Page 84: of Maritime Reporter Magazine (September 1999)

Marine Propulsion Annual (Continued from page 17) there is a plethora of international and national codes that both recommend and demand maximum permissible noise levels aboard ships.

Additionally, scientific evidence regarding the effects of noise on every- thing from shipboard personnel to whales is sure to raise the bar in regards to noise control in years to come. Sim- ple in statement, yet complex in real- world delivery, continuing efforts to reduce emissions, noise and vibration signatures aboard vessels of all types and sizes is a technological challenge, particularly given the acoustical proper- ties of water and of the primary materi- als utilized in shipbuilding.

MAN B&W has continued to lead the charge on many diesel engine R&D fronts, and has published a report enti- tled "Diesel Engines and the Environ- ment - Noise." The company's efforts in the field of environmental issues ar numerous, and it has earned it the Dan ish Environmental Prize for developin: plant for removing nitric oxides fron exhaust gases.

The company notes that whereas noisi was traditionally considered a "neces sary evil," today excessive noise is con sidered a form of pollution with fai reaching ramifications. In general, the brochure notes that noise emitted by the engine's exhaust gas, and the structure borne noise excited by the engine, are so low that it is possible to keep within the noise requirements for the bridge wing and accommodation. On the other hand, airborne noise emitted from the engine in the engine room is so high that in some cases there is a risk that the noise limits for the engine room cannot be met, unless additional noise mea- sures are introduced. Hence, the com- pany sees future efforts pointed toward developing an engine with reduced air- borne sound levels.

The Sound Of Silence

Soundcoat's noise and vibration reduction products have gained wide acceptance in broad applications in the marine industry from nuclear pow- ered submarines to high performance pleasure craft and production vessels.

Soundcoat's Acoustical Product line consists of three main categories of products: Acoustic Absorbers designed to absorb reverberant noise,

Sound Barriers to block the path of

Airborne noise and Damping Materi- als to dissipate Structure-borne noise.

Absorptive materials known as

Soundfoam are generally porous light- weight foamed plastic composites designed to lower higher frequency noise problems and reverberation in contained environments such as engine and passenger cabins. Most of these products offer combustion-mod- ified fillers or resins to meet high fire and smoke resistant ratings.

Barrier products, known as Sound- mat PB, are designed to contain or block the airborne noise path and are designed to line thin gauge sheet metal, wood and composite walls on vessels that may be found with bulk- heads, soles, decks and cabin walls of smaller craft.

Damping products, such as Dyad,

Soundfoil and GP-Damping Sheet are to reduce structure borne-noise and panel resonance. For thicker steel and metal surfaces such as hulls, bulk- heads and decks as found on larger vessels, Dyad is designed to stop the noise from traveling extensively and readily through the ship structure.

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