performance of this type of system is impressive, even better sound and vibration suppression can be achieved, particularly at the lower frequencies commonly produced by engines, propellers, mud pumps and so on, by combining the floating floor with the company's standard viscoelastic polymer plus SBR latex concrete system (Figure 1). The measured insertion loss, ILv, expressed in dB for this system over a range of frequencies is shown in Figure 2. Emtunga modules Swedac has developed similar but thinner (2 mm total) and lighter PVP laminate plates for attaching to bulkheads to reduce noise transmission between cabins. Emtunga has used these extensively in the construction of accommodation modules. In another variation on this theme, Swedac has supplied single steel sheets to Kvaerner with a layer of viscoelastic polymer that can be easily bonded to an existing steel surface. Kvaerner regularly uses this product on the plinths supporting water injection pumps on offshore platforms. Recognizing that noise and vibration problems may only manifest themselves when structures have been completed and that older vessels may need to be upgraded, Swedac has also developed a cassette damping system for retro-fitting to bulkheads, vessel sides and beneath floors -- essentially anywhere in the noise path -- within ships and offshore platforms. These are simply a narrow steel trough containing viscoelastic polymer into which has been set a series of steel lugs to allow welding to the structure. Swedac supplied its products and services widely in the offshore sector during the 1990s but suffered, like most suppliers, from the downturn towards the end of the decade. It switched its attention to the cruise ship market where it has ...
