Verifying the quality of the hull unit installation
A quality inspection must take place after the hull unit has been installed, and while the vessel is still in dry dock. The inspection shall verify that the sonar room meets the requirements, and that the hull unit has been installed correctly.
Prerequisites
The vessel is in dry dock.
Procedure
1 Make sure that the sonar room requirements are met.
2 Make sure that the unit is not physically damaged, and that the surfaces and paint-work are clean without dents or scratches.
The physical handling during the installation may have caused some minor scratches to the surfaces or paint-work. This can be accepted. However, if rough handling has caused serious damage, this must be recorded with a written statement and necessary photos, so that corrective actions can be made.
3 Make sure that the physical installation of the unit has been completed.
a Make sure that the welds and brackets used to support the hull unit are substantial enough to hold the unit securely under all operating conditions.
b Make sure that the compartment ("sonar room") in which the hull unit is mounted is clean and dry.
c Make sure that ample space is provided around the unit to allow for maintenance and replacement of parts.
d Make sure that all welds and brackets have been painted with the correct preservation medium to prevent corrosion.
4 Make sure that cable installation has been completed.
a Make sure that all cables leading to and from the unit have been properly mounted and secured.
b Make sure that the unit is securely connected to the ship's ground with an earthing strap.
c Make sure that enough slack has been provided on each cable to allow for maintenance and replacement.
d Make sure that the transducer cables can move freely when the transducer is lowered and hoisted.
5 Make sure that there are no corrosive attacks on the hull unit, mounting flange, installation trunk, support brackets or other parts of the installation.
6 Make sure that all relevant actions have been taken to reduce flow noise.
a The hull plating in front of the transducer must be as smooth as possible.
Important
Be especially aware of bilge keels and sacrificial anodes. The keel must be rounded off without sharp edges. Neither extruding objects nor abrupt transitions must be present. Fill the space around any mounting bolts, as well as dents and cracks in the plating, with a a suitable filling compound (putty).
b The fairing around the installation trunk must be streamlined.
7 Fill in the result table.
Result
Requirements Results
The compartment in which the hull unit is installed ("sonar room") is clean and dry.
The sonar room meets all requirements related to the vessel’s watertight integrity.
The sonar room meets all size and access requirements. The access hatches are suitably constructed and located.
The sonar room meets all requirements related to insulation, heating and ventilation.
The sonar room meets all requirements related to electrical installations, including light, power, communication and cabling.
A bilge pump is installed.
The sonar room is suitably decked.
The hull unit is correctly installed with easy access for maintenance and replacement of parts.
All cables are properly mounted with enough slack.
The transducer cable can move freely when the transducer is lowered and hoisted.
All relevant parts have been painted with the correct preservation medium to prevent corrosion.
There are no corrosive attacks.
All relevant actions have been taken to reduce flow noise.
Further requirements
If the inspection reveals errors, inaccuracies or unfortunate dispositions related to units, devices or cables, use the Installation remarks form to document these. If necessary, write a full report, and attach high resolution photos.