ISO 22098:2020

INTERNATIONAL ISO
STANDARD 22098
First edition
2020-05
Ships and marine technology —
Full-scale test method for propeller
cavitation observation and hull
pressure measurement
Navires et technologie maritime — Méthode d'essai grandeur nature
pour l'observation de la cavitation de l'hélice et le mesurage de la
pression de la coque
Reference number
ISO 22098:2020(E)
©
ISO 2020

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ISO 22098:2020(E)

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© ISO 2020
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ISO 22098:2020(E)

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Instrumentation and implementation . 2
4.1 General . 2
4.2 Cavitation observation . 2
4.2.1 General. 2
4.2.2 Cavitation observation method . 2
4.2.3 Observation window . 3
4.2.4 High-speed camera . 5
4.3 Hull pressure measurement . 5
4.3.1 General. 5
4.3.2 Pressure transducer . 5
4.3.3 Pulse controller . 7
4.3.4 Data processing system. 7
5 Construction requirements . 7
5.1 General application . 7
5.2 Safety clearance and water-tightness. 8
6 Test and measurement procedure . 8
7 Reporting . 9
Annex A (informative) Example of configuration of cavitation observation .10
Annex B (informative) Analysis of fluctuating pressure signals .11
Bibliography .12
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ISO 22098:2020(E)

Foreword
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ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
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This document was prepared by Technical Committee ISO/TC 8, Ships and marine technology,
Subcommittee SC 8, Ship design.
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ISO 22098:2020(E)

Introduction
Cavitation is responsible for significant propeller performance degradation and occurs at nearly all
propellers, causing often vibrations, noise and propeller blade erosion. It has been a common practice to
evaluate the propeller cavitation behaviour and its related hull pressure through model tests. However,
the model test might not show the full-scale cavitation phenomena.
Full-scale cavitation observations and hull pressure measurements are very helpful as feedback for
propeller design and prediction of full-scale performance through model test. This full-scale test method
is needed to establish more accurate model-ship correlation, to come up with better experimental
methods and to identify the cause of unexpected problems such as blade damage.
This document was developed to provide a standardized full-scale test method for propeller cavitation
observation and hull pressure measurement.
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INTERNATIONAL STANDARD ISO 22098:2020(E)
Ships and marine technology — Full-scale test method
for propeller cavitation observation and hull pressure
measurement
1 Scope
This document specifies a full-scale test method for propeller cavitation observation and hull pressure
measurement. The objective of the test is to investigate the propeller cavitation behaviour and its
effects on the hull vibration problems.
The test method comprises the specification of the test instrumentation and implementation,
construction requirements to ensure structural safety, test and measurement procedures, and
reporting documentation.
This document is applicable to ships in the following stages:
— before or during sea-trial, prior to delivery stage (vessels under constructions), and
— after delivery stage.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
measured ship speed
ship’s speed during a speed run derived from the headway distance between start and end position and
the elapsed time of the speed run
3.2
observation window
transparent window allowing to observe and investigate the occurrence of cavitation of a ship propeller
3.3
propeller plane
plane normal to the shaft axis and containing the propeller reference line, i.e. contain the reference
point of the root section
3.4
ship speed
speed of the ship that is realised under stipulated conditions
Note 1 to entry: See also measured ship speed (3.1).
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ISO 22098:2020(E)

3.5
side scuttle
2
round or oval opening with an area not exceeding 0,16 m
2
Note 1 to entry: Round or oval openings with an area exceeding 0,16 m are “windows”, as defined in IACS UI
[3] [4]
LL62 or IMO Resolution MSC. 143(77) .
3.6
sea chest
fitting in a hull below the water line, for admitting or discharging water
4 Instrumentation and implementation
4.1 General
For the ship installation of all test equipment, it is necessary to thoroughly review the drawings on the
ship subject to test, and the selection of sensor and equipment installation location, workspace and
transportation route should be reflected in the design and construction stage.
4.2 Cavitation observation
4.2.1 General
Various methods for observing full-scale cavitation have been developed so far. This document
introduces the characteristic of various cavitation observation methods and specifies the criteria for
the necessary preparations for the cavitation observation test.
4.2.2 Cavitation observation method
A traditional method using a CCD camera with a stroboscopic lighting source has been commonly
used for full-scale cavitation observation. Recently, a technique using a high-speed camera in daylight
condition has been used. This technique minimizes the number of observation windows compared to the
traditional method and enables to observe detailed motion of cavitation to study the phenomenological
behaviour of the cavitation.
Furthermore, instead of the existing observation window, a high-speed bore-scope technique has been
used in consideration of relative installation time and cost reduction. The small penetrations needed
for the bore-scope equipment can be drilled with the ship in a float condition, which reduces the
installation time from days to hours and saves money from expensive ship docking operations.
However, the high-speed bore-scope technique requires strong sun light and good water quality.
The observation windows are more robust against the weather conditions and sea conditions. Thus,
observation windows are still useful if there is sufficient construction time and space. Appropriate
equipment should be selected depending on the purpose, situation and timing of the installation.
Although frequency of image heavily depends on illumination condition, Table 1 shows several examples
of various observation methods for full-scale propeller cavitation.
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ISO 22098:2020(E)

Table 1 — Examples of cavitation observation methods
Dry docking
Window/ Dependence
Observation method required for Comments
hole size on daylight
preparation
Easily affected by the environment
Photographs/videos
about (daylight, water quality, etc.)
in daylight no yes
M20 bores Easy installation
using a bore-scope
Low frequency image
Moderately affected by the environment
Photographs/videos about
(daylight, water quality, etc.)
in daylight 200 mm to yes yes
To be installed during docking
using windows 300 mm
Low frequency image
Moderately affected by the environment
High speed camera about
(daylight, water quality, etc.)
in daylight 200 mm to yes yes
To be installed during docking
using windows 300 mm
High frequency image
Easily affected by the environment
High speed camera (daylight, water qu
...