YANMAR 3YM20 21HP Marine Inboard Engine – Compact Power and Fuel-Efficient Performance | JB Marine GmbH
JB Marine GmbH, Germany’s trusted Yanmar distributor, proudly offers the YANMAR 3YM20 21HP Diesel Marine Inboard Engine, a perfectly balanced combination of power, reliability, and efficiency in a compact design.
Engineered for small to mid-sized sailing yachts, catamarans, and motorboats, this naturally aspirated, 3-cylinder diesel engine delivers 21 horsepower at 3,600 RPM, providing smooth propulsion with low noise, minimal vibration, and exceptional fuel economy.
Built for Performance and Reliability
The YANMAR 3YM20 is designed to perform flawlessly in both new builds and repowering projects, offering proven Yanmar durability in a lightweight configuration.
Its freshwater-cooled, heat-exchanger system and advanced diesel combustion technology ensure optimal operating temperatures, reduced emissions, and long-term performance in all marine conditions.
Fully compliant with IMO Tier II and EPA Tier II standards, it delivers an eco-friendly boating experience without sacrificing power or responsiveness.
Key Features of the YANMAR 3YM20 21HP Marine Inboard Engine
Compact and Lightweight Design
At just 114 kg (251 lbs), the 3YM20 is one of the lightest engines in its class, perfect for compact engine compartments.
Naturally Aspirated Power
Delivers 21 HP at 3,600 RPM, ensuring consistent and smooth propulsion for small yachts and boats.
Eco-Friendly Operation
Complies fully with IMO Tier II and EPA Tier II regulations for reduced emissions and cleaner performance.
Low Noise and Vibration
Precision-engineered for quieter cruising, offering maximum comfort for leisure and charter applications.
Fuel Efficiency and Ease of Maintenance
Yanmar’s advanced diesel system minimizes fuel use and simplifies routine servicing.
Durable Marine-Grade Construction
Corrosion-resistant components and a robust block design ensure long-term reliability in harsh saltwater environments.
Technical Specifications – YANMAR 3YM20 21HP Diesel Marine Engine
| Specification | Details |
|---|---|
| Model Name | YANMAR 3YM20 |
| Engine Type | 3-Cylinder, 4-Stroke, Naturally Aspirated |
| Displacement | 0.854 L (52.1 cu in) |
| Rated Output | 21 HP / 3,600 RPM |
| Fuel Type | Diesel |
| Cooling System | Freshwater with Heat Exchanger |
| Weight (Dry) | 114 kg / 251 lbs |
| Dimensions (L × W × H) | 593 mm × 450 mm × 527 mm |
| Certifications | IMO Tier II, EPA Tier II |
| Gearbox | Factory Installed (KM2P-1) |
| Alternator | 12 V – 125 A |
| Warranty | 5 Years Manufacturer’s Warranty |
Package Includes
When you purchase the YANMAR 3YM20 Diesel Marine Engine from JB Marine GmbH, your package includes:
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Yanmar 3YM20 engine (brand new)
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Factory-installed gearbox (KM2P-1)
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Freshwater heat-exchanger cooling system
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Starter motor and 12 V – 125 A alternator
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Flexible mounts for reduced vibration
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Fuel pre-filter with water separator
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Exhaust mixing elbow (L-Type)
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5 m wiring harness
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Freshwater expansion tank
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Belt safety cover
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Installation and operation manuals
All engines are factory-tested and Yanmar-certified for reliability and performance.
Optional Accessories
Enhance your propulsion system with genuine Yanmar accessories:
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High-riser exhaust mixing elbow
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Secondary alternator (12 V – 125 A / 24 V – 60 A)
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VC10 Vessel Control System
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NMEA2000 engine monitoring interface
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Extended wiring harness (3 m / 5 m / 10 m)
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Onboard spare parts kit
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Hot-water kit for domestic systems
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Propeller cone nut kit KM2P
All optional parts are OEM certified, ensuring seamless integration and long-term durability.
Applications
The YANMAR 3YM20 is perfectly suited for:
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Small to medium sailing yachts
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Catamarans up to 30 ft
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Motorboats and sloops
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Light-duty fishing vessels
Its compact, low-noise design makes it ideal for recreational cruisers, training boats, and light commercial craft.
Warranty and After-Sales Support
All Yanmar marine diesel engines purchased from JB Marine GmbH include:
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5-Year Manufacturer’s Warranty against defects
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Optional extended service plans
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Access to Yanmar’s global service network
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Genuine parts and certified technicians
Our dedicated team offers installation support, maintenance services, and technical guidance to keep your engine running at peak efficiency.
Frequently Asked Questions (FAQs)
What makes the Yanmar 3YM20 unique?
Its compact footprint, light weight, and high fuel efficiency make it ideal for smaller vessels without sacrificing performance.
Does it include a gearbox?
Yes — the 3YM20 comes with a factory-installed KM2P-1 gearbox for seamless installation.
Is the engine fuel-efficient?
Absolutely. It’s optimized for low fuel consumption and long cruising range.
What boats is it best for?
Sailing yachts, catamarans, small motorboats, and light fishing vessels.
Is it environmentally friendly?
Yes — fully compliant with IMO Tier II and EPA Tier II standards.
Can I buy spare parts and accessories?
Yes, JB Marine GmbH supplies genuine Yanmar OEM spares and upgrades.
Do you offer installation services?
Yes, our marine engine experts provide professional installation and commissioning support.
Why Buy from JB Marine GmbH
JB Marine GmbH is an authorized Yanmar Marine dealer based in Germany, specializing in inboard diesel engines, marine repower solutions, and technical service.
Why customers choose us:
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Factory-backed warranty support
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Competitive pricing and bulk options
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Expert consultation for custom projects
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Fast global shipping
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Dedicated after-sales assistance
With JB Marine GmbH, you get more than an engine; you get a trusted partner in marine propulsion.
Order Your YANMAR 3YM20 21HP Engine Today
Discover the difference Yanmar engineering makes.
The YANMAR 3YM20 21HP Marine Inboard Engine delivers quiet, efficient power for vessels of every type, backed by Yanmar’s heritage of quality and JB Marine GmbH’s commitment to service.
Contact JB Marine GmbH today for pricing, delivery options, and custom configurations. Yanmar Power, Reliable Performance for Every Journey.
