3YM20 21HP

Request a Quote

SKU: web3YM20 Category:

21 mhp of Reliable Mechanical Power for Saildrive and Shaft Installations

The YANMAR 3YM20 is a 0.854 L, three-cylinder marine diesel rated at 15.3 kW / 21 mhp at 3600 rpm, the middle of the YM series, which covers 14 to 29 mhp in three output models. The YM series is YANMAR’s line of mechanical engines built for smaller sailboats and other pleasure craft, delivering reliable power and smooth performance for unforgettable on-water experiences, and an ideal solution for smaller recreational boats. YANMAR built the series around five things: clean, interconnective, quiet, powerful and fuel efficient.

Powerful and fuel efficient. YANMAR’s mechanical indirect injection, in-line pump fuel system gives the YM series a compact design with impressive power output, with fuel consumption optimized to maximize cost-effectiveness and efficiency.

Clean and quiet. The 3YM20 meets EPA Tier 3 and EU RCD 2 and produces minimal emissions thanks to its advanced technology, and is engineered for minimal noise and smooth operation.

Interconnective. The 3YM20 is controlled by YANMAR’s B20 mechanical panel, showing engine hours, battery voltage and alarms, with an optional fuel level gauge. The 3YM20 is offered with the YANMAR SD25 saildrive or, for shaft drive, with the Kanzaki KM2P-1 gear.

  • Powerful: 15.3 kW / 21 mhp at 3600 rpm, compact design with impressive power output
  • Fuel efficient: fuel consumption optimized to maximize cost-effectiveness and efficiency
  • Clean: meets EPA Tier 3 and EU RCD 2, minimal emissions
  • Quiet: engineered for minimal noise and smooth operation
  • Interconnective: B20 mechanical panel standard
  • SD25 saildrive or shaft drive with the Kanzaki gear, 110 kg / 243 lb dry weight without gear

Spec sheets

Manuals

Drawings

Specification Value
Rated output 15.3 kW / 21 mhp
Rated speed 3600 rpm
Configuration 3-cylinder in-line, 4-stroke, vertical, water-cooled diesel
Displacement 0.854 L / 52.1 cu. in
Bore x stroke 70 mm x 74 mm / 2.75 in x 2.91 in
Aspiration Naturally aspirated
Fuel system Indirect injection, in-line pump
Cooling Fresh water cooled with heat exchanger
Alternator 12 V, 125 A
Dry weight, without gear 110 kg / 243 lb
Dry weight, with KM2P-1 gear 120 kg / 265 lb
Dry weight, with SD25 saildrive 140 kg / 309 lb
Dimensions, L x W x H 613 mm x 463 mm x 600 mm
Drive options SD25 saildrive; shaft (KM2P-1 gear)
Controls Mechanical; B20 panel standard
Emissions compliance EU: RCD 2, BSO II, EMC. US: EPA Tier 3, EPA-C.
YANMAR SD25 saildrive

SD25 saildrive

YANMAR designed and developed the SD25 saildrive to match its YM series engines, the 2YM15, 3YM20 and 3YM30AE. It connects directly to the engine’s dedicated marine housing without adapters or couplings, which keeps the propulsion system compact and reduces rotational mass and vibration.

Specification Value
Type Saildrive
Clutch Constant mesh gear with dog clutch
Reduction ratios 2.64
Dry weight 30 kg / 66 lb

Shaft drive gears

For shaft-drive installations the 3YM20 is supplied with the marine gears below. The gear uses a mechanical cone clutch. Other marine gearboxes and configurations are available on request; ask Mastry for the right match to your hull.

Gear Type Reduction ratios Gear dry weight
Kanzaki KM2P-1 Parallel 2.21 9.8 kg / 22 lb
YANMAR B20 tachometer panel

B20 panel

Start/stop tachometer panel for YANMAR’s YM series mechanical engines, with tachometer and pre-heat control. Shows engine hours and battery voltage, displays engine alarms and can drive an optional fuel level gauge.