Kongsberg Simrad SN90, Installation Manual

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381298/C
Noise sources
The operational performance of the SN90 Purse Seine and Trawl Sonar depends on the
noise conditions. It is essential that the noise signature is as low as possible.
The vessel’s hull, rudder(s) and propeller(s) must be thoroughly inspected in dry dock
prior to installation.
Roughness below the water-line deformities in the shell plating and protruding obstacles
can create underwater noise. These sources of turbulence must be smoothed or removed
as best as possible.
Note
It is especially important that the propeller(s) are not pitted or damaged.
Dry docking requirements
Whenever one or more transducers are mounted under the vessel’s hull, special
considerations must be made prior to dry docking.
Make sure that ample clearance is provided under the transducer when you are placing
the vessel in dry dock.
Do not place supporting blocks or structures in the vicinity of the transducer.
The location of the transducer must be noted on the vessel’s docking plan for future
reference.
Prior to dry docking, power down the SN90. Disengage the circuit breaker if necessary.
Label the Processor Unit and/or the circuit breaker clearly to prevent anyone from
powering up the SN90 accidentally.
Requirement for classification approval
Classification approval is required for the SN90 installation.
The SN90 transducer installation must be approved by DNV GL or another national
classification society.
The shipowner and shipyard performing the installation are responsible for obtaining the
classification approval.
Simrad SN90