Overview
ISO 8665:2006 - "Small craft - Marine propulsion reciprocating internal combustion engines - Power measurements and declarations" specifies the additional requirements (beyond ISO 15550) for determining and declaring the rated power of reciprocating internal combustion (RIC) engines used to propel recreational and small craft up to 24 m hull length. It is intended to be used in conjunction with ISO 15550 and defines test, reporting and declaration practices so manufacturer power ratings are reproducible and verifiable.
Key topics and requirements
- Scope: Applies to marine propulsion RIC engines for recreational and small craft (≤ 24 m hull length).
- Test method: Uses method No. 2 of ISO 15550 (engine dynamometer testing) with the additional conditions and supplements given in ISO 8665:2006.
- Test conditions: Specifies representative engine/system configuration, removal or idling of non-essential auxiliaries, fuel and lubrication requirements, intake and exhaust pressure limits, and cooling-water temperature limits (e.g., cooling inlet ~298 K with specified tolerances).
- Fuel and oil: Diesel test-fuel property limits are given (density, kinematic viscosity and cetane index references per ISO 3675, ISO 3104 and ISO 5165); lubricating oil must meet engine manufacturer specifications.
- Exhaust and intake pressures: Limits on exhaust back pressure and intake ventilation pressure relative to barometric pressure (±0.75 kPa) are specified to ensure consistent power measurement.
- Power declaration and reporting:
- Power declarations must include the associated engine speed (rpm) and indicate whether power is at the propeller shaft or crankshaft.
- Maximum allowable exhaust back-pressure for obtaining declared power must be stated.
- Full test report data items are listed (rpm, torque, ambient and intake temperatures/pressures, fuel temperature for diesels, correction factor, cooling water pressures/temperatures, optional items such as fuel consumption).
- Production conformity tolerances:
- ±5% for engines or propulsion systems >100 kW with speed limiters.
- ±10% or ±0.45 kW (whichever is larger) for other engines/systems.
Applications and users
ISO 8665:2006 is used by:
- Engine manufacturers and OEMs to document and publish rated power.
- Independent test laboratories and engine dyno facilities for type and production testing.
- Certification bodies, marine surveyors and regulatory authorities verifying declared power.
- Naval architects and boat builders matching engines to propellers and propulsion systems.
Related standards
Keywords: ISO 8665:2006, marine propulsion, small craft, reciprocating internal combustion engine, power measurements, rated power declaration, engine testing, exhaust back pressure, production conformity.
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