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Replacing a diesel engine with an electric motor often requires modifying part of the sailboat?s system. With its SDe saildrives, Yanmar aims to minimize mechanical work. However, the simplicity of installation does not eliminate the need to properly size the entire electrical system.
Yanmar Electric Saildrive: An Alternative to Diesel for Sailboats?
With its SDe line, Yanmar offers three electric saildrives?7, 10, and 15 kW?designed for sailboats up to approximately 12 meters. What sets them apart is that they make it easy to replace certain existing diesel engines without requiring major modifications to the hull.
A system designed to replace a diesel engine
Introduced in 2024, the SDe series integrates the electric motor, gearbox, controller, and cooling system into a compact unit. Yanmar announces compatibility with certain engine blocks from its YM diesel series.
The practical benefit for boat owners considering a engine replacement is that it minimizes the amount of modification work required. However, compatibility must be verified on a boat-by-boat basis. Replacing the engine does not eliminate the need to install batteries, electrical protection, and a charging system.
Cooling without using seawater
All three models operate at a rated voltage of 51.2 V. Cooling is provided by a closed-loop oil circulation system, without drawing in seawater to cool the electric motor.
This design eliminates some of the maintenance requirements associated with a diesel engine's cooling system. However, this does not mean that the saildrive is maintenance-free: the mounting base, seals, and lubrication still need to be monitored.
Battery life remains the deciding factor
During a test on a Saffier 33, the propulsion system reportedly operated for two hours at a power output of 2.5 kW, with 80% of the battery charge remaining. However, the available information does not provide sufficient details on the sailing conditions and battery capacity to determine a representative range.
For a recreational boater, the choice will therefore depend less on the saildrive's power alone than on the boating plan, onboard storage capacity, and recharging options.
The SDe can simplify the mechanical aspects of an electric conversion. But before switching away from diesel, it is still essential to estimate the cost of the entire installation and calculate the range based on the sailboat?s actual needs.
Prices range from 21,000 to 26,000 euros, excluding full installation
At the Dutch distributor Abma's Jachtwerf, the three models are listed at the following prices:
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SDe7 (7 kW): 20,981 %C2euros
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SDe10 (10 kW): 23,401 %C2euros
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SDe15 (15 kW): 25,821 %C2euros
These rates represent retail prices observed in the Netherlands and do not constitute an official French rate schedule. They do not reflect the cost of a complete conversion.
Yanmar notes that the batteries and propeller are not included in the standard package. You?ll also need to account for the charging system, electrical protection, wiring, and labor. The final cost will therefore depend heavily on the desired range and the equipment already on board.
