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A 6.7 m hybrid boat equipped with a thermal outboard and retractable electric pods is still a rare sight on European waters. Yet this is the choice made by Marius Hondema for his Aluship 670. The aim of the Amsterdam test was to observe on the water what the BlueNav system, a combination of electric propulsion, 3D joystick and assisted navigation functions, can really do.
Hybrid architecture designed for small boats
The main propulsion system on this Aluship 670 is a 100-hp Honda outboard. A classic combustion engine, used for fast travel and transit. But thermal propulsion is not allowed on Amsterdam's canals. And the maximum speed in the Dutch capital is 6 km/h. So an alternative solution had to be found.
That's why two 8 kW BlueSpin electric pods are located under the hull. They are installed on retractable supports. When raised, they create no drag under the hull, thus avoiding efficiency losses when the boat is powered by an internal combustion engine.
This hybrid architecture offers two advantages:
- The first is propulsion redundancy. Electric pods can be used as main propulsion, but also as back-up in the event of failure of the main engine.
- The second is maneuverability. Thanks to two independent thrusters, the boat can move sideways or pivot on the spot, an obvious advantage in narrow canals like those of Amsterdam.
The whole system is controlled by a 3D joystick linked to the BlueNav system.
A joystick to move the boat in all directions
On the water, the first impression is of precise steering. The joystick centralizes management of the two electric pods, giving direct control of thrust. By pushing the joystick to one side, the boat moves sideways. A function known as lateral docking.
In narrow canals lined with barges and pontoons, this function comes into its own. The boat can glide towards a quay without having to simultaneously operate the main engine and the rudder.
The system also allows complete rotation of the boat on its axis. The two pods work in opposition to each other to rotate the hull. In some passages in the center of Amsterdam, where the available width is no more than a few meters, this on-the-spot rotation greatly simplifies U-turns.
Handling remains fairly intuitive. After just a few minutes, Marius Hondema can handle the boat with a precision akin to that of a harbor thruster.
While joystick control has become the norm on high-powered thermals, its smoothness and precision are unrivalled here.
Course keeping and drift correction in current
Beyond maneuvering, BlueNav integrates several navigation assistance functions.
The Heading Hold function maintains a precise course. The system automatically corrects deviations caused by wind or current. On the canals of Amsterdam, where the effects of currents appear near locks or movable bridges, this assistance stabilizes the trajectory.
Another interesting function is Drift Lock. This system keeps the boat's drift under control. Speed and drift angle remain constant despite external disturbances. In a river or port area, this function makes it easier to wait in front of a bridge or lock, for example.
The virtual anchor and position keeping
One of the system's most spectacular features is the virtual anchor. BlueNav calls it DPS, for Dynamic Positioning System.
The principle is based on GPS and the automatic piloting of electric pods. Once the function is activated, the boat remains positioned on a precise point. The pods constantly adjust their thrust to compensate for wind or current. The boat thus remains stationary without dropping anchor.
In an urban environment like Amsterdam, this function can be used to wait for a bridge to open, or to keep the boat in front of a quay while preparing a maneuver.
And on a more open stretch of water or at sea, it can also be used for certain activities such as fishing, or to remain stationary in an area where anchoring is prohibited.
Automatic navigation and route tracking
BlueNav also integrates automated navigation functions. The system can follow a route composed of GPS points. Once the waypoints have been defined, the boat automatically adapts its course and speed. Cruise Control stabilizes the boat's speed.
In Dutch canals, where speed is strictly limited, this system prevents unintentional variations. It can also be used on repetitive routes, for example on a boat used for tourist transport or port surveillance.
A system that can be adapted to existing boats
The set-up tested on this Aluship 670 remains unusual. Two 8 kW pods installed on a boat less than seven meters long constitute the first configuration of this type.
But the BlueNav system is not limited to new boats. The pods can also be retrofitted to existing aluminum, steel or composite units. According to the manufacturer, two 8 kW pods can equip boats up to around 12 m and 12 tons. The technology received an award at the Electric and Hybrid Marine Expo in Amsterdam in June 2025, in the propulsion technology of the year category.
The test sailing took place in the bitterly cold weather typical of a Dutch winter. And in this setting of bricks and calm water, the silence of the electric pods contrasted sharply with the usual urban rumble.
For Marius Hondema, this atypical montage is a success:
"I wanted to understand how far you can go with hybrid propulsion on a small boat. Pods aren't just for getting ahead, they also change the way you manoeuvre explains the boat's owner.
