As crew members work at sea for extended periods, the noise level in accommodation spaces directly affects rest quality and work efficiency. The International Maritime Organisation has made mandatory regulations on noise limits in various areas of a ship through the Code on Noise Levels On Board Ships. Jiangsu Haizhongzhou Shipping Industry Co., Ltd. takes noise control as one of the core indicators of interior outfitting, forming a systematic noise reduction scheme from sound insulation material selection, structural design to installation techniques.
The first step in noise control is to identify the main noise sources and transmission paths. Noise sources on a ship mainly include the main engine, auxiliary engines, propeller, pumps and ventilation systems. Noise reaches accommodation spaces through two paths: airborne sound and structure‑borne sound (vibration transmission). Haizhongzhou performs noise prediction at the design stage, using statistical energy analysis software or finite element software to calculate the expected sound pressure level in each compartment, and takes noise reduction measures for areas exceeding the limit.
The selection of sound insulation materials is fundamental. Haizhongzhou selects different materials according to the compartment location and fire rating. For partitions between accommodation cabins, high‑density rock wool boards are used, with a thickness of fifty millimetres, a surface density of not less than 80 kg/m², and a weighted sound reduction index reaching over 45 decibels. For decks between the engine room and accommodation areas, a composite sound insulation structure is used: a vibration‑damping pad is first laid on the steel deck, followed by a fifty‑millimetre thick mineral wool board, then a forty‑millimetre thick lightweight cement screed, and finally PVC tiles or ceramic tiles. This floating floor structure effectively blocks structure‑borne sound transmission.
The installation technique of sound insulation materials is equally critical. Haizhongzhou requires that insulation boards be laid with staggered joints, and the gaps between boards be filled with sealant, leaving no voids. The connection between insulation boards and steel bulkheads/decks uses damping adhesive rather than rigid fixation, avoiding the formation of sound bridges. When penetrations (such as pipes, cable conduits) pass through the insulation layer, fire‑resistant sound insulation sealant must be filled at the penetration and wrapped with sound insulation tape. Doors and windows are weak points in sound insulation. Haizhongzhou selects sound‑insulated doors with a sound reduction index of not less than 30 decibels, with two sealing rubber strips between the door frame and door leaf; for windows, double‑glazed units are used, with 6 mm glass and a 12 mm air gap.
Vibration control inside compartments is also important. Haizhongzhou installs rubber vibration isolators under the bases of vibrating equipment such as air conditioners, fans and pumps, and uses flexible hoses for the inlet and outlet connections of the equipment. Rubber pads are added to the hangers of ventilation ducts to prevent duct vibration from being transmitted to the bulkheads through the hangers. During commissioning, Haizhongzhou uses a sound level meter to measure the actual noise level in each compartment during sea trials. The measurement position is at least one metre from bulkheads and 1.2 metres above the floor. For accommodation cabins, the background noise is required not to exceed 55 dB(A); for the engine control room, not to exceed 75 dB(A). The measured data are compared with the design values, and areas with deviations exceeding 3 dB are analysed and corrected.
