Section 4 Testing

4.1.1 These requirements take precedence where quoted standards may differ.

4.1.2 The trial measurements may be undertaken by an approved technical organisation as defined in Pt 7, Ch 12, 4.7 Approved technical organisation or by LR. In the former case, the measurements are to be witnessed by a LR Surveyor.

4.1.3 Subject to agreement by LR and the Owner/ Operator, the measurements may be undertaken by the Builder. In this case, the measurements are to be witnessed by a LR Surveyor.

4.2.1 Test conditions for the surveys are to be in accordance with those detailed in ISO 2923 and ISO 20283-5 as applicable.

4.2.2 The intended operating and loading conditions of the ship during assessment surveys are to be submitted to LR for agreement, prior to commencement of surveys.

4.2.3 Surveys are to be conducted when the ship is fully outfitted and all systems contributing to noise and vibration levels are operational.

4.2.4 The test conditions required for the vibration and noise measurements are to be in accordance with the following conditions:

1. For passenger ships, prior to measurement surveys being carried out, the ship operating condition where the worst conditions are experienced between 0 and 85 per cent maximum continuous rating of the propulsion machinery is to be determined. To establish this condition, four measurement positions are to be defined with the agreement of LR and measurements taken of the parameters of interest at ship speeds corresponding to percentages of the maximum continuous rating of the propulsion machinery increasing up to 40 per cent MCR in 10 per cent intervals and from 40 per cent in 5 per cent intervals up to the 85 per cent maximum continuous rating of the propulsion machinery. If the 85 per cent maximum continuous rating condition is found to be the worst condition, then this will form the trial operating conditions. However, if a lower speed condition is found to be worse than the 85 per cent maximum continuous rating condition then both that condition and the 85 per cent maximum continuous rating condition will form the trial operating conditions. Where unavoidable any barred range within the values required for the trial operating condition may be excluded on agreement between Owner and Builder subject to approval by LR. Other operating conditions for testing can be agreed between Owner and Builder.

2. The power absorbed by the propeller(s) is to be that defined in Pt 7, Ch 12, 4.2 Test conditions 4.2.4. Alternatively, by special agreement, some lesser power could be accepted if it can be demonstrated by the Owner that this would correspond to a more representative normal service condition.

3. Auxiliary machinery essential for the ship's operating conditions together with HVAC systems are to be running at their normal rated capacity during the noise and vibration trials. Combinations of auxiliary machinery operation may be necessary. In addition, the following equipment is to be running if appropriate: stabilisers, waste treatment equipment, swimming pool and jacuzzi equipment.

4. For sea-going ships, measurements are to be taken with the ship proceeding ahead, at a constant speed and course, in a depth of water not less than five times the draught of the ship. For other ships, an appropriate water depth is to be agreed with LR prior to the trials.

5. Trials are to be conducted in sea conditions not greater than sea state 3 on the WMO sea state code. In addition, noise measurements should not be taken when the wind force exceeds 4 on the Beaufort scale.

6. The ship is to be at a displacement and trim representative of an operating condition.

7. Rudder angle variations are to be limited to ±2° of the midship position and rudder movements are to be kept to a minimum throughout the measurement periods.

8. In addition, for ships which are designed to spend a considerable period of time in harbour, the noise and vibration, are to be measured for this condition, with the auxiliary machinery and HVAC systems running at their normal rated capacity.

9. Intermittently run equipment such as transverse propulsion units are to be operated at 40 per cent of their rated power for additional measurements in surrounding ship areas. If such equipment is intended for long-term operation, e.g. stabilisers, or long-term intermittent dynamic positioning (DP) mode, measurements shall be made for ensuring compliance with the general noise and vibration limits. If such systems are intended for short term intermittent operation only, for instance during port manoeuvres, the noise and vibration levels should be measured for information only. Definition of long-term DP mode can be agreed between Owner and Builder.

4.2.5 Prior to survey, a test programme is to be submitted for approval by LR. This programme is to contain details of the following:

1. Measurement locations indicated on a general arrangement of the ship.

2. The ship's loading condition during survey.

3. The machinery operating condition, including HVAC system, during survey.

4. Noise and vibration measuring equipment.

4.3.1 Noise measurements are to be conducted in accordance with ISO 2923 and IMO Resolution MSC.337(91) – Adoption of the Code on Noise Levels on Board Ships – (Adopted on 30 November 2012)The Annex below is consolidated into Resolution MSC.337(91). Measurements of noise levels are to be carried out using precision grade sound level meters conforming to IEC 61672-1, Type 1 or 2. Subject to demonstration, equivalent standards are acceptable.

4.3.2 Where the measured noise level exceeds the relevant criterion by 3 dB(A), or contains subjectively annoying low frequency noise or obvious tonal components, octave band readings are to be taken, with centre frequencies from 31,5 Hz to 8 kHz.

4.3.3 When outfitting is complete, and all soft furnishings are in place, sound insulation indices for passenger spaces are to be determined in accordance with ISO 16283-1. Cabin to cabin indices are to be determined from a minimum of three locations for each cabin type within the passenger accommodation, the number of test locations being agreed with LR. If the partition surface area is less than 10 m², an area of 10 m² shall be used for the calculation of the R′_w index, unless otherwise agreed.

4.3.4 If required, impact sound measurements are to be carried out in accordance with ISO 16283-2 and presented in accordance with ISO 717/2. See Pt 7, Ch 12, 4.4 Noise measurement locations 4.4.4.

where n is the total number of passenger cabins.

At least 40 per cent of the crew cabins shall be measured. For ships with a large number of crew cabins, e.g. cruise ships, a minimum of 15 per cent of the crew cabins should be measured. 50 per cent of the measurements in crew and passenger areas shall be located in the after third of the ship. Distribution of the measurement locations is to be agreed by LR.

4.4.2 During measurement trials, recognised noise sources are to be operated at their normal level of noise output (e.g. machinery at design rating).

4.4.3 In larger sized spaces, where noise levels may vary considerably, such as restaurants, lounges, atria and open deck recreation areas, measurements are to be taken at locations not greater than 7 m apart.

4.4.4 The number of and locations for impact noise measurements are to be agreed between the Builder, Owner and LR. The measurements are to be carried out when the ship is in a condition with steady and low background noise. The number and location of measurements are to take account of all different combinations of construction, areas of application, types of cabin and spaces below.

4.5.1 Vibration measurements are to be conducted in accordance with ISO 20283-5.

4.5.2 Measurements are to be made with instrumentation meeting the requirements of ISO 8041.

4.5.3 Vibration levels are to be given in terms of the velocity measurement appropriate to the version of the standard being used and should be measured over a period of not less than one minute.

4.6.1 Measurement locations are to be chosen so that the assessment represents the overall vibration environment onboard the ship. To minimise survey times, readings may be taken at the locations previously defined for the noise assessment part of the survey.

4.6.2 In cabins, vibration readings are to be taken in the centre of the floor area. The measurements are to indicate the vibration of the deck structure. In large spaces, such as restaurants, sufficient measurements are required to define the vibration profile.

4.6.3 Where deck coverings make transducer attachment impracticable, use of a small steel plate having a mass of at least 1 kg, with spikes as appropriate, is permissible.

4.6.4 At all locations, vibrations in the vertical direction are to be assessed. Sufficient measurements in the longitudinal and transverse directions are to be taken to define global deck vibrations in at least two locations on each deck.

4.7.1 An approved technical organisation for the purposes of these Rules is one that is acceptable to the Owner and LR with proven capability in noise and vibration measurement and satisfies all the criteria set out below:

1. Have instrumentation whose calibration, both before and after the measurements, can be traced back to National Standards and, hence, back to International Standards.

2. Have analysis procedures capable of data reduction to the requirements and standards set out in these Rules.

3. Be able to provide a written report in English with contents as defined by Pt 7, Ch 12, 5 Noise and vibration survey reporting.