The Yanmar 3YM20XSD25 is a 3-cylinder, 4-stroke, vertical water-cooled marine diesel engine designed for sailboats and smaller motorboats, frequently configured with the SD25 saildrive. It is known for its compact design, quiet operation, and compliance with EPA Tier 3 and RCD 2 environmental standards.
Key specifications for the engine and SD25 saildrive include:
Engine Performance & Technical Data
- Maximum Output (Crankshaft): 15.3 kW / 21 mhp at a rated speed of 3600 rpm
- Displacement: 0.854 L (52.1 cu in)
- Bore x Stroke: 70 mm x 74 mm (2.76 in x 2.91 in)
- Combustion System: Indirect injection
- Aspiration: Natural
- Direction of Rotation: Counterclockwise viewed from stern
- Compression Ratio: 23.5:1
- Fuel Consumption: Approximately 1.8 litres/hour at cruising speed
Dimensions & Weight (Engine with Saildrive SD25)
- Dry Weight: Approx. 144 kg (317 lbs)
- Dimensions (Length x Width x Height): 873 mm x 463 mm x 600 mm
Saildrive (SD25) Specifications
- Type: Constant mesh gear with dog clutch
- Reduction Ratio (Forward/Reverse): 2.64 / 2.64
- Direction of Rotation: Counterclockwise
- Dry Weight (Saildrive unit): 30 kg
Standard Features & Equipment
The engine includes a fresh water cooling system with heat exchanger, a 12V – 125A alternator, mechanical engine management, and a 12V – 1.4 kW electric starter. Standard components include a B20 panel, flexible mounts, exhaust mixing elbow, and electric stop solenoid.
The engine includes a fresh water cooling system with heat exchanger, a 12V – 125A alternator, mechanical engine management, and a 12V – 1.4 kW electric starter. Standard components include a B20 panel, flexible mounts, exhaust mixing elbow, and electric stop solenoid.
Optional Accessories
Optional accessories such as a high-riser mixing elbow, hot water kit, and various extension wire harnesses are available.
Optional accessories such as a high-riser mixing elbow, hot water kit, and various extension wire harnesses are available.












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