BKL was retained by West Coast Manly Shipyard to provide consulting services on the acoustical design of four 33 m Torpedo and Ship Ranging Vessels (TSRV) for the Canadian Department of National Defence. The primary purpose of these vessels was to serve as floating acoustic labs for the joint Canadian/US naval facility at Nanoose Bay where acoustic signatures are measured on both torpedoes and ships. The primary acoustical requirement of the TSRV’s was to control underwater radiation of noise from diesel generators and other equipment to below ambient levels while the vessels are moored and operating in their “measurement mode”. A second requirement was to achieve shipboard noise levels of 60 dBA or lower in accommodation areas with the vessels under way at full power.
In order to control underwater noise radiation from ship service diesel generators, each of the two generator sets per vessel was mounted on a raft with two stage vibration isolation and totally enclosed in an acoustic enclosure. All connections were carefully designed to provide adequate flexibility and engine exhaust systems were isolated from the ship structure. To control shipboard noise levels with the vessels under way, main engines were isolated on single stage resilient mounts with flexible shaft couplings. All heating, ventilation and air conditioning systems were also carefully reviewed and silenced as necessary to achieve low noise levels both within accommodation areas and on exterior decks.
Throughout the two year construction period, BKL Consultants personnel made periodic visits to the shipyard to observe and comment on the progress of all noise control measures. Shop tests were carried out on all diesel generator sets prior to installation on the vessels to assure that the noise and vibration levels specified for this equipment were being achieved. Upon completion of each vessel, vibration spectra were measured, not only on the generator sets, but also on all auxiliary equipment that would be operating with the vessels operating in their “measurement mode”. Finally, shipboard noise surveys were carried out with the vessels underway at full power and underwater noise levels were measured at the Nanoose Bay Range. A “singing” propeller was encountered on one of the four vessels during sea trials but once this had been rectified, all of the specified noise and vibration requirements were satisfied on all four vessels.