installation that lasts ten years from one that ends up in warranty service is rarely the brand: it is the quality of the engineering file, the correct sizing of the ram, the consistency with the onboard electronics ecosystem, and the real sea commissioning.

If you are preparing a specific project — refit or new build — we offer a personalized pre-study that covers exactly this scope. You describe the boat and the program, we return a reasoned recommendation (hardware, ram, integration, total installed budget). No copy-pasted quote: a real file, signed.

Request an autopilot pre-study — Skysat engineering department, Carnac.

Skysat distributes B&G, Raymarine, Simrad, Lowrance, Garmin, Furuno, among others. This article reflects our view as an installer and engineering department: it is neither sponsored nor biased to push one brand over another.

About the author

Paul-Louis Defrétière is president of Skysat and an engineer in mechatronic systems. Fifteen years in high-level competitive sailing, including stints with Oracle Team USA and American Magic. R&D autopilot engineer for IMOCA Safran 2. See his author page for the full list of articles he has authored.

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