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SECTION 2 COMFORTWITH REGARDTO VIBRATIONS

1 General

1.1 Application

1.1.1 Application

The notation COMF-VIB, in accordance with Pt A, Ch 1,Sec 2, [6.7.3], will be granted to ships complying with therequirements of this section.

1.1.2 Ship categories

The ships are divided into three main categories, taking intoconsideration the specifics of the ship in the vibration field,

and the technical feasibility for the ship to comply withthese rules at a reasonable cost:

a) Ships with length between perpendiculars below 65 m,including fishing ships, tug boats, ferries, little passengerships, etc., for which the unavoidable proximity of thesources, makes necessary special measures for vibrationreduction.

b) Passengers ships, including cruise ships, ferries and lin-ers, in which comfort needs particular care.

c) Heavy duty ships, namely all types of cargo ships,including tankers, container ships, bulk carriers, etc.where a minimum comfort is necessary to prevent

human errors due to excessive stress of the crew.

1.1.3 Exclusions

a) These rules apply to open and closed spaces in the crewand passenger living and transfer areas. They do notapply to machinery spaces or garages.

b) These rules are not applicable to public restrooms orlaundries.

1.1.4 Merit levels

Three decreasing merit levels, A, B, C, are possible. Thenotation is assigned if at least the C merit level is reached.

1.2 Basic principles1.2.1 Scope of the rules

These rules define the limits and criteria of acceptability ofvibration levels on board. They indicate the internationalreference standards, procedures and instrumentation neces-sary to carry out the measurements.

1.2.2 Assessment criteria

The criteria considered for the assessment of personal com-fort are based on the evaluation of vibration levels duringnormal navigation. These rules do not consider the effectsof ship motions.

1.2.3 International standards

These rules are based on the most recent internationalstandards and requirements relevant to the measurementand control of vibration issued by ISO. Sec 1, Tab 1 liststhese standards:

Table 1

1.2.4 Compliance with the rules

Compliance with these rules is verified by means of meas-urements to be carried out on board in the conditions andlocations indicated.

1.2.5 Measurements

Measurements are to be carried out by either a SocietysSurveyor or by a technician from a company recognised assuitable by the Society. In the latter case, measurements areto be carried out under the surveillance of the Surveyor.

1.3 Definitions

1.3.1 Crew accommodation

Crew accommodation are cabins, offices, hospitals, messrooms recreation rooms and open deck areas to be used bythe ship officers and crew.

1.3.2 Passenger accommodationsPassenger accommodations are all open and closed areasintended to be used by the passengers.

1.3.3 Public spaces

a) Public spaces are all the spaces allocated to passengersincluding public spaces for prolonged and/or recrea-tional stay, enclosed spaces for non prolonged passen-ger stay and outside spaces for prolonged and/orrecreational stay.

b) Garages, laundries, public restrooms, corridors andstairs are not considered as part of this definition.

c) As far as these rules are concerned, the following defini-tions of enclosed public spaces are used:

1) Type A recreational spaces:

Enclosed spaces for either passenger recreationand/or prolonged passenger stay where the noise

Standard Number Title

ISO 2041 Vibration and shock - Vocabu-lary

ISO 2631 Guide for the evaluation of human exposure to whole-bodyvibration

ISO 4867 Code for the measurements andreporting of shipboard vibration

dataISO 4868 Code for the measurements and

reporting of local vibration dataof ship structures and equipment

ISO 6954 Mechanical vibration and shock- Guidelines for the overall eval-uation of vibration in merchantships

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level is normally high when in use (discos, cinemas,gaming rooms, etc.)

2) Type B recreational spaces:

Enclosed spaces for either passenger recreationand/or prolonged passenger stay where the noise

level is not normally high when in use (restaurants,bars, gymnasium, conference halls, theatres, casi-nos, lounges, etc.)

3) Type C recreational spaces:

Enclosed spaces for either passenger recreationand/or prolonged passenger stay where the noiselevel is to be low (reading rooms, libraries, cardrooms, chapels, etc.)

4) Type D spaces:

Spaces where passengers are not normally expectedto stay long (shops, enclosed walkways, halls, corri-

dors, etc.).

1.3.4 Passenger cabins, suites and mini-suites

Passenger cabins, suites and mini-suites are small spaces forprivate use of the passengers.

1.3.5 Vibration

a) Time variation of the value of a physical quantitydescribed by either the motion or the position of amechanical system when this value is alternativelygreater or smaller than a mean reference value.

b) As far as these rules are concerned, the physical quan-tity for reference is the structural velocity, measured inmm/s, in the frequency range from 1 to 100 Hz.

1.4 Documentation to be submitted

1.4.1 Measurement plan

a) In order to obtain the notation, measurements of vibra-tion levels are to be taken as indicated in Sec 1, [4].

b) A detailed measurement campaign plan is to be submit-ted, in order to assess preliminary compliance withthese rules.

c) The plan is to include extension and classification of

ship zones, minimum number of measurements to betaken in each ship space concerned, and position ofmain vibration sources.

1.4.2 Reporting of results

a) Following the measurements campaign, as per Sec 1,[4], a detailed report is to be submitted. The formsshown in [4]may be used for this purpose.

b) The report is to contain:

position of measurement points

measured vibration levels

resulting comfort levels, assigned according toSec 1, [3.3.6] and Sec 1, [3.3.8]

global comfort levels resulting, according to Sec 1,[3.5]

c) The following general data and conditions are to berecorded and included in the report:

ship loading condition

propulsion machinery, main auxiliaries, navigationalaids, radio and radar sets

water depth

environmental conditions (wind and waves)

vibration sources due to external factors such aspresence of additional personnel, ongoing repairs orfitting work, etc.

2 Experimental test criteria

2.1 General

2.1.1

a) Vibration levels resulting from the functioning of shipsystems and equipment are to be measured without pas-sengers on board in the operating conditions defined inSec 1, [3.2].

b) Different conditions can be considered if accepted asequivalent for the purposes of these rules at the discre-tion of the Society.

2.2 Vibration levels: transit condition

2.2.1 Propulsion plant power

a) Measurements are to be carried out with propulsionplants working at 85% of maximum power.

b) Additional measurements are to be carried out with pro-pulsion plants at full power in particularly critical areas,i.e. areas whose vibration level measured is very closeto the limit given for the comfort level assigned and forwhich an appreciable rise in vibration intensity can beexpected (see Sec 1, [3.3.8] and [2.4.4]).

2.2.2 Auxiliaries

During measurements, all auxiliary systems, forced ventila-tion and air conditioning systems (HVAC systems) and hotelservice systems are to be operating in normal service condi-

tions.2.2.3 Human activity

a) During measurements, vibrations arising from everykind of unnecessary human activity are to be avoided.

b) For this purpose only the personnel needed for the nor-mal operation of the ship and those carrying out themeasurements are to be present and as far as possible astraight course is to be held.

2.2.4 Entertainment systems

During measurements every crew and passenger entertain-ment system is to be off.

2.2.5 Water depth

Water depth is to be sufficiently great, at least 10 timesmedium ship draught.

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2.2.6 Meteorological conditions

In general, meteorological conditions are to be within thefollowing limits:

wind: not stronger than Beaufort 3 - strong breeze(speed 7 to 10 knots),

waves: not stronger than force 3 - rough (significantwave height 0.5 to 1.25 m).

2.3 Vibration levels

2.3.1 Measurement positions

Measurements are to be carried out, in 50% of the spacesand with similar criteria as for the noise tests as described inSection 1. At the Societys discretion, additional measure-ments are to be carried out in particular locations within themeasurement area.

2.3.2 Limits

The vibration level is equal to the peak structural velocity,

measured in mm/s, recorded in the frequency range from 1to 100 Hz, as per ISO 6954 using a "conversion factor"equal to 1.0. For each space typology, limit curves for the

calculation of the vibration merit parameter are given in Fig1 and Tab 2. Tab 2 also shows the numerical limits for fre-quencies below 5 Hz.

Figure 1 : Limit curves for vibration levels

Table 2

Passenger ships Heavy cargo shipsShips with length below65m

SpacesMin/Max

curve

Vmin/Vmax(mm/s)

Min/Max

curve

Vmin/Vmax(mm/s)

Min/Max

curve

Vmin/Vmax(mm/s)

Suites or mini-suites C1 C2 1,5 2,5

Standard passenger cabins C1 C3 1,5 3,5 C3 C3 3,5 3,5

Type A recreational space C2 C4 2,5 4,0Type B recreational space C2 C4 2,5 4,0

Type C recreational space C2 C3 2,5 3,5

Type D recreational space C2 C4 2,5 4,0

Passenger outside recreationalspace

C2 C5 2,5 5,0 C3 C5 3,5 5,0

Public spaces C3 C4 3,5 4,0

Wheelhouse C2 C3 2,5 3,5 C2 C3 2,5 3,5 C3 C4 3,5 4,0

Radio room C2 C3 2,5 3,5 C2 C3 2,5 3,5

Crew cabins C2 C3 2,5 3,5 C2 C3 2,5 3,5 C3 C3 3,5 3,5

Offices C2 C3 2,5 3,5 C2 C3 2,5 3,5

Mess rooms C2 C4 2,5 4,0 C2 C4 2,4 4,0 C3 C4 3,5 4,0

Hospitals C1 C3 1,5 3,5 C2 C3 2,5 3,5

Engine control rooms C2 C3 2,5 3,5 C2 C3 2,5 3,5 C3 C4 3,5 4,0

Crew outside recreational space C3 C5 3,5 5,0 C3 C5 3,5 5,0

Stores C3 C4 3,5 4,0 C3 C4 3,5 4,0

Workshops C3 C4 3,5 4,0 C3 C5 3,5 5,0 C3 C5 3,5 5,0

Gangways, staircases and pas-sages in crew areas

C3 C4 3,5 4,0 C3 C4 3,5 4,0 C3 C5 3,5 5,0

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2.3.3 Comfort level - measurements at 85% of fullpropulsive power

For each measurement point, the measured vibration level,Vmis, is compared with Tab 2 limits.

a) Suites or mini-suites, passenger cabins and type A, B, C,

D spaces less than 120 m2

1) Comfort level is A if:

all Vmis values are less than or equal to Vmin, or

all Vmis values are less than or equal to Vmin,

except for less than 5% of values measured,which are to be less than Vmin + 0,5 mm/s

2) Comfort level is B if:

all Vmis values are less than Vmax

3) Comfort level is C if:

all Vmis values are less than or equal to Vmax,

except for less than 5% of values measuredwhich are to be less than Vmax + 0,5 mm/s.

b) Type A, B, C or D spaces greater than 120 m2, and otherclosed spaces

1) Comfort level is A if:

all Vmis values are less than or equal to Vmin, or

all Vmis values are less than or equal to Vmin,

except 20% of the total area, where Vmis is less

than or equal to Vmin + 0,5 mm/s

2) Comfort level is B if:

all Vmis values are less than or equal to Vmax

3) Comfort level is C if:

all Vmis values are less than or equal to vmax,

except 20% of the total area, where Vmis is lessthan or equal to Vmax + 0,5 mm/s.

c) Outside recreational spaces

1) Comfort level is A if:

all Vmis values are less than or equal to Vmin, or

all Vmis values are less than or equal to vmin,

except 30% of the total area, where Vmis is less

than or equal to Vmin +0,5 mm/s

2) Comfort level is B if:

all Vmis values are less than or equal to Vmax

3) Comfort level is C if:

all Vmis values are less than or equal to Vmaax,

except 30% of the total area, where Vmis is lessthan or equal to Vmax + 0,5 mm/s.

Fig 2, Fig 3 and Fig 4 are a graphic indication of the vari-ous noise limits for passenger ships, Fig 5 for heavy cargoships and Fig 6 for ships with length below 65 m.

Figure 2 : Passenger ships - Vibrations levels at 85% power - Table 1 of 2

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Figure 3 : Passenger ships - Vibrations levels at 85% power - Table 2 of 2

Figure 4 : Heavy cargo ships - Vibration levels at 85% power - Table 1 of 1

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Figure 5 : Ships with length below 65 m - Vibration levels at 85% power - Table 1 of 1

2.3.4 Measurements at full propulsive power

a) Additional measurements are to be taken in those posi-tions or spaces shown to be critical by measurementstaken according to 2.3.6, outside recreational spacesbeing excluded.

b) The total number of measurements taken at full propul-sive power is not to exceed 5% of the number of meas-urements taken at 85% of full propulsive power.

c) At the Societys discretion additional measurements areto be carried out in particular positions within testedareas.

d) For each point, the measured noise level, Vmis, is com-pared with Tab 2 limits.

2.3.5 Comfort level - measurements at fullpropulsive power

For each measurement point, the measured noise level, Lmis,

is compared with Sec 1, Tab 8limits.

a) Suites or mini-suites, passenger cabins and type A, B, C,

D spaces less than 120 m2

1) Comfort level is A if:

all Vmiss values are less than or equal to Vmin, or

all Vmis values are less than or equal to Vmin+ 0,3

mm/s, except for less than 5% of values meas-ured which are to be less than Vmin + 0,5 mm/s;

2) Comfort level is B if: all Vmis values are less than Vmax+ 0,3 mm/s

3) Comfort level is C if:

all Vmis values are less than or equal to Vmax+ 0,3

mm/s, except for less than 5% of values meas-ured which are to be less than Vmax + 0,5 mm/s.

b) Type A, B, C or D spaces greater than 120 m2, and otherenclosed spaces

1) Comfort level is A if:

all Vmis values are less than or equal to Vmin+ 0,3mm/s, or

all Vmis values are less than or equal to Vmin+ 0,3

mm/s, except 20% of the total area, where Vmis is

less than or equal to Vmin+0,5 mm/s

2) Comfort level is B if:

all Vmis values are less than or equal to Vmax

3) Comfort level is C if:

all Vmis values are less than or equal to Vmax+ 0,3

mm/s, except 20% of the total area, where Vmis is

less than or equal to Vmax +0,5 mm/s.

Fig 7 and Fig 8 are a graphic indication of the variousvibration limits for passenger ships, Fig 9 for heavy cargoships and Fig 10 for ships with length below 65 m.

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Figure 6 : Passenger ships - Vibration levels at full power - Table 1 of 2

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Figure 7 : Passenger ships - Vibration levels at full power - Table 2 of 2

Figure 8 : Heavy cargo ships - Vibration levels at full power - Table 1 of 1

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Figure 9 : Ships with length below 65 m - Vibration levels at full power - Table 1 of 1

2.4 Global comfort level

2.4.1 For the purposes of these rules, the global

vibration comfort level, defined in Sec 1, [1.1.4],is assigned as follows:

comfort level is A if all measured values are A level

comfort level is B if at least one measured value is Blevel and no values are C level

comfort level is C if all measured values are at least Clevel.

For passenger ships the comfort level is rated on basis of theactual rating reached by the passenger accommodationspaces, provided that at least C level, is reached in all otherlocations.

3 Testing procedures

3.1 instrumentation

3.1.1 Vibrometer

Vibration levels are to be recorded by means of a portableanalyser (vibrometer).

3.1.2 Calibration

Instrumentation is to be properly calibrated according to arecognised standard.

3.2 Measurements

3.2.1 Vibration level measurements are to be carried outby recording the spectral peak of structural velocity, inmm/s, in the frequency range from 1 to 100 Hz, by meansof a portable analyser connected to an accelerometer.

4 Forms

4.1 Characteristics of the ship4.1.1 Sec 1, Tab 6 indicates the suggested format forrecording data relative to the ship.

4.2 Characteristics of machinery

4.2.1 Sec 1, Tab 7 indicates the suggested format forrecording data relative to the ship machinery.

4.3 Measuring instrument

4.3.1 Sec 1, Tab 8 indicates the suggested format forrecording data relative to the measuring instrument.

4.4 Conditions during measurement

4.4.1 Sec 1, Tab 9 indicates the suggested format forrecording data relative to the conditions during measuring.

4.5 Measuring results

4.5.1

a) The following tables are an outline of the generalscheme in which the measurement positions of thevibration level are indicated.

b) In addition, for every measurement point, the spectrum

of the structural speed in the range of frequencies estab-lished, as determined by the portable analysers is to beenclosed, with the indication of the most importantpeaks.

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4.5.2 Sec 1, Tab 10, Sec 1, Tab 11, Sec 1, Tab 12 andSec 1, Tab 13 are the suggested formats for recording themeasurements carried out on suites, mini-suites, passengercabins and type A, B, C, D spaces of less than 120 m2.

4.5.3 Sec 1, Tab 14,Tab 12, Sec 1, Tab 16 and Sec 1,

Tab 17 are the suggested formats for recording the measure-

ments carried out on type A, B, C, D spaces of greater than

120 m2.

4.5.4 Sec 1, Tab 18 and Sec 1, Tab 19 are the suggested

formats for recording the measurements carried out on out-

side recreational spaces.

Table 3 : Characteristics of the ship

Table 4 : Characteristics of machinery

CHARACTERISTICS OF THE SHIP

Name of the ship

Register number - Ri

Flag

Port of registry

Name of the shipowner

Name of the shipyard

Place of building

Construction number

Type of ship

Dimensions Length - Lpp (m)

Breadth -B (m)

Depth - D (m)

Max. draught - T (m)

Displacement at draught T

Date of delivery

CHARACTERISTICS OF MACHINERY

Propulsion machinery Manufacturer

Type

Number of units

Max continuous power (kW)

Shaft speed (rev/min)

Main reduction gear Manufacturer

Type

Reduction ratioType of propeller Type of propellers

Number of propellers

Number of blades

Shaft speed at max. continuouspower (rev/min)

Main auxiliaries Manufacturer

Type

Number of units

Max continuous power (kW)

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Table 5 : Measuring instrument

Table 6 : Conditions during measurement

Table 7 : Measurement at 85% of full propulsion power - Detail

Instrument/Manufacturer

Analyser

AccelerometerCalibrator

Calibration of the acceler-ometer

Date in laboratory

Date prior to measuring

Calibration of the vibrome-ter

Date in laboratory

Date prior to measuring

Date

Starting time

Finishing time

Position of the ship

Type of voyage

Conditions during measurement Draught forward (m)

Draught aft (m)

Depth water under keel (m)

Weather conditions Wind force /speed (Bf -m/s)

Sea state / average wave height (SS -m)

Speed of the ship (knots)

Propeller shaft speed (rev/m)

Propeller pitch

Propulsion machinery speed (rev/m)

Propulsion machinery power (kW)

No. of operating propulsion machineries

No. of D/A operating enginesNo. of auxiliary machineries

Position No Type of space Area (m2) Vmis

1

2

3

......

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Table 8 : Measurement at 85% of full propulsion power - Summary

Table 9 : Measurement at full propulsive power - Detail

Table 10 : Measurement at full propulsive power - Summary

Table 11 : Measurement at 85% of full propulsion power - Detail

Table 12 : Measurement at 85% of full propulsion power - Summary

Total number of measurements

No. of measurements < Vmin %. of measurements < Vmin

No. of measurements < Vmin + 0,5 mm/s %. of measurements < Vmin + 0,5 mm/s

No. of measurements < Vmax %. of measurements < Vmax

No. of measurements < Vmax + 0,5 mm/s %. of measurements < Vmax + 0,5 mm/s

Resulting level A B C

Position No Type of space Area (m2) Vmis

1

2

3

......

Total number of measurements

No. of measurements < Vmin + 0,3 mm/s %. of measurements < Vmin +0,3 mm/s

No. of measurements < Vmin + 0,5 mm/s %. of measurements < Vmin + 0,5 mm/s

No. of measurements < Vmax + 0,3 mm/s %. of measurements < Vmax + 0,3 mm/s

No. of measurements < Lmax + 0,5 mm/s %. of measurements < Vmax + 0,5 mm/s

Resulting level A B C

Type of space Total area (m2)

Position No. Vmis Associated area (m2)

1

2

3......

Type of space Area (m2)

No. of points < Vmin %. of associated area

No. of points < Vmin + 0,5 mm/s %. of associated area

No. of points < Vmax %. of associated area

No. of points < Vmax + 0,5 mm/s %. of associated aea

Resulting level A B C

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Table 13 : Measurement at full propulsive power - Detail

Table 14 : Measurement at full propulsive power - Summary

Table 15 : Measurement at 85% of full propulsive power - Detail

Table 16 : Measurement at 85% of full propulsive power - Summary

Type of space Total area (m2)

Position No. Vmis Associated area (m2)

1

2

3

......

Type of space Area (m2)

No. of points < Vmin + 0,3 mm/s %. of associated area

No. of points < Vmin + 0,5 mm/s %. of associated area

No. of points < Vmax + 0,3 mm/s %. of associated areaNo. of points < Vmax + 0,5 mm/s %. of associated area

Resulting level A B C

Type of space Total area (m2)

Position No. Vmis Associated area (m2)

1

2

3

......

Type of space Area (m2)

No. of points < Vmin %. of associated area

No. of points < Vmin + 0,5 mm/s %. of associated area

No. of points < Vmax %. of associated area

No. of points < Vmax + 0,5 mm/s %. of associated aeaResulting level A B C