Overview
ISO 22098:2020 - Ships and marine technology - Full‑scale test method for propeller cavitation observation and hull pressure measurement - specifies a standardized full‑scale test process to observe propeller cavitation and measure associated hull pressure fluctuations. The standard defines instrumentation and implementation, construction and safety requirements, test procedures, data processing and reporting. It applies to ships during construction (before/during sea trials) and after delivery, supporting validation of model tests, CFD predictions and root‑cause investigations of vibration, noise and blade damage.
Key topics and technical requirements
- Test objective: Investigate propeller cavitation behaviour and its effects on hull vibration and pressure fluctuations.
- Observation methods:
- Traditional CCD camera with stroboscopic lighting (time‑lapse or low‑frequency imaging).
- High‑speed camera in daylight for detailed, high‑frequency imaging; cameras should support synchronization where multiple units are used.
- High‑speed bore‑scope (small M20 bore penetrations) for rapid installation without dry‑docking; dependent on daylight and water quality.
- Observation windows:
- Designed for visibility, ease of setup, structural safety and watertightness.
- Typical components: steel cover and frames, acrylic window glass, O‑ring seals.
- Window sizes and locations selected via 3D CAD analysis of stern structure; adherence to structural verification or class approval is required.
- Hull pressure measurement:
- Pressure transducers mounted on stern surface near propeller plane; recommended minimum of 5 transducers where possible.
- Typical transducer coverage: ~0.8D forward of propeller plane to ~0.6D aft; transverse extension ~0.6D–0.8D; spacing ~0.15D–0.35D (D = propeller diameter).
- Example transducer characteristics in the standard: rated to 345 kPa, frequency range 0 Hz–6 000 Hz (water).
- Transducers must be calibrated per manufacturer’s reference; use signal processors and data systems for analysis.
- Safety & construction: ensure structural strength, watertight integrity and safe access; select installation routes and workspace during design/construction review.
- Reporting: documented test procedures, instrumentation, calibration, data processing and results to support correlation with model tests or CFD.
Applications and who uses it
- Shipbuilders and naval architects validating propeller design and cavitation predictions.
- Ship operators and yards conducting sea trials or post‑delivery investigations into vibration, noise or blade erosion.
- Classification societies, test engineers and researchers performing full‑scale verification to improve model‑ship correlation and CFD validation.
- Propeller and propulsion system designers seeking empirical data for performance tuning.
Related standards and notes
- The standard references established definitions for windows and scuttles as in IACS UI (e.g., LL62) and IMO Resolution MSC.143(77).
- ISO 22098:2020 complements model testing practices and CFD validation workflows used in ship hydrodynamics and propulsion design.
Keywords: ISO 22098:2020, propeller cavitation, hull pressure measurement, full‑scale test, observation window, high‑speed camera, pressure transducer, sea trial, ship vibration, cavitation observation.