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This engine is suitable for boats with displacement of 5-6 tons with a water line legth (LWL) of 27-34 feet.

Horse Power




Cubic Capacity




25 @ 3600 rpm




898cc / 54.8 ci

118kg / 260 lbs


40 Amp

Technical Specifications

Beta 25 with label.jpg

Beta 25 with label.jpg



The Beta 25 is a 3 cylinder, naturally aspirated, diesel propulsion engine developing 25 bhp at 3,600 rpm with a swept volume of 898 cc.

The Beta 25 Diesel Propulsion Engine

Standard Options

14.5″ (370mm) mount centers

40 Amp alternator

ABV Instrument Panel

Flexible coupling

Flexible mounts

Heat exchanger cooling

High Inertia Flywheel

Intake silencer / Air filter

Oil change pump (fitted)

Shaft Coupling

Shallow oil pan

Standard exhaust injection elbow

Stop solenoid

TMC 40 transmission

Transmission Options

standard – TMC 40


Bobtail - No gearbox but with drive plate


TMC 401.45:1 / 2:1 / 2.6:1   


TMC 60Twin disc/Technodrive 1.55:1 / 2:1 / 2.45:1 / 2.83:1  


TMC 60A 7 degree down angle 2:1 / 2.45:1


TMC 60 Oil Coolerfor running LH in Ahead (NOT for TMC60A)


PRM 80 2:1 / 2.5:1


PRM 120 2.04:1 / 2.5:1 / 2.94:1


ZF 15MIV2.13:1 / 2.99:1

Upgrade Options

Alternator (standard) w/ Serpentine Belt System

Alternator 75 amp w/ Serpentine Belt Drive System

High Rise Exhaust Elbow for 1-5/8″ hose

High Rise Exhaust Elbow for 2″ hose – 150mm rise

High Rise Exhaust Elbow for 2″ hose – 200mm rise

High Rise Exhaust Elbow for 2″ hose – Volvo style cross over

Panel – Type ABVW Waterproof

Panel – Type B

Panel – Type C   click here for panel dimensions

Panel – Type CW Waterproof

More Options

Adverc Controller

Flybridge Panel

Hot water Fittings

Insulated Ground Electrical w/ 70 amp Alt

Keel cooling

Long term storage (test run on Ensis oil and Calibration fluid)

Mount and pulley for Sea Frost compressor

Mounts @ 11.5″ centers (Atomic 4)

Mounts @ 16″ Centers (Albin Vega)

Mounts @ 17″ Centers (Farymann A30)

Panel – Type A

Panel Extension harness with starter relay

Panel Recess with clear lid for B panel

Panel Recess with clear lid for C panel   click here for recess dimensions

PTO Pulley (twin A sections)

Remote Oil Filter

Standard oil pan

Operator's Manual

Data Sheet

Downloads & Support

Schematics with TMC 40

Schematics with TMC 60

Schematics with ZF15

Beta 25 Bobtail

Beta 25 Atomic 4 Replacement

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