The challenges
Taiwanese Coast Guard commissioned its two largest patrol vessels, the 119 metre, 3,000 ton sister vessels CG-128 Yilan and CG-129 Kaohsiung. With a maximum crew of 50 and advanced weapons systems, the vessels will beef up the CGA’s patrols and operations in the open sea.
Pyrotek was asked to consult on the build, as the noise levels in strategic cabins within the vessels were substantially higher than the recommended levels.
Cabins in the ships that were of particular concern were the security room, hospital and two accommodation cabins, 16 and 17. Testing revealed the noise levels in these rooms were unacceptable.
There were Immediate safety concerns associated with noise on a vessel such as this. Specifically, noise can:
1. Mask signals
2. Intrude on speech communications
3. Interfere with the thought process and concentration
4. Disrupt sleep
5. Cause fatigue
‘The new noise level limits are designed to ensure that within each day or 24-hour period, the equivalent continuous noise exposure to which seafarers will be subject to will not exceed 80 dB(A). In spaces where noise levels exceed 85 dB(A) appropriate hearing protection should be worn and no crew member should be exposed unprotected to peak values exceeding 135 dB(A).’
The Taiwanese Coast Guard had requested the noise levels experienced should be under 70 dB(A) at 85% engine power output. This level of noise would bring the vessel into line with the new IMO standards and provide a safer operational environment for all workers.
The solutions
Pyrotek sales engineer Dollars Wang consulted with our experienced marine advisors Bradley Scott and Tom Metzner from the Australian head office to specify a solution.
Drawing on Pyrotek’s extensive knowledge and experience in marine soundproofing the following specialised marine noise control products were specified as a solution:
1. Installation of Wavebar into the existing floors below the vinyl floor 2. Installation of Wavebar into the perimeter walls of cabins inside a decorative finish 3. Strategically-placed installation of Decidamp DC30 to control structure-borne noise and vibration.
Wavebar was the ideal solution to improve the acoustic performance of existing walls and floors in the vessels’ affected cabins.
During vessel construction, limited use of vibration damping allowed for noise to flank existing insulation on bulkheads, decks – using the structure itself as the path and re-radiate into air-borne noise, affecting nearby cabins.
The installation of DC30 significantly reduced the amount of vibration noise radiating from the fuel tank rooms.
The results
Post-installation at sea-testing revealed noise levels had been significantly reduced in all treated areas, resulting in a much safer environment for workers who operate in the affected areas.
The treatments specified and installed into the vessels ensure that the rooms are closer to compliance with the new IMO standards, which will govern all new vessels built after July 2014. The treatment was also able to reduce noise levels substantially below the requested 70 dB(A) at 85% engine power output.
Feedback received from both the construction firm Jade Yachts and the Taiwanese Coast Guard has been extremely positive and the performance of Pyrotek’s products has exceeded the expectation of both parties who are impressed with overall performance.
Feedback has been extremely positive and the performance of Pyrotek’s products has exceeded the expectation of both parties who are impressed with overall performance.
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