Overview - ISO 20083-2:2019 (Optical reflection method)
ISO 20083-2:2019, part of the ISO 20083 series on ships and marine technology, specifies a procedure for determining shaft power of ship propulsion systems by measuring shaft distortion with an optical reflection type device. The standard defines measurement principles, device components, calculation methods, calibration procedures, accuracy factors and required on‑board documentation for a shaft power meter using a torsion‑measurement optical system.
Key topics and technical requirements
- Measurement principle: Combines torsional deformation measurement and shaft revolution to calculate shaft torque and shaft power. The standard provides the mathematical relations linking torsional angle, polar moment of inertia, G‑modulus, revolutions per minute and output power.
- Device components: Specification of essential parts including two mounting rings, torsion meter (light source, slit, zoom lens, CCD), concave reflecting mirror, transmitter on the shaft, receiver/power‑supply system on the hull, and a revolution sensor.
- Optical detection: Uses reflected light captured by a CCD sensor; image magnification and the device calibration factor relate CCD counts to real displacement.
- Calculation method: Procedures and formulae to compute shaft torque from measured torsional deformation and to derive shaft power using shaft revolution rate.
- Accuracy factors: Identification of influencing parameters - shaft diameter, G‑modulus, distance between mounting rings, mounting ring thickness, shaft vibration, and zero adjustment - with guidance on reducing measurement uncertainty.
- Calibration and zeroing: Calibration procedure and sample calibration result form (informative annex) to ensure traceable and repeatable measurements.
- On‑board documentation: Required records and documentation for the installed device, calibration history and operational checks.
Applications and users
ISO 20083-2:2019 is intended for practical use in:
- Shipowners and operators monitoring engine output and fuel efficiency
- Marine engineers and technical crews performing on‑board shaft power tests
- Shipbuilders and naval architects verifying propulsion system performance during trials
- Classification societies, surveyors and testing laboratories conducting formal power assessments
- Manufacturers and installers of shaft power meters and optical torsion measurement systems
Typical applications include verifying main engine output, assessing vessel most‑efficient speed, monitoring propulsion system deterioration, and supporting maintenance planning or propeller/run‑in evaluations.
Related standards
- Part of the ISO 20083 series (see ISO website for the complete list). For national implementation details or further guidance, consult your national standards body or the ISO online catalogue.
Keywords: ISO 20083-2:2019, shaft power, shaft distortion, optical reflection method, torsion meter, shaft torque measurement, calibration, marine technology.