Westerbeke 12 B/C/D Two

“Two cylinder,four cycle smoothness in a lightweight, compact engine”

When Westerbeke introduced the 12-B-Two in 1983 they proudly described it as having “the smallest envelope” available. Undoubtedly compact, these low profile diesels were easy to install, easy on fuel and easy to service. The engines featured;

  • Fresh water cooling as standard
  • The engine was pre-wired to plug-in connector for ease of installation
  • A self-bleeding fuel system made running out of fuel or changing filters less of a major issue
  • A 12 volt, 35 ampere alternator charged the vessel’s battery bank quickly without too much strain on the engine.
  • Flow control domestic hot water connections as standard brought comfort on board
  • A coolant recovery tank was fitted as standard
  • Throttle, stop, and shift control brackets were fitted
  • Low oil pressure and high water temperature alarms kept the engine safe
  • Glow plug cold starting aid made winter use possible
  • Four point adjustable flex engine mounts made installation easier
  • A lube oil drain hose made changing the engine oil much easier
  • A flexible fuel supply and return connector again made installation much more straightforward

Power and Efficiency

Whilst keeping the engine simple, Westerbeke delivered power and efficiency in a reliable and compact unit. 12hp was generated at 3600 rpm.


With a conventional two-cylinder vertical in-line design, the 12B Two was naturally aspirated and developed a compression ratio of 25:1.

FeatureWesterbeke 12B Two
Configuration4-stroke, vertical, fresh water-cooled diesel engine
Maximum output at crankshaft12 hp@3600 rpm
Displacement0.45 litres
27.52 cu. in.
Bore x stroke 65 mm x 68 mm
2.56 in x 2.68 in
Combustion systemswirl type pre-combustion chamber
Starting systemElectric starting 12V with solenoid activated shift
Alternator12V – 35A
Cooling system4qt (3.78 litre) coolant.
Lubrication system Enclosed, forced lubricating system by gear pump
Direction of rotation [crankshaft]Counterclockwise viewed from flywheel side
Dry weight with gear92.9 kg
205 lbs

Video: Click to watch a short video of a Westerbeke 12C-Two running