Retractable electric motor simplifies hybrid boat conversion

The BlueNav Bluespin system is a fast and simple solution for hybrid boat conversion. A retractable electric motor, easily adapted to any boat, allows the pilot to switch from fossil fuel to electric propulsion at the touch of a button.

There are thousands of boat owners – both recreational and workboat – who would like to reduce their reliance on fossil fuels, but find it difficult to switch to all electric propulsion. Some need or want to be able to travel for long distances at high speeds, while others may occasionally need a significant power boost for towing or other reasons.

They also want or need an electric motor sometimes – maybe to cruise at a leisurely pace without the noise and odour of gas or diesel, or save fuel costs by operating on electricity in harbours and slow zones.

Batteries are simply not at the stage of development necessary to meet all the demands for these owners, but many hybrid options require an overhaul of a vessel’s entire propulsion system, which can be both expensive and time consuming.

Award winning hybrid boat conversion system

Enter Herve Frouin and his team at BlueNav. They came up with a hybrid boat conversion that is one of those ideas so simple in concept you might say ‘why didn’t I think of that?’

They have engineered a self-contained retractable rim electric motor that can be added to a boat without any alteration to the boat’s structural elements or changing the location or operation of existing combustion engines.

Many boat and marine organizations and shows are impressed. Since its introduction the BlueSpin has won the France edition of the Global Green Business Ideas Competition, was nominated in the Dame Design Awards of METSTRADE and took top honours for Best Product 2021 at the Innovation Awards of the Salon Nautique Paris in December.

hybrid boat conversion shown on 'The Rock Emperor' The Rock Emperor shown here is a great example of the BlueSpin in action. She is an open picnic style speedboat from the Dubourdieu shipyard in France – 12 meters long (39 ft), weighing 6 tons – and is equipped with two 250HP outboard ICE engines and two 15kW BlueSpin Retractable electric motors under the transom extension. The large image at the top of this page shows the installation more clearly.

The big fossil fuel burners are used to quickly take the passengers out to open water or a remote location. When the Rock Emperor pilot wants to switch to electric power, controls at the helm raise the outboards and the electric rim thrusters are extended from the BlueSpin system.

The only intrusive interior modification with the system is the addition of the batteries, wiring and cabling for electricity flow and steering/throttle control.

Suitable for wide variety of boats

BlueNav has also developed a HMI (Human Machine Interface) that analyzes data about current, position and speed to assist the pilot in switching from one propulsion system to the the other. The system integrates with all major electronic navigation systems and will also be augmented with options like self parking and dynamic positioning – the ability to have the thrusters maintain a constant boat position for fishing or swimming.

hybrid boat conversion examples - outboard fossil fuel, sailboat, inboard fossil fuel

The BlueSpin system is also an option for hybrid conversion on boats with inboard ICE motors or for sailboats. A non-retractable BlueSpin can be attached to a boat’s hull with the same minor battery and cabling components as the retractable version and in the case of sailboats, the containing box of the electric motor is designed to easily install in the hull opening of the most common diesel saildrives.

In all cases the motors are rim motors, meaning the propeller blades are not attached to a central hub but are mounted on an outside ring that is part of the motor itself.  They are especially efficient for the low speed applications that are often the electric part of hybrid boat conversions.

BlueSpin motors come in power ratings of 15, 20, 30 and 50 kWs (≈ 20, 30, 45 and 70 hp). The portfolio section of the BlueNav website shows a variety of hybrid boat conversions that are in operation now.

hybrid boat conversion on the Strad pilot boat

The Night Ocean speedboat has two 370HP inboard ICE engines and twin 15kW BlueSpin Retractable motors mounted below her swim platform. The 8 ton pilot boat Strad has a single 65HP combustion engine and two retractable 10kW BlueSpins and the Tulum, a 14 m (46 feet) traditional pinasse, has two 15kW BlueSpin Stationary motors. The boats have electric autonomy range of 4 to 5 hours at 6 or 7 knots.

In addition to the BlueSpin hybrid boat conversion system, BlueNav can also provide all electric propulsion systems. Their BlueDrive S20 Liquid is a 15 kW (20 hp) inboard available with air or liquid cooling. The BlueSail S15 Liquid is a 10 kw (15 hp) standard electric saildrive – non retractable, with hub propeller blades.

One of the things that separates electric boats from electric cars is that cars generally operate on roads whereas boats operate in all different kinds of waters with all different kinds of uses. For many of those uses a battery powered system is perfect, but for others a combination of fossil fuel and electric is best. The BlueSpin is a hybrid boat conversion option that can be used as a transitional phase in a move to all-electric or as a long term hybrid solution.

Exciting things are happening every day in electric boats and boating.
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2 thoughts on “Retractable electric motor simplifies hybrid boat conversion

  • May 9, 2023 at 5:35 am

    It’s a beautiful thing . Let’s save this planet

  • March 30, 2024 at 5:37 pm

    would love to trail this on my snapdragon 24 yacht in UK


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