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A hybrid system that isn't intended to replace the outboard motor
The joint announcement by Mercury Marine and BlueNav, made on the eve of the 2026 Cannes Yachting Festival, is particularly noteworthy for the technical architecture it employs. The two companies are not attempting to replace the internal-combustion outboard engine with an electric motor. Instead, they propose integrating two independent propulsion systems, each reserved for the applications where it is most effective.
The boat chosen for the demonstration is a Highfield Patrol 700. This 7-meter RIB is powered by a 250-horsepower Mercury SeaPro as its main propulsion system, supplemented by two 8-kW BlueNav electric motors.
The difference in power immediately provides the key to understanding the system. With a combined electric output of 16 kW compared to a 250-horsepower outboard, the two modes are not intended to be interchangeable. The Mercury remains the go-to option for situations requiring speed and power. The electric motor kicks in when the need shifts to low speed, precision, and quiet operation.
It is therefore necessary to clarify what is meant here by the term ?hybrid boat propulsion.? According to the information provided, this does not refer to a common powertrain in which an internal combustion engine and an electric motor drive the same propeller. The BlueNav units serve as auxiliary propulsion systems. They are retractable and can therefore be raised out of the water when not in use.
This separation may seem less sophisticated than fully integrated hybridization. Yet it is at the heart of the concept: it makes it possible to consider electrifying a boat that already has its own main propulsion system.
The refit opens up a much wider range of boats
For a boat owner, the issue then becomes a reality. Switching to electric power does not necessarily mean removing an internal combustion engine that is still in working order. BlueNav markets its systems as suitable for both new boats and refits. The concept involves adding electric propulsion, batteries, power electronics, and controls to the existing system.
This approach avoids the rather drastic choice between keeping one?s combustion-engine boat or replacing the entire propulsion system. It also allows the boat to retain the range provided by fuel for voyages where an all-battery-powered electric propulsion system would require a significant amount of energy. The Highfield is an interesting demonstration model in this regard. With a length of approximately 7 meters and a maximum rated power of 250 chevaux according to the manufacturer?s specifications, it belongs to a category in which the internal-combustion outboard motor delivers significantly more power than the two BlueNav units.
But simplicity in principle does not mean there are no installation constraints. Two additional engines must be fitted on board. The batteries, electronics, and wiring must also be accommodated, while maintaining proper weight distribution. However, we do not yet have any information on the capacity of the batteries installed on the Highfield, their weight, or the total mass of the added system. This data will be essential for assessing the actual effectiveness of the refit. On a 7-meter RIB, an additional few dozen or a few hundred kilograms is never entirely insignificant.
Electric vehicles really come into their own at low speeds
The proposal becomes more convincing when we consider the intended uses of electric motors. An 8-kW motor is obviously not designed to match the performance of a 250-ch outboard. But maximum power isn?t the main criterion when it comes to gently moving the boat or adjusting its position.
BlueNav announces a thrust of 110 kgf for its 8 kW Outboard. Since the demonstration boat is equipped with two of them, the system features two thrusters that can be controlled to adjust the RIB?s course and positioning. The appeal, therefore, lies not only in electric propulsion but also in the use of these motors as actuators for maneuvering aids.
In particular, BlueNav is developing a Virtual Anchor feature. Based on the GPS position, the engines automatically make the necessary adjustments to counteract the wind and current. The principle is similar to dynamic positioning: the boat uses its propulsion to remain within a specific area rather than relying on a physical anchor.
Other features are available, including position and orientation hold, course or route hold, and 360° docking. The latter uses thrust vectoring to facilitate tight maneuvers. In this context, electric propulsion is no longer viewed solely as a way to travel miles without gasoline. It is also becoming a maneuvering tool.
Silence, maneuvers, and positioning rather than speed
The complementary nature of the two propulsion systems also helps avoid one of the classic challenges of electrifying high-speed boats: energy consumption increases sharply as soon as the power demand becomes significant. The system presented by Mercury and BlueNav circumvents the problem rather than solving it. High-speed travel is still powered by gasoline. The batteries are reserved for times when the boat requires much less power. This division of labor can be beneficial for approaching the dock, certain fishing activities, waiting, or port maneuvers. It also makes an immediately noticeable difference on board: when the internal combustion engine is turned off, its noise and much of its vibration disappear.
However, caution is warranted regarding the announced use in ?protected areas.? Electric propulsion alone obviously does not grant the right to navigate in a restricted area. The rules governing access, speed, anchoring, and navigation remain those applicable locally. The same caution applies to the fuel savings highlighted by the two partners. The principle makes sense: every period during which the outboard motor is turned off saves the fuel it would have consumed. However, no comparative data has been provided for the Highfield.
It is therefore impossible at this stage to announce a credible fuel-efficiency figure. It will all depend on the boat?s usage profile. A boat that spends a lot of time holding position or traveling at low speeds will not achieve the same results as a RIB used primarily to cover long distances quickly.
The 115-amp alternator tells only part of the story
Mercury places particular emphasis on the electrical capabilities of its outboard motors. Some of the brand?s V6 and V8 engines can indeed be equipped with an alternator rated up to 115 A?either as standard equipment depending on the model or via a kit that replaces an 85 A alternator. This capacity is particularly useful on boats with an increasing number of electrical loads: navigation electronics, depth sounders, audio systems, pumps, or other equipment such as bow thrusters. In the case of a hybrid system, however, this raises an additional question: can we use the hours the internal combustion engine is running to replenish the energy consumed by the electric system?
The press release clearly links the Mercury?s electricity generation capacity to charging the BlueNav system. However, it does not provide enough detail about the installation to determine its energy balance. An alternator rated at 115 A does not necessarily supply 115 A continuously to the propulsion batteries. Its output varies significantly with engine speed, while the engine and the boat?s equipment themselves draw a portion of the available current. There is also the issue of voltage. BlueNav states that it uses a 48-volt propulsion system. This requires an appropriate power management system between the outboard motor?s circuit and the propulsion batteries.
Without knowing the onboard energy capacity, the power actually available for recharging, and the efficiency of that conversion, it is impossible to accurately calculate how much time of thermal operation would be needed to recover one hour of electric use. And that is probably one of the most interesting metrics to measure during a real-world test.
The Cannes trials should provide the missing figures
Mercury Marine and BlueNav plan to take their Highfield Patrol 700 out for test runs during the Cannes Yachting Festival, scheduled for September 8?13, 2026. The purpose of these test runs will not be limited to verifying that a RIB can maneuver quietly using its electric motors. That principle has already been established. The truly informative data will instead focus on the speed achieved under electric propulsion, the instantaneous power consumption of the two motors, the range in different modes, and the system?s ability to maintain its position when the wind picks up.
We will also need to observe the transitions between the two modes. How long does it take to deploy the thrusters? How do they respond in short, choppy waves? How much space does the system take up at the stern? And what impact does it have on the boat's load?
Weight and cost will be just as critical. In September 2026, BlueNav will offer its 8 kW Outboard with Smart Navigation starting at 13,950 euros (excluding tax) in a basic configuration, not including installation, batteries, or shipping. The prototype uses two of them... This list price therefore does not allow for an estimate of the cost of the complete system installed on the Highfield, but it serves as a reminder that hybridization involves significant equipment and is not merely an electrical accessory. How many hours at sea would it take to recoup the cost of an installation priced at over ?30,000?
Another Approach to Hybridizing Motorboats
The Mercury-BlueNav partnership does not address the issue of electrifying high-speed boats. Instead, it takes a different approach: retaining the operational efficiency of the internal combustion engine for power-intensive phases and shifting to electric power for applications that can operate with much less. For existing vessels, this additional architecture has a clear advantage: it does not render the existing propulsion system obsolete. It also allows electric motors to be used for positioning and maneuvering functions that go beyond the mere issue of fuel economy.
A comprehensive assessment is still needed. Range, charging, added weight, actual fuel savings, and installation costs will play a greater role in determining the value of this hybrid powertrain than simply adding a 250 ch internal combustion engine and two 8 kW electric motors.
The sea trials of the Highfield in Cannes will provide the first opportunity to compare the concept with the actual performance of a boat. To assess the effectiveness of this hybrid system, we?ll need to break out the calculator along with the electric motors.
