I
Rules for Classification and Construction
Ship Technology
1
Seagoing Ships
23
Harmony Class - Rules on Rating Noise and Vibration for Comfort,
Cargo Ships
Edition 2009
The following Rules come into force on July 15th, 2009
Germanischer Lloyd Aktiengesellschaft
Head Office
Vorsetzen 35, 20459 Hamburg, Germany
Phone: +49 40 36149-0
Fax: +49 40 36149-200
headoffice@gl-group.com
www.gl-group.com
"General Terms and Conditions" of the respective latest edition will be applicable
(see Rules for Classification and Construction, I - Ship Technology, Part 0 - Classification and Surveys).
Reproduction by printing or photostatic means is only permissible with the consent of
Germanischer Lloyd Aktiengesellschaft.
Published by: Germanischer Lloyd Aktiengesellschaft, Hamburg
Printed by: Gebrüder Braasch GmbH, Hamburg
Table of Contents
I - Part 1
GL 2009
Chapter 23
Page 3
Table of Contents
Section 1
A.
B.
C.
Section 2
A.
B.
C.
Section 3
A.
B.
C.
D.
Annex A
A.
B.
Classification
Scope ..........................................................................................................................................
Harmony Categories (hc) ...........................................................................................................
Class Notation ............................................................................................................................
Noise and Vibration Limits
General .......................................................................................................................................
Noise Limits and Tolerances ......................................................................................................
Vibration Limits and Tolerances ................................................................................................
2- 1
2- 1
2- 1
Required Measurements
General .......................................................................................................................................
Measuring Conditions ................................................................................................................
Performance of Measurements ...................................................................................................
Preparation and Documentation of Measurements .....................................................................
3333-
1
1
1
3
Standards
General .......................................................................................................................................
Standards ....................................................................................................................................
Annex B
Important Definitions
Annex C
Recommendations to Reduce Noise and Vibration
A.
B.
C.
D.
E.
1- 1
1- 1
1- 1
General .......................................................................................................................................
Considerations Regarding Excitation Forces .............................................................................
Theoretical Investigations ..........................................................................................................
Secondary Measures ...................................................................................................................
Supplementary Measurements during Production Phase ............................................................
A- 1
A- 1
CCCCC-
1
1
1
1
2
I - Part 1
GL 2009
Section 1
C
Classification
Chapter 23
Page 1–1
Section 1
Classification
A.
Scope
1.
In general, these Rules are based on national
and international standards listed in Annex A. They
will be adapted to the latest editions of these standards
when deemed necessary or will be modified to account for the progress of knowledge. The Rules reflect
the state of the art in vibration and acoustic technology.
2.
Some important definitions for expressions
used in these Rules are given in Annex B.
3.
Various comfort-promoting factors like furniture and size of cabins, the indoor climate, ship motions as well as the noise and vibration level decide on
the well-being of the crew and officers. In these Rules
only noise and vibration is dealt with.
4.
In this context, noise and vibration are defined as follows:
4.1
B.
Harmony Categories (hc)
1.
To allow for a graduation of noise and vibration levels, 3 harmony categories hc are introduced:
=ˆ ∗∗∗
hc = 2 =
ˆ ∗∗
hc = 3 =
ˆ ∗
hc = 1
high comfort
moderate comfort
acceptable comfort
2.
Respective limit values of noise and vibration
are defined in Section 2.
3.
Compliance with criteria given in these Rules
shall be verified through measurements performed under
defined conditions at specified locations, see Section 3.
Noise
Audible air pressure variations in the range of 16 Hz
to 16 kHz
4.2
10.
To reflect the different situation of small and
large cargo vessels with regard to noise and vibration
the limit values distinguish between an aft and a more
forward deck house position.
Vibration
Structural oscillations in the frequency range of 1 to
80 Hz
5.
The influence of ship motions on human wellbeing (seasickness) is not considered in these Rules.
6.
These Rules are intended to support owners
and shipyards to specify requirements regarding the
comfort of the crew on board seagoing cargo vessels.
7.
Requirements according to current regulations of the responsible flag state regarding maximum
noise and vibration levels in crew spaces are to be
fulfilled independently of these Rules.
8.
If the length between perpendiculars is less
than 80 m, limit values given in these Rules do not
apply. They shall be agreed upon separately after
conferring with Germanischer Lloyd (GL).
9.
The Rules do not give special requirements
for vessels with additional passenger cabins, but a
reasonable comfort level for this case is indicated.
C.
Class Notation
1.
Upon request, ships complying with these
Rules are granted the following special Notation of
Harmony Class
HC (hc).
2.
For a series of ships, the required noise
measurements are to be conducted individually for
each ship of the series. Regarding vibration measurements, a reduced measurement programme can be
accepted for sister ships.
3.
After modifications (e.g. conversions) that
might influence the noise and vibration behaviour, the
Class Notation is to be reconfirmed by GL.
4.
The Class Notation is granted on basis of the
measurement results attainted during the sea trials or a
later voyage on ballast draft by GL's own experts or
authorised companies.
If other loading conditions yield a substantially higher
noise or vibration level an additional measurement
voyage is required. If the noise or vibration level does
not meet the Class Notation, the Notation can be
downgraded, withdrawn or - provided that abatement
measures are foreseen - limited as to time.
I - Part 1
GL 2009
Section 2
C
Noise and Vibration Limits
Chapter 23
Page 2–1
Section 2
Noise and Vibration Limits
A.
General
1.
Requirements given in these Rules refer to
human wellbeing only.
However, to achieve a certain level of noise and vibration comfort it shall be ensured that main and auxiliary
machinery do not vibrate heavily. To closely cover
these vibration excitation sources corresponding
measurements are performed. The results, however,
are not subject to the HC-rating.
The influence of external sources on the wellbeing of
the crew is not considered. However, it is pointed out
that loading/unloading of the vessel herself as well as
harbour activities in general may substantially impair
the recreation of the crew.
2.
Requirements regarding acoustic privacy are given
in addition to those for noise and vibration. The ship should
be designed in a way that the acoustic privacy levels stated
in Table 2.2 are maintained. Noise measurements will be
conducted only in case complaints from the crew occur.
3.
The ship should be designed in a way that the
speech interference levels (SIL) maintain the limits given
in footnote of Table 2.1. Noise measurements will be
conducted only in case complaints from the crew occur.
4.
The personal noise protection has to be conform to Chapter 5 "Noise exposure limits" and Chapter 7 "Ear protection and warning information" of
IMO resolution A.468 (XII), 1982.
5.
Noise limits given are valid for Sea Mode
and under loading/unloading condition, vibration
limits are valid for Sea Mode only.
6.
The noise and vibration limits given for Sea Mode
Operation form an upper bound for any operation mode.
2.
The noise limit values depending on the harmony category number (hc) are listed in Tables 2.1 and 2.2.
3.
The noise measurement procedures are described in Section 3.
4.
Following tolerances may be applied in comparing the measured noise levels with the limit values.
4.1
Sea Mode and loading/unloading condition
4.1.1
Machinery, work, service and navigating
spaces
In case that the HC-criterion (Table 2.1) is exceeded
by max. 1 dB, this will be tolerated as long as the
corresponding Noise Rating curve (NR) is maintained.
4.1.2
Accommodation spaces
For day and sleeping rooms the average noise level per
deck is to comply with the limits of Table 2.1 provided
that not more than 15 % per deck exceed the relevant
HC-criterion and by not more than 2 dB(A) each.
For mess and recreation rooms as well as offices exceedances are not granted in any case.
4.1.3
Other spaces
Noise levels higher than specified for hospital, treatment room, corridors, open recreation deck, gymnasium, hobby room, indoor swimming hall, sauna etc.
are acceptable as long as not more than 30 per cent of
these spaces exceed the relevant HC-criterion and by
not more than 2 dB(A) each. IMO Res. A.468 (XII)
has to be fulfilled in any case.
4.2
Acoustic privacy
7.
Different requirements are valid for ships with
deck houses positioned aft and more forward, where
"aft position" is defined by a distance of the propeller
plane to aft deckhouse bulkhead < 20 % Lpp. All other
cases correspond to a "forward position".
Verification of acoustic privacy has to be proved either with a certificate (Rw-value) by the supplier of
interior systems combined with a site inspection or by
measurements. Taking sound flanking paths into consideration the certified Rw-value shall be 5 dB higher
than the specified limits in Table 2.2.
8.
Noise and vibration caused by charging or discharging of the vessel are not subject to these rules as such
operation is not practicable within the scope of sea trials.
C.
B.
Noise Limits and Tolerances
1.
Most relevant standards are ISO 2923, ISO
717/1, ISO 717/2 and IMO Resolution A.468 (XII).
Vibration Limits and Tolerances
1.
The most relevant vibration standard is ISO
6954, edition 2000. The limit values refer, consequently, to the overall frequency-weighted rms value
in the range of 1 to 80 Hz. The vibration velocities are
given in mm/s.
Chapter 23
Page 2–2
Section 2
C
Noise and Vibration Limits
2.
Required vibration limit values depending on
the harmony category (hc) are listed in Table 2.3.
3.
The vibration measurement procedure is described in Section 3.
4.
Following tolerances may be applied in comparing the measured vibration levels with the limit values.
Table 2.1
I - Part 1
GL 2009
4.1
No tolerance is granted for global longitudinal and transverse measurement points on decks forming the floor of living, working or recreation spaces.
4.2
Maximum 15% of all vertical measurement
points on floors in living, working or recreation spaces
may exceed the limit value given for the respective
target-hc by max. 0,3 mm/s.
Noise limits, crew accommodation and work spaces
Maximum noise level in dB(A)
DH aft position (see A.7.)
DH forward position
Sea mode and loading/
unloading operation 1
Sea mode and loading/
unloading operation 1
HC
HC
1
2
3
1
2
3
85
90
90
85
90
90
108
110
110
108
110
110
82
85
85
80
85
82
85
85
80
85
Machinery and work spaces
Machinery spaces (continuously manned) 1, 2
Machinery spaces (not continuously
manned) 1, 2
Workshops 1, 2, 5
Crane indoor working places (cockpit)
Laundries and changing rooms 1
Open deck working areas and rescue stations 2, 3, 4, 5
85
Control rooms located in and/or adjacent to engine rooms 1, 3
On car decks of RoRo and RoPax
Stores and work spaces not
vessels 2, 5
85
70
73
75
70
73
75
85
90
90
85
90
90
specified 2
90
90
Service spaces
Galleys 1, 5
70
73
75
70
73
75
Pantries, shops, etc. 1, 5
70
70
75
70
70
75
65
65
62
65
65
Navigation spaces
Navigation bridge and chart
rooms 1, 3
62
Radio rooms 1, 3
Listing posts, including outdoor bridge wings 6
60
60
70
70
Accommodation spaces
Day and sleeping rooms 1
mess 1, 3
rooms 1, 3,
offices 1
55
58
60
52
56
60
60
63
65
57
60
65
Gymnasiums, hobby rooms, indoor swimming halls, saunas etc. 1
65
70
70
60
65
70
Hospital 1
57
60
60
57
60
60
72
65
67
75
72
65
67
75
75
Crew's and officer's
and recreation
Treatment rooms 1
Corridors adjacent to accommodation spaces
Open deck recreation areas
75
1
The noise level generated only by air-conditioning and/or mechanical ventilation systems are to be limited to at least 7 dB(A) below the
required HC noise limit value.
2
Reference is made to COLREG, Annex II and IMO Resolution A.468 (XII), 1982 – ear protectors should be worn when the noise level is
above 85 dB(A).
3
For spaces requiring verbal communication when berthing the ship and during normal seagoing condition of the vessel (wheelhouse,
control rooms, mess and recreation rooms) the corresponding SIL level is to be maintained on board. Acceptance measurements are to be
conducted on board only in case that complaint of the crew occurs. The corresponding SIL level is determined as follow: SIL = (HC Noise
limit) minus 7 dB.
4
Open deck working spaces which are normally occupied during loading and discharging of the vessel are included, e.g. between container
cells, refrigerating containers, at pump stations, etc. (see also Annex B).
5
With mechanical ventilation in normal operation.
6
Reference is made to IMO Resolution A.343 (IX), 1975 – which also requires that the noise level at ¾ of max. vessel’s speed does not
exceed 68 dB in the 1/1 octave band at 250 Hz and does not exceed 63 dB in the 1/1 octave band at 500 Hz.
I - Part 1
GL 2009
Section 2
Noise and Vibration Limits
Table 2.2
Noise limits for acoustic privacy
C
Chapter 23
Page 2–3
On board acoustic privacy – sound insulation
(minimum required weighted apparent sound insulation index in dB
according to ISO 717/1 and ISO 140/4)
HC
Arrangements
1
2
Cabin to cabin 1
35
Cabin to mess and recreation rooms 1
45
Cabin to hospitals, gymnasiums, service spaces etc. 1
45
3
On board acoustic privacy – impact sound insulation
(maximum permissible normalized sound pressure level in dB
according to ISO 717/2, ISO 140/7)
HC
Arrangements
1
Cabin below and/or adjacent to gymnasiums, passageways on open
Cabin below bridge wings and
3
58
wheelhouse 1
Cabin below service spaces (galleys, pantries
1
2
deck 1
60
etc.) 1
65
Acoustic privacy levels are to be maintained on board. Acceptance measurements are to be conducted only in case that complaint of the
crew occurs.
Table 2.3
Vibration level limits
Vibration level limits in mm/s
(overall frequency- weighted rms value 1 to 80 Hz)
Day & sleeping rooms, hospital
DH aft position (see A.7.)
DH fwd position
HC
HC
1
2
3
Accommodation and recreation spaces
2,7
3,0
3,2
1
2
3
2,2
2,7
3,2
Mess and recreation rooms
3,0
3,3
3,5
2,5
3,0
3,5
Gymnasium
3,5
3,8
4,0
3,0
3,5
4,0
Open deck recreation areas
4,0
4,8
5,0
3,0
4,0
5,0
Work and nav. spaces, permanently manned
Nav. bridge, chart & radio room
3,5
3,8
4,0
3,0
3,5
4,0
Engine control room
3,5
4,0
4,5
4,0
4,3
4,5
Galley
4,0
4,3
4,5
3,5
4,0
4,5
Offices
3,5
3,8
4,0
3,0
3,5
4,0
Work and nav. spaces, sometimes manned
4,0
4,3
4,5
3,5
4,0
4,5
Offices
Navigation bridge wing
5,0
5,3
5,5
4,5
5,0
5,5
Workshops
5,0
5,0
5,0
5,0
5,0
5,0
Spaces, not manned
6,0
6,0
6,0
6,0
6,0
6,0
6,0
6,0
6,0
6,0
Machinery spaces
Stores
6,0
6,0
I - Part 1
GL 2009
Section 3
C
Required Measurements
Chapter 23
Page 3–1
Section 3
Required Measurements
C.
Performance of Measurements
1.
Noise and vibration measurements and their
evaluation have to be carried out by GL experts or
companies accepted by GL.
1.
Noise
1.1
Instrumentation
2.
Propulsion machinery power shall be verified
during measurements.
The measuring instrumentation has to fulfil the requirement according to ISO 2923. Basically an integrating sound level meter with 1/3-octave filters shall
be applied.
A.
General
3.
Measurements shall be witnessed by a GL
expert.
A measuring device suitable for storing time signals,
sound (booming) or obvious tonal components is to be
provided.
B.
Measuring Conditions
1.2
1.
Sea Mode
The measurement locations have to be chosen according to ISO 2923. All measurement positions shall be
documented traceable in a measurement location plan.
1.1
Propulsion machinery shall produce the necessary power to reach the service speed of the vessel
as contractually agreed on. Power shall not be less
than 85 % MCR.
1.2
The minimum water depth during measurements shall be at least five times the aft draught. For
ships normally operating in shallow waters, corresponding conditions have to be chosen for measurements.
1.3
Sea state 3 (significant wave height approx.
1,2 m) and a wind speed of 4 Bft shall not be exceeded. For more severe weather conditions, the acceptance of measurements will be decided by GL on a
case-by-case basis.
1.4
The course of the vessel shall be as straight as
possible. Minimum rudder movement is imperative.
Rudder angles shall not exceed ± 2 degrees.
1.3
Measurement locations
Measurement procedure
The general measurement procedure is described in
ISO 2923.
During each measurement, the microphone is to be
slowly moved horizontally and/or vertically over a
distance of approximately ± 0,5 m (averaging over
time and space).
Wind noise, e.g. wind trash, singing or similar effects
have to be reported for outdoor spaces surveyed.
The overall sound pressure level (LAeq), file number
of the data storage (ID number), measurement location, noise limit according to hc target and subjective
noise impression are to be recorded and immediately
noted in measurement protocol sheets after recording.
1.3.1
Acoustic privacy
1.5
The ship shall be fully outfitted, and all systems contributing to noise and vibration shall be in
normal seagoing condition, i.e. all auxiliary machinery, navigation instruments, radar sets, etc. shall be in
normal operation.
Acoustic privacy measurements shall be carried out if:
Mechanical ventilation and air-conditioning equipment shall be in normal operation (capacity to be in
accordance with design conditions). All air-conditioning systems shall be adjusted prior to measurements.
1.6
Doors and windows shall, in general, be
closed.
–
no adequate certificate is available
–
proper workmanship during outfitting is not
approved
–
the sound or impact insulation keeps obviously
not the limits (subjective impressions) or complaints occur
Required measurements shall be performed following
the standards ISO 140/4, ISO 140/7, ISO 717/1 and
ISO 717/2.
Chapter 23
Page 3–2
1.3.2
Section 3
C
Required Measurements
I - Part 1
GL 2009
Presence of secondary noise sources
2.
Vibration
In general, secondary noise sources (e.g. rattling,
knocking and squeaking noises from doors, panels,
furniture, fittings or fixtures etc.) are to be eliminated
in crew accommodation space.
2.1
Instrumentation
1.3.3
Presence of obvious tonal components
1.3.3.1 In general, obvious tonal components in crew
accommodation spaces will not be accepted for Sea
Mode or Harbour Mode. Obvious tonal components
audible in crew spaces are to be subjectively judged
and reported.
1.3.3.2 If measured noise contains obviously tonal
components, third-octave band readings are to be
taken and stored, with centre frequencies from 20 Hz
to 10 kHz. In addition, narrow band readings should
be measured and stored in the frequency range of
interest.
1.3.3.3 The octave band levels in dB are to be calculated based on the third-octave band measurements as
described in 1.3.4.2. The octave band levels in dB are
to be compared against the corresponding NR curves.
1.3.4
Presence of booming effects
1.3.4.1 In general, the presence of annoying lowfrequency sound (booming effects) occurring in crew
spaces during Sea or Harbour Mode will not be accepted. Annoying low-frequency sound audible in
crew spaces are to be subjectively judged and reported.
2.1.1
The equipment shall be calibrated at periodic
intervals of not more than two years. Calibration
sheets shall be provided.
2.1.2
On non-magnetic floors, measuring sensors
should preferably be mounted on a three-legged plate
with a minimum weight of 1500 g.
2.1.3
The instrumentation shall allow for calculation of the weighted rms value in terms of vibration
velocity according to ISO 6954.
2.1.4
Provision shall be made for the storage of all
spectra and a limited number of time records.
2.1.5
The instrumentation shall comply with requirements of ISO 8041.
2.2
Measurement Locations and Directions
2.2.1
The required number of measurement locations depends on the vibration direction to be measured (longitudinal, transverse or vertical).
2.2.2
Measurement locations for assessing longitudinal vibrations shall be chosen in a way that measurement results adequately reflect the global longitudinal deck house vibration level. At least following
positions should be included:
–
weather deck level , deckhouse front wall, ps or
sb
1.3.4.2 Where the measured noise levels contain
annoying low-frequency sound (booming effects),
third-octave band readings are to be taken and stored,
with centre frequencies from 20 Hz to 10 kHz. In
addition, narrow band readings should be measured
and stored in the frequency range of interest.
–
nav. deck level in way of ps and sb deckhouse
walls
–
nav. deck level outer edge of ps or sb bridge
wing
–
compass deck level, main mast foundation
1.3.4.3 The octave band levels in dB are to be calculated based on the third-octave band measurements as
described in 1.3.5.2. The octave band levels in dB are
to be compared against the corresponding NR curves.
–
top of main mast
1.3.5
Presence of impulse noise
1.3.5.1 In general, impulse noise in crew spaces will
not be accepted for Sea or Harbour Mode Impulse
noise audible in crew spaces are to be reported.
1.3.5.2 Impulse noise is to be determined following
the procedure described in ISO 2923.
1.3.6
SIL-Levels
SIL-levels mentioned in Section 2, Table 2.1 footnote 3 are to be calculated by arithmetic averaging the
octave-band levels 500 Hz, 1000 Hz, 2000 Hz and
4000 Hz.
2.2.3
Measurement positions for assessing transverse vibration shall be chosen in a way that results
adequately reflect the global transverse hull and deckhouse vibration level. At least following measurement
positions should be included:
–
weather deck level, transom ps or sb
–
weather deck level , deckhouse front wall ps or sb
–
nav. deck level, in way of aft and front deckhouse walls
–
compass deck level, main mast foundation
–
top of main mast.
2.2.4
Measurement positions for assessing vertical
vibration shall be chosen in a way that results adequately reflect local vibration levels of deck panels in
I - Part 1
GL 2009
Section 3
D
Required Measurements
accommodation and working spaces. At least following measurement positions should be included:
–
all crew and, if present, passenger cabins. For combined living and sleeping rooms one position, for
separate rooms two measurement positions
–
all working, navigation, accommodation spaces
and offices which are permanently or frequently
occupied
–
inner and outer deck recreation spaces
–
nav. deck level outer edge of ps or sb bridge
wing
–
sample measurements in non-occupied spaces as
machinery rooms and stores.
–
compass deck level, main mast foundation
2.3
Measurement procedure
2.3.1
Provision shall be made that amplitude spectra of the measured time signals can be made available
during sea trials for diagnostic purposes, i.e. identification of frequency content.
2.3.2
If desired by GL experts, for instance if beating occurs, time records of selected measurement
positions shall be recorded and stored.
2.3.3
To ensure comparability of the spectra, the
following parameters shall be applied for data acquisition and signal processing:
–
measurement time per point: ≥ 1 min
–
sampling rate: ≥ 300 1/s
Chapter 23
Page 3–3
–
spectral frequency range: 1 Hz to 80 Hz
–
minimum spectral resolution: 0,2 Hz
–
FFT window function: flat top (if not available,
Hanning window)
–
FFT averaging mode: linear averaging (stable
mean)
2.3.4
The results shall be presented as weighted
rms values in terms of vibration velocity
D.
Preparation and Documentation of Measurements
1.
Survey Programme
Measurements shall be planned in due time before
conducting the measurements, be documented in a
Survey Programme containing all relevant information. The Survey Programme has to be submitted to
GL at least two months before sea trials or measurements.
2.
Survey Report
The measurement results as well as the resulting HCClass Notation shall be documented in a report based
on the Survey Program. Each deviation from the Programme shall be explicitly stated.
An electronic standard form containing all information
to be filled in can be submitted on request.
I - Part 1
GL 2009
Annex A
B
Standards
Chapter 23
Page A–1
Annex A
Standards
A.
Field measurements of airborne sound insulation
between rooms"
General
1.
If these Rules contain procedures deviating
from the relevant standards, these Rules shall have
priority.
B.
Standards
1.
Noise standards
–
IMO Resolution A.468 (XII): 1982,
"Code on noise levels on board ship"
–
IMO Resolution A.343 (IX): 1975-11,
"Recommendation on Methods of Measuring
Noise Levels at Listening Posts"
–
ISO 2923, 1996-12,
"Acoustics – Measurement of noise on board
vessels"
–
ISO 31-7: 1992-09,
"Quantities and units of acoustics"
–
IEC 61672 / 2003-10,
"Electroacoustics - Sound level meters - Part 1:
Specifications"
–
ISO 140/6: 1978-07,
"Acoustics – Measurement of sound insulation
in buildings and of building elements – Part 4:
Laboratory measurements of impact sound insulation of floors",
here: “4 Equipment….tapping machines with
rubber coated hammers…”
–
ISO 140/7: 1998-12,
"Acoustics – Measurement of sound insulation
in buildings and of building elements – Part 7:
Field measurements of impact sound insulation
of floors"
–
ISO 9921: 2003/10,
"Ergonomics – Assessment of speech communication"
–
ISO 1999: 1990-01,
"Acoustics – Determination of occupational
noise exposure and estimation of noise-induced
hearing impairment"
2.
Vibration standards
–
IEC 61260: 1995-08 and IEC 61260-Am 1:
2001-09,
"Electroacoustics - Octave-band and fractionaloctave-band filters"
–
ISO 6954: 2000E, "Mechanical vibration –
Guidelines for the measurement, reporting and
evaluation of vibration with regard to habitability on passenger and merchant ships"
–
IEC 60942: 2003-11,
"Sound calibrators"
–
–
ISO/DIS 20283-3: 2005,
"Pre-installation vibratory noise measurement of
shipboard equipment"
ISO 2631-1: 1997 (E), "Mechanical vibration
and shock – Evaluation of human exposure to
whole-body vibration – Part 1: General requirements"
–
ISO 2631-2: 1989 (E), "Mechanical vibration and
shock – Evaluation of human exposure to wholebody vibration – Part 2: Continuous and shock
induced vibration in buildings (1 - 80 Hz)"
–
ISO 4867: 1984 (E), "Code for the measurement
and reporting of shipboard vibration data"
–
ISO 4868: 1984 (E), "Code for the measurement
and reporting of local vibration data of ship
structures and equipment"
–
ISO 8041: 1990 (E), "Human response to vibration – Measuring instrumentation"
–
GL
–
ISO 717/1: 1996-12,
"Acoustics – Rating of sound insulation in
buildings and of building elements – Part 1:
Airborne sound insulation in buildings and interior elements"
–
ISO 717/2: 1996-12,
"Acoustics – Rating of sound insulation in
buildings and of building elements – Part 2: Impact sound insulation"
–
ISO 140/4: 1998-12,
"Acoustics – Measurement of sound insulation
in buildings and of building elements – Part 4:
Rules
Machinery
Installations
(I-1-2)
I - Part 1
GL 2009
Annex B
A
Important Definitions
Chapter 23
Page B–1
Annex B
Important Definitions
1.
Angular frequency, circular frequency
ω [rad/s] is the product of the frequency of a sinusoidal quantity and the factor 2 π:
ω = 2π ⋅ f
2.
Acoustic privacy
"Privacy" from an acoustical point of view, i.e. the
state of being alone and relatively undisturbed with
regard to noise emissions from neighbouring cabins,
sanitary cells, corridors, public spaces, open deck
recreation spaces, service spaces etc. (sound and impact sound insulation).
3.
Acoustic privacy plan
Drawings showing the arrangement of all cabin types
including noise limit values to be kept. See also "cabin
type".
4.
Auxiliary machinery
Machinery, other than main propulsion machinery,
operating when the ship is in normal service, e.g.
auxiliary diesel engines, turbo-generators, hydraulic
motors and pumps, compressors, boilers, ventilation
fans, gears, pumps.
5.
Abatement measures
Noise and/or vibration control measures, e.g. with the
aim of reducing the airborne and/or structure-borne
noise emission as well as of vibration levels of structures, equipment etc.
6.
A-weighted sound pressure level LAeq or
LAeq,T
The A-weighted equivalent continuous sound pressure
level using the frequency weighting "A" as specified
in the IEC publication 60651 within a measurement
time interval T.
7.
Beat, beating
Periodic amplitude variations of an oscillation resulting from the superposition of two excitation sources of
slightly different frequencies. Beating which occurs in
the audible frequency range is experienced as being
annoying.
8.
Boom, booming
Deep, hollow resonant low-frequency sound in the
range between 16 and 125 Hz. Booming is mainly due
to one or more discrete tonal components of significantly greater amplitudes than those of the adjacent
spectrum level. Booming is experienced as being
annoying and can only be detected subjectively. See
also "steady noise with audible discrete tones".
9.
Booming rating procedure
Procedure for measuring and assessing the occurrence
of audible discrete tones below 125 Hz (booming
effect). The procedure developed by GL is based on
experimental investigations on board ships.
As result of this procedure a booming adjustment (CB
in dB(A)) is established. The noise rating level has to
be used for further evaluation.
10.
Cabin type
Cabins with different types of interior systems (lining
walls, ceilings, doors, etc.), floor constructions, floor
coverings etc. See also "Acoustic Privacy Plan".
11.
Crew spaces
Cabins, offices (for carrying out the ship's business),
hospitals, mess rooms, recreation rooms (such as
lounges, smoke rooms, cinemas, libraries, hobby and
game rooms) and open recreation areas used by officers and crew.
12.
Corridors
Passageways/alleyways arranged in crew and passenger spaces.
13.
Displacement (Δ)
Displacement of the vessel in metric tonnes.
14.
Engine or shaft speed
Number of revolutions per minute [rpm]
15.
Equivalent continuous sound pressure
level Leq or Leq,T
Unweighted sound pressure level of a continuous
steady sound. Within a measurement time interval T
this sound has the same mean square sound pressure
as a sound under consideration that varies with time. It
is expressed in decibels by the following equation:
Chapter 23
Page B–2
Annex B
A
Important Definitions
2
⎡
⎤
t2 ⎛ p ( t) ⎞
1
Leq = Leq ,T = 10 log10 ⎢
⎟⎟ ⋅ dt⎥
∫ ⎜⎜
⎢( t2 − t1 ) t1 ⎝ po ⎠
⎥
⎣
⎦
I - Part 1
GL 2009
23.
Measured SPL
where:
The sound pressure level measured with a sound level
meter or sound measurement instrumentation. The
measured SPL shall be expressed to one decimal
place.
(t2 – t1) = is the period T over which the average is
taken, starting at t1 and ending at t2
24.
p (t)
= unweighted instantaneous rms sound pressure between 16 and 16 000 Hz
See "A-weighted sound pressure level".
p0
= 2 ⋅ 10–5 Pa (reference level)
25.
16.
Fluctuating noise
The measured sound pressure level (e.g. pointer of the
display) varies more than ± 3 decibels with the "slow"
meter characteristic switched on. Impulse noise shall
be excluded.
17.
HVAC
Heating, venting and air-conditioning system
18.
19.
26.
The noise rating level LA, r is defined as follows:
L A, r = L Aeq + CT + CI + CB in dB(A)
LA, r
is the noise rating level in dB(A)
LAeq
is the measured overall A-weighted sound
pressure level
CT, CI, CB are adjustments as result of the tone, impulse and booming rating procedure
27.
28.
Overall frequency-weighted rms value
The overall frequency-weighted rms value has to be
determined according to ISO 6954.
29.
Machinery spaces
Maximum continuous rating (MCR)
Designed maximum continuous power rating of main
engines.
RMS value
The rms value of a single-valued function, f(t), over an
interval between t1 and t2 is
12
ISO noise rating (NR) number
All spaces containing propulsion machinery, boilers,
steam and internal combustion engines, generators and
major electrical machinery, oil filling stations, refrigerating, stabilizing, hydraulic units, air-conditioning
cooling compressors, etc.
22.
Normal service speed
Shaft speed and propulsion power corresponding to
service speed contractually agreed on, at least at 85 %
MCR.
⎡ t2
⎤
2
⎢ ∫ t1 f ( t ) dt ⎥
rms value = ⎢
⎥
⎢ t 2 − t1 ⎥
⎣⎢
⎦⎥
The number found by plotting the 1/1 octave band
spectrum of the NR curves given in ISO Standard R
1996-1967 and selecting the highest noise rating curve
tangent to the spectrum .
21.
Noise rating level
Integrating sound level meter
A sound level meter designed or adapted to measure
the level of the mean squared time averaged Aweighted sound pressure level (IEC 804).
20.
NRC
Noise rating curve, see "ISO noise rating (NR) number".
Impulse noise
Noise of less than one second duration that occurs as
an isolated event or as one of a series of events with a
repetition rate of less than 15 times per second. The
presence of impulse noise shall be determined by
obtaining the difference between the equivalent continuous sound pressure level measured with time
weighting "impulse" and "fast". If the difference is
more than 2 dB, the presence of impulse noise may be
assumed. As result of this GL procedure an impulse
adjustment (CI in dB(A)) is established. The noise
rating level has to be used for further evaluation.
Noise level
30.
Room space
Total room area of an individual public space in
square metres.
31.
Sound pressure level "L"
A measure of sound level on logarithmic scale given
by:
⎛ p ⎞
L = 20 log10 ⎜ ⎟ [ dB]
⎝ p0 ⎠
I - Part 1
GL 2009
Annex B
A
Important Definitions
Chapter 23
Page B–3
where:
34.
p
= rms value of measured sound pressure between 16 and 16 000 Hz
p0
= 2 ⋅ 10–5 Pa reference level
A sound wave whose instantaneous sound pressure
varies essentially as a simple sinusoidal function of
time (pure tone). Tonality is experienced as being
annoying and can only be detected subjectively. Tonality is defined in the frequency range between
125 and 16 000 Hz. It is mainly caused by main reduction gears, pumps, air-conditioning cooling compressor units, thruster gears, HVAC inlet and outlet openings etc.
32.
Steady noise without audible discrete tones
Level fluctuations equal to or less than ± 3 decibels. This
type of noise is frequently referred to as "broad-band"
noise. Obvious tonal components of noise (tonality and/
or booming) in the whole audible frequency range between 16 and 16 000 Hz are absent or negligibly small.
33.
Steady noise with audible discrete tones
This type of noise has components at one or more
discrete frequencies having significantly greater amplitudes than those of the adjacent spectrum level.
Audible discrete tonal components of noise (tonality
and/or booming) can occur in the whole audible frequency range between 16 and 16 000 Hz.
35.
Tonality, annoying discrete tone
Tone rating procedure
Procedure for measuring and evaluating the occurrence of tonality. It is described in DIN 45681 "Determination of tonal components of noise and determination of a tone adjustment for the assessment of noise
immissions"
As a result of this procedure, a tone adjustment (CT in
dB(A)) is established. The noise rating level has to be
used
for
further
evaluation.
I - Part 1
GL 2009
Annex C
D
Recommendations to Reduce Noise and Vibration
Chapter 23
Page C–1
Annex C
Recommendations to Reduce Noise and Vibration
A.
General
To maintain the required noise and vibration levels
various investigations and reduction measures are
recommended. This concerns the planning, design,
fabrication and testing phase of a newbuilding.
B.
Considerations Regarding Excitation Forces
By nature, the reduction of noise and vibration excitation forces is the most effective way to reduce the
noise and vibration levels. Therefore it is recommended:
–
to optimise the ship's lines by model tests in
order to achieve an appropriate wake distribution
–
to optimise the propeller design with regard to
noise and vibration excitation by cavitation tank
tests
–
to take into account the noise and vibration
excitation characteristics of main and auxiliary
machinery, gear, bow thruster etc. by appropriate choice of suppliers
C.
Theoretical Investigations
1.
Noise and vibration aspects should be considered as early as possible in the design process.
2.
The extent of the theoretical investigations
necessary depends on the experience of the yard with
the relevant ship type. As a guideline the analyses
summarised in Table C.1 are recommended.
The following types of investigations are distinguished:
2.1
Review of general arrangement plan
Prior to detailed investigations, the general arrangement plan is reviewed with regard to noise and vibration. This should take place as early as possible in the
design process.
2.2
Local vibration calculation
Natural frequencies of plate fields, stiffeners and small
regularly stiffened panels are estimated by means of
empirical formulas. The objective is to avoid resonance with main excitation frequencies. Added masses
as well as hydrodynamic masses have to be considered. Attention should focus on deck structures situated in the deckhouse and on living and working
spaces close to the propeller and main engine. Natural
frequencies of all structural components shall be chosen to have a sufficient margin to main excitation
frequencies.
2.3
Noise prediction
A noise prediction is conducted at an early design
stage. Semi-empirical noise prediction programmes
are applied to predict the average airborne noise levels. Noise limits specified for passenger and crew
spaces are compared with predicted values.
2.4
Global vibration level prediction
In a global vibration level prediction, the vibration
level at "global" points of the ship structure is estimated on the basis of a forced vibration calculation in
the lower frequency range (~ 1 Hz to 20 Hz). Dynamic
magnification due to local resonances of plate fields,
stiffeners or panels is not considered. These local
structural systems are investigated separately (see
‘Local Vibration Calculation’).
The vibration level is estimated for relevant loading
conditions at representative points of the ship structure.
If the predicted vibration levels are expected to exceed
the specified limits, modifications of the steel structure, a different number of propeller blades, arrangement of compensators, etc. might be proposed as possible means of improvement.
D.
Secondary Measures
If the theoretical investigations reveal that the required
noise and vibration levels probably can not be maintained secondary measures should be provided, i.e.
–
isolation (resilient supports for instance)
–
insulation, encapsulation
–
damping (floating floors for instance)
–
compensation of vibration excitation forces
–
silencing
–
structural modifications
Chapter 23
Page C–2
E.
Annex C
E
Recommendations to Reduce Noise and Vibration
Supplementary Measurements during
Production Phase
1.
It is recommended to carry out test bed noise
and vibration measurements for machinery components in order to check the adherence to noise specifications agreed on with suppliers.
Table C.1
I - Part 1
GL 2009
2.
During outfitting stage the local vibrations of
deck structures should be measured (impact or/and exciter measurements) to verify calculation results and to
identify and rectify local structural deficiencies.
3.
During outfitting stage the impedance of machinery foundations should be measured to verify calculation results and to identify and rectify local structural deficiencies.
Recommended theoretical investigations for seagoing cargo vessels
Deckhouse position
forward
Deckhouse position
aft
hc
hc
1
2
3
1
2
3
Review of general arrangement
O
O
O
O
O
O
Local vibration calculation
O
O
O
O
O
O
Noise prediction
Z
Z
Z
O
O
O
Global vibration level prediction
P
P
P
Z
Z
Z
O = Strongly recommended
Z
= Recommended
P = Recommended only if experience with similar ships is not available