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Switching from an internal combustion outboard motor to on-board electric propulsion is a trend that's gaining ground on small and medium-sized sailboats. On HÉLIOS, a 7.37 m Pizzicato designed by Jean-Pierre Villenave and built in plywood in 1993, the decision was made to do away with the 6 hp internal combustion engine and install a 3 kW electric Pod. The aim was not to increase engine performance, but to adapt navigation to a different approach.
With a length of 7.37 m, a waterline of 6.60 m, a displacement of around 2 tons and a draft of 0.75 m, the Pizzicato is a simple, light and seaworthy sailboat. The engine is mainly used for harbor entry and exit, anchoring maneuvers and securing an arrival before the current reverses.
Define the program before selecting the drive unit
The 6 HP petrol outboard fulfilled its role, but involved annual maintenance, fuel storage, noise and handling. For use limited to a few hours a week, the inboard diesel made little sense, both in terms of weight and cost.
Three options were compared:
- 6 HP petrol outboard, approx. 30 kg, moderate investment but recurring maintenance
- Diesel in-board 10 HP, approx. 140 kg, high installation costs and regular maintenance.
- 3 kW electric drive, approx. 100 kg including batteries, intermediate cost and virtually no maintenance.
For a 2-tonne boat that mainly sails, the compromise between power, simplicity and cost led to the choice of an electric Pod Drive ePropulsion 3.0 Evo.
A POD under the hull
The chosen motor develops 3 kW, a power level adapted to the boat's hull speed. Unlike an outboard, the Pod is installed under the hull, in the longitudinal axis.
This configuration demands particular attention to the structure. The Pod concentrates propulsion forces on a fixed point. The sole has therefore been reinforced with 20 mm marine plywood, epoxy-bonded between two stringers. The purpose of this reinforcement is to take up mechanical forces and secure the area in the event of impact or grounding.
The motor is perfectly aligned with the axis of the boat and parallel to the waterline to optimize efficiency and avoid any parasitic vibration.
Batteries and electrical architecture
The system is based on two E60 batteries, with a total capacity of around 6 kWh. They are installed in the former engine compartment, under the companionway, on a 20 mm marine plywood floor supported by two varangues.
The support is epoxy-saturated to prevent warping over time. The charger is positioned above the batteries, with short, accessible and protected wiring.
The entire installation, excluding the study phase, took around ten hours to complete.
Performance measured at sea
The tests were carried out in calm seas.
At 1,500 W, the yacht reaches 4.3 knots, close to its hull speed. Increasing power by a further 1,500 W brings a gain of only 0.9 knots, with a significant drop in range. Efficiency then becomes unfavorable.
At 1,500 W, range is around 4 hours, or 17 miles. Consumption represents around 25% of battery capacity per hour at this speed.
Cruising feedback
Over a week's sailing from Arradon, with a route including Hoëdic, Belle-Île and return to the Gulf, i.e. around 82 miles, engine use was limited to two effective hours, corresponding to around 8 miles of motoring.
Total consumption over the week represented around 50% of battery capacity. One hour was spent maneuvering in and out of harbors, and another securing an arrival before a current reversal.
The rest of the time, the boat sailed exclusively under sail.
Limits and energy security
In the event of strong winds or strong adverse currents, the energy reserve could become limiting. We recommend taking on board a small 2,000 W generator to recharge the batteries in a degraded situation.
Hydro-generation recharging remains marginal at speeds below 5 knots. The on-board solar panel is reserved for servicing.
What electric propulsion really means
On a daily basis, the change is noticeable. Total silence, absence of vibration, immediate torque for harbor maneuvers, and the elimination of on-board fuel all change the way the boat is used.
The precision of the electric torque facilitates approaches and U-turns in tight spaces. No engine maintenance reduces the annual technical workload.
On a light sailboat like the Pizzicato, electric propulsion is not a quest for maximum performance, but a coherent adjustment to a coastal cruising program. Conversion requires us to think differently about energy, and to accept controlled rather than excessive power.
In this particular case, the transformation was not limited to replacing an engine. It involved adapting the navigation as closely as possible to the boat's actual program, giving priority to sailing and reserving propulsion for strictly necessary phases.
