Low noise and vibration behavior in ships are important to ensure that passengers have a pleasant journey. The marine floor constructor, Sika Marine, collaborates with FORCE Technology's acoustics team to tackle the issue of quantifying the reduction of structure borne noise.

Noise- and vibration level vital for passenger satisfaction

Today, one of the most important issues for vessels is low noise and vibration behavior. This applies especially for cruise ships and luxury yachts. A cruise ship with poor reputation regarding noise will often result in complaints from passengers, leading to loss of sales.

When building a new ship, the use of noise and vibration prediction tools in the design and building phases can minimise the risk of noise and vibration problems. Furthermore, a noise prediction can ensure that the vessel will comply with specific noise criteria and give the shipyard or shipowner an idea of the extent of necessary noise reducing measures already at the design stage.

Noise reduction measures

Sika Marine AG, the marine division of Sika and a world leader in marine acoustics technology and solutions, is collaborating with the acoustics team at FORCE Technology (former: DELTA) to tackle the issue of quantifying the reduction of structure borne noise by measuring the damping properties of their floor solutions for commercial vessels.

Tony Jenkins, Key Account Manager in SikaFloor® Marine says:

“The practice for producing measurable values for airborne and impact noise reduction on ships is well established and the performance of these various systems can be quantified. However, there is currently no ISO standard for measuring structure borne sound and damping properties for marine floors and bulkheads. Working with FORCE Technology's acoustics team, we are now able to document this reduction of magnitude and provide this information to the acoustics experts involved in the design of vessels.”

Predicting noise and vibration

As an outcome of DELTA’s merger with FORCE Technology, we can now offer a wider range of services to our maritime customers – also within noise and vibration on ships. We can predict excitation forces from the propulsion system using propulsion hydrodynamic and computational fluid dynamic capabilities. The structure borne noise source strengths from the other main noise sources, e.g. auxiliary engines’ main compressors, and ventilation units are used as excitation forces in the noise prediction model.

With this knowledge, together with the vessel layout and the accommodation build-up, a noise prediction can be performed and the results compared to the noise. Based on the results acoustic noise reducing construction e.g. floating or vibration damped floor constructions, can be introduced to fulfil the noise criteria.

In order to do this, knowledge about the noise reducing properties of these constructions is necessary for prediction of the expected noise levels with these constructions applied.

Structure borne noise insulation

The noise reducing properties of marine floors can be measured in our acoustical laboratories at the Technical University of Denmark (DTU), in which we can install a test section of a ship deck (10 m2) and perform different acoustical tests. The sound tests are the measurement of sound insulation properties and impact sound insulation properties according to ISO 10140.

However, in most areas of vessels the structure borne noise insulation properties are the most important parameter for the noise. These properties are measured using a dynamic exciter as an excitation force on the mounted test deck. Measuring the parameters with and without the noise reducing floor, the effect of floor systems can be determined.

Furthermore, FORCE Technology undertakes independent noise and vibration investigations e.g. checking for conformance of noise and vibration requirements, trouble-shooting assignments for investigation of noise or vibration problems. These investigations are designed to find the course of the problem and to recommend potential solutions using vibration or noise control measures.

Read also the case about sound emissions measurements from machinery at Haarup Maskinfabrik.