Ship acoustics

Acoustic optimisation on ships is not a luxury but a necessity: passengers should feel comfortable on board, the crew should be able to carry out their responsible work without external disturbances. Relaxation should be possible in living and rest areas. For safety reasons, the perception of warning signals and their intelligibility must be guaranteed everywhere on board at all times. Also, the sound generated and emitted by the ship should not pollute the marine environment.

However, acoustic conditions on ships are extremely complex: on board, usually there are strong noise and vibration generators such as diesel engines, cooling compressors, pumps or propulsion systems. The typical ship structures as well as piping and duct systems provide ideal propagation conditions for sound and vibrations on board and into the water. At the same time, the portfolio of technical countermeasures is usually limited for reasons of space and weight.

Müller-BBM's range of ship acoustics services is as diverse as shipping itself. Our field of work includes yachts, passenger, merchant and research vessels as well as naval ships. We provide consulting services to shipyards, shipping companies, design offices, suppliers of technical ship equipment as well as authorities and the German Navy in all phases of a ship's life, from planning, construction and acceptance to operation.

We support you in ship acoustics with:

We are accredited for acceptance tests according to the IMO Resolution MSC 337(91) and the Construction Regulation 0450 for watercraft of the German Armed Forces as well as for acceptance tests according to ISO 20283-5, Mechanical vibration - Measurement of vibration on ships - Part 5: Guidelines for measurement, evaluation and reporting of vibration with regard to habitability on passenger and merchant ships.

Acoustic planning, accompanying consulting services and acoustics management

Optimal solutions result when acoustics and vibration control are "thought through" already in the early concept phase, coordinated with other trades and continuously taken into account, monitored and controlled as the project progresses. In this way, the sound insulation concept and the acoustic target values/specifications can be continuously checked and adapted. Therefore, ideally, we support you in the acoustic planning already when preparing the acoustic specification of the overall system, e.g. by specifying target values.

As the project progresses, the acoustic assessment of the planning status is regularly updated. Data from materials, components and noise generators are considered according to the state of documentation or taking into account measurement results and numerical calculations.

As part of the accompanying consulting services, we also support you, if required, with the preparation of guidelines and recommendations for low-noise constructions as well as with the development, specification, design and evaluation of individual acoustic measures, concepts and constructive details.

Experimental investigations

Qualified metrological investigations are required with different objectives. The recording of airborne and structure-borne sound data or of fluid sound at the equipment supplier or at the ship's shell serves the purpose of continuous quality control. In addition, the measurement data can be used as input data for acoustic forecasts, if necessary.

Within the scope of quality management, Müller-BBM carries out acoustic acceptance tests according to accredited procedures (standards) on individual units or on the entire system (for details see, among others, ISO 3744, ISO 20283-3, Construction Regulation 0450 for Watercraft of the German Federal Armed Forces, as of 2016). An evaluation is carried out according to the specifications of the end customer (acoustic specification) or suitable standards. In naval ship building, for example, the US standards MIL-STD-1474E (airborne sound, formerly MIL-STD-740-1(SH)) and MIL-STD-167-1A (vibration and structure-borne sound, formerly MIL-STD-740-2(SH)) are commonly used.

Acoustic acceptance tests

Acceptance tests are typically carried out in the following project phases:

FAT -  Factory Acceptance Test / factory inspection:

Acceptance tests for airborne and structure-borne sound radiation of individual units, evaluation according to a customer specification or a standard.

HT/HAT - Harbour Acceptance Test / pier test:

On board in installed condition, airborne sound measurements for air-condition and ventilation systems, building and room acoustical in-situ measurements, quality control (e.g. acoustic decoupling of machinery), structural-dynamic investigations on ship foundations and on the ship’s structure as well as the determination of transmission properties (e.g. impedance, flanking paths such as piping) are carried out. In addition, preliminary testing for SAT is carried out by measuring underwater sound next to the hull as well as airborne and structure-borne sound in the boat/on the ship.

SAT - Sea Acceptance Test / sea test:

Measurements of airborne noise (also acceptance tests according to the IMO Resolution MSC 337(91)), naval building regulations).

Vibration measurements (also acceptance tests according to ISO 20283-5, Mechanical vibration - Measurement of vibration on ships - Part 5: Guidelines for measurement, evaluation and reporting of vibration with regard to habitability on passenger and merchant ships).

Structure-borne sound: recording simultaneously with the acceptance test for further diagnosis.

Waterborne sound: mobile underwater sound measuring equipment, measurements of radiated underwater sound and transient noise.

Müller-BBM is accredited for all relevant procedures of FAT/HAT/SAT.

Special investigations

For the detailed investigation of noise and vibration phenomena on ships and on ship equipment, we have a wide range of powerful experimental methods in acoustics and vibration engineering. We use them to characterise acoustic systems and to determine sound transmission properties. With these, we can develop adapted acoustic measures.

For example, we apply Operational Transfer Path Analysis (OTPA), Modal Analysis (MA), operational vibration analysis or impedance measurements together with efficient measurement technology. For this purpose, we use the PAK® measurement and analysis software of our sister company Müller-BBM VibroAkustik Systeme. PAK® allows multi-channel simultaneous acquisition of acoustic and vibration-related data. If required, the most important ship parameters such as GPS position, speed, propeller speed or drive torque can also be recorded.

 

 

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