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

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

On a 40-50 foot sailboat, choosing an autopilot is rarely a brand decision. It’s a program decision: what you do with the boat dictates the algorithm, and the algorithm dictates the computer. The hardware follows. At this size, we’re 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’ve learned by regularly equipping both families over the past five years, on about sixty sailboats in this range. The goal isn’t to crown a winner: it’s to give you the decision grid we use in our engineering department. We distribute both brands. We state this honestly. It doesn’t prevent us from having clear preferences depending on the case.

Understanding autopilot architecture (the 3 minimum components)

Before comparing two ecosystems, you need to understand that autopilot is a catch-all term. An autopilot isn’t just one box. It’s at least 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, ground track), sensor data (compass, accelerometer, speed, wind transducer), and outputs the command to send to the ram. This is the component that contains the brand-specific algorithm. At B&G it’s the NAC-3 or NAC-2 depending on displacement and rudder type. At Raymarine it’s the Evolution unit (ACU, Autopilot Control Unit) offered in several versions based on ram power: 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’s through this that you engage the autopilot, switch from heading mode to wind mode, adjust gains, and 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 boat size, you almost always have at least two control heads: one near the helmsman, one at the nav station. 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 command from the computer and moves the rudder stock (via the quadrant or directly) or the tiller. On 40-50 foot boats, you’re almost exclusively using a hydraulic ram or electromechanical linear ram sized for the boat’s 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).

A ram that’s undersized is the primary cause of an autopilot that "zigzags" in beam seas. And it’s a recurring trap: we’ll cover this further down.

For more on rams, see our dedicated article: Bar ram for autopilot: how to choose, install, maintain. (complementary 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, Ultimes, 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 like Expedition. If you already have an H5000, the NAC-3 is almost always the logical next step. If you’re starting from scratch, it’s an investment justified for a performance-oriented program — including fast cruising.

Raymarine: the pragmatic path

Raymarine has a different philosophy: a broader public ecosystem, simpler 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 boats with hydraulic ram) is based on a 9-axis sensor (3-axis compass + 3-axis accelerometer + 3-axis gyro) integrated into the EV-1 unit, which radically simplifies installation.

This is the ecosystem you’ll find on most recent Beneteau, Jeanneau, Hanse boats straight from the yard. It 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 isn’t absurd, but it’s 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 recommend you validate with the distributor’s current price list — they fluctuate with tariff revisions.

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

See also: our autopilot range 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 read of the table

Three lines deserve comment:

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

Verdict by sailing program

Here’s 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’s better in absolute terms, but because:

• Installation is simpler (EV-1 condenses compass + IMU into a single unit),
• Native integration with Axiom MFDs is excellent, and most candidate boats are already equipped with Raymarine straight from the yard,
• The Auto / Track / Wind modes are perfectly suited to bluewater cruising that doesn’t require extreme tuning precision,
• 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, certain Ovni), the ram sizing must be taken very seriously regardless of the ecosystem.

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

B&G NAC-3 takes the lead if you plan to seriously exploit wind/heading/VMG functions. The granularity of tuning is better, the dialogue with a potential H5000 is native, and Expedition integration is seamless. For this type of program, the autopilot isn’t 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 also applies if you plan to keep the boat beyond a racing cycle and want an upgradeable platform.

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

It depends. Honestly.

• If operational reliability is the priority and the boat will pass through 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., catamaran charter), Raymarine dominates for operational reasons: changing 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 in 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 regularly correct, either in refit or in warranty service for the first installation.

1. Undersized ram

First trap, by far the most frequent. A 45-foot cruising sailboat with a Type 1 ram when it should be Type 2: it works in flat calm, but fails in beam seas. The computer’s algorithm can’t do anything about it — the motor doesn’t have the power to respond quickly to the command.

Field case (anonymized): Sun Odyssey 45.2, coastal program then decision for a 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 back 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 the average use. The price delta for the ram alone is around €400-700 VAT excluded. The safety delta is immeasurable.

2. Confusing electromechanical ram with 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 is more compact, hydraulic requires pump + circuit),
• acceptable noise in the aft cabin (hydraulic is quieter at steady state).

Field case: Hanse 458 equipped with an electric linear ram because that’s what the yard delivered. Program shifted to bluewater cruising with three rotating crew. After 18 months, clunking 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 settings

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

Field case: Bavaria 46, crew complaining that "the autopilot makes them sick" in 25 knots of breeze. Diagnosis: default "racing" gain profile applied while the program is comfortable cruising. Reset to a cruising profile, adjusted amplitude / counter-rudder. 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

An autopilot on a 40-50 foot sailboat, under load, draws several peak amps at the ram. An undersized power supply (cable cross-section too small, service battery aging, 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 cross-section, appropriate fuse, and a healthy battery bank are non-negotiable prerequisites. This is a natural opportunity to also review the boat’s overall energy balance (alternator, MPPT, hydrogenerator).

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

How to choose: the Skysat checklist

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

1. What is the dominant program? Coastal, offshore, charter, racing?
2. Length and displacement of the boat (not just the foot: a Pogo 12.50 and a Garcia 12 don’t require the same ram)?
3. Type of rudder: wheel (almost always on 40-50 foot boats), 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 yes, the NAC-3 becomes logical.
6. What routing software is planned (Adrena, Expedition, Squid, none)?
7. What is the total installed budget, distinguishing between hardware / ram / labor / sea trial commissioning?
8. Refit or new installation? On refit, the hidden cost is running new cables through existing runs. Hardware isn’t 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 flows between ecosystems without difficulty. But the native user interface remains that of the manufacturer: an Axiom MFD doesn’t engage a NAC-3 with the same ergonomics as a Zeus, and a p70s control head doesn’t natively pilot a NAC-3. For 90% of cases, it’s 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 boat like Allures, Garcia, Boréal, or certain Ovni, displacement and rudder stock dictate at least a Type 2 ram, preferably hydraulic for durability. The exact calculation is based on maximum torque at the rudder, not just length. This is a systematic engineering department point.

Is the H5000 system compatible with the NAC-3?

Yes, it’s 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 wind and speed data of higher quality 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 appropriate interface and a recheck of sizing. We do this on certain refits where the client wants to switch back to B&G but preserve the recent hydraulic system. It’s not a "plug and play" case: we always document compatibility on a case-by-case basis.

What’s 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 the upper segments with Type 2 and Type 3 hydraulic rams. On 40-50 foot boats, 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 do you need to be at stabilized cruising speed?

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

How much does a complete installation cost on a 45-foot sailboat in refit?

Ballpark figure, 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 trial commissioning). The range widens based 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 refit?

Three to five days in the workshop on average for a standalone autopilot installation, including half a day to a full day of sea trial commissioning. A refit that also includes switching to N2K, changing instruments, or a new MFD can stretch to two weeks.

Conclusion: a good autopilot starts with a good engineering study

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

If you’re preparing a specific project — refit or new build — we offer a customized pre-study that covers exactly this scope. You describe the boat and the program, and we send back an argued recommendation (hardware, ram, integration, total installed budget). No copy-paste quote: a real, signed file.

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

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

About the author

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

Wikidata: Q139564715