The latest in a series of new-generation compact diesels from Yanmar Marine is its three-cylinder 3YM20, developing 21HP (15.3kW) at 3,600 rpm. Displacement is 0.854 litres. The naturally aspirated 3YM20 features a completely redesigned cylinder block and combustion system, configured for quietest possible, vibration-free running. It is a vertical four-stroke, fresh water cooled. With indirect injection and a swirl pre-combustion chamber, this all-new unit complies with EPA Tier 2 and BSO/SAV Stage 2 emissions regulations. A compact control panel, injection pump, electric stop solenoid and 60-amp alternator are introduced as standard. To meet heavier electrical demands, an 80-amp alternator is offered as an option. Maintenance has been simplified, with the water pump, fuel filter, oil change and dip stick located on the same side of the engine, at the front. This engine is available as a standard inboard, or with Yanmar’s double-seal saildrive unit. The inboard has a servo-cone clutch with a choice of 2.21:1, 2.62:1 and 3.22:1 forward ratios, plus 3.06:1 in reverse. The saildrive version, designated 3YM20C, has a constant mesh dog clutch, geared at 2.64:1 forward and reverse. In recent months, Yanmar Marine has introduced new diesels for sailboats and smaller motor boats at 29HP (21.3kW), 39HP (28.7kW) and 54HP (39.6kW). The 3YM20 at 21HP replaces Yanmar’s 2GM20 and provides around 17% more power
| Technical Specification | Value |
|---|---|
| Power (Crankshaft) | 15.3 kW (21 hp) @ 3600 rpm |
| Full throttle operating speed | 3200–3600 rpm |
| Displacement | 0.854 litre |
| Bore × Stroke | 70 mm × 74 mm |
| Cylinders | 3 |
| Combustion system | Indirect injection, swirl pre-combustion chamber |
| Alternator | 60 A (80 A option) |
| Cooling system | Fresh water cooling with heat exchanger |
