Onboard Noise Survey Operating Conditions and Report Checklist

Start with the decision the noise survey must support

“Measure the vessel noise” is not a complete scope. The same sound-pressure reading may be used for statutory review, owner acceptance, sea-trial documentation, a cabin complaint, repair verification or source diagnosis. Each decision needs a different location plan, operating matrix and evaluation basis.

Build an operating-condition matrix before choosing measurement points

Noise changes with propulsion, generator loading, ventilation, cargo equipment, thrusters, doors, windows, weather and vessel activity. A location list without an operating matrix can produce precise readings that answer the wrong question.

A harbour measurement, anchorage investigation and sea-trial acceptance survey are not automatically interchangeable. Record the actual condition and avoid relabelling one as another after the event.

Design the measurement-location schedule

Use general arrangement drawings, accommodation plans, machinery layouts and the governing requirement to create a numbered location schedule. Every result should map to one identifiable space and measurement position.

• Group accommodation, navigation, control, workshop, machinery and open-deck positions.
• Identify occupied spaces and complaint locations that require repeat positions.
• Record microphone height and position conventions required by the agreed method.
• Separate area-noise measurements from personal noise-exposure monitoring.
• Add diagnostic positions only where they support a source or transmission hypothesis.
• Mark inaccessible, unsafe or unavailable spaces before attendance, not after reporting.

For work-shift exposure, use the separate personal noise-exposure monitoring service. For transmission through cabins, doors or bulkheads, use sound-insulation testing.

Control the instrument and calibration evidence

The instrument chain must match the agreed code, contract or diagnostic purpose. IEC 61672-1 provides specifications for sound level meters, but the required performance category and supporting verification depend on the project basis.

Calibration evidence supports traceability; it does not by itself prove that the vessel condition, location selection or evaluation method was correct.

Measure enough to answer the question—without mixing methods

Area noise surveys commonly use equivalent continuous A-weighted levels over a defined period, with maximum, peak or frequency-band information added where the governing basis or diagnostic question requires it. The quantity, weighting, duration and averaging method must be declared.

• Allow the intended operating condition to stabilise before sampling.
• Keep the operator and reflective objects from unnecessarily influencing the microphone field.
• Repeat or extend measurements when the level is unstable or contaminated.
• Use octave or one-third-octave spectra when tonal, low-frequency or source-path evidence is needed.
• Record abnormal events and do not average them into a compliance result without justification.
• Keep diagnostic observations separate from formal acceptance results.

The IMO Code on Noise Levels on Board Ships was adopted by resolution MSC.337(91) and includes a noise survey report format. Applicability still depends on the vessel and statutory basis, so the current requirement should be confirmed before the survey.

What a review-ready onboard noise report should contain

1. Vessel identification, survey purpose, date, location and attendance parties.
2. Applicable code, contract, class/flag submission context and agreed criteria.
3. Instrumentation, serial numbers, calibration traceability and field checks.
4. Measurement locations with drawings or an unambiguous schedule.
5. Propulsion, machinery, HVAC, environmental and activity conditions.
6. Measured quantities, durations, weightings and frequency-band results where used.
7. Evaluation table showing pass, exceedance, observation or not-evaluated status.
8. Deviations, inaccessible spaces, contaminated measurements and other limitations.
9. Diagnostic interpretation clearly separated from measured fact.
10. Corrective priorities and a precise verification/retest scope where requested.

Class, flag and supplier-qualification context

Supplier qualification and project report acceptance are separate decisions. The required route may depend on the flag administration, classification society, class notation, statutory basis, contract and attending surveyor. Confirm these requirements before mobilisation for an ABS-, BV-, CCS-, CRS-, DNV-, IRS-, KR-, LR-, ClassNK-, PRS-, RINA- or Türk Loydu-classed vessel.

This guide supports scope preparation for classed and flagged vessels. It does not state that Vessel Doctor is an approved or recognised service supplier and does not guarantee report acceptance.

Five items to send for a fast feasibility review

1. Vessel name, type and IMO number.
2. Port/berth/anchorage or trial area, ETA/ETD and access window.
3. Survey purpose and the requirement, specification or complaint to be addressed.
4. Spaces, RPM/load points and machinery/HVAC combinations.
5. Required report, witness, review route and deadline.

Attendance can be assessed for Singapore, Malaysia, India, Sri Lanka, Indonesia, Thailand, the Philippines, the Middle East, Asia-Pacific and worldwide, subject to access and availability.