About the hull unit installation
The hull unit is used to lower the transducer down below the ship’s hull when the SU90 system shall be used. When the SU90 system is turned off, the transducer is hoisted for protection. The hull unit is large and crucial part of the sonar system.
The SU90 system can be provided with one of the following hull units:
Hull Unit Lowering depth (m) Transducer cable (m) Maximum speed (knots)
SU92 1.2 4.6 21
7
SU93 1.6 4.6 16
7
SU94 2.1 4.6 11
7
The same transducer is used on all hull unit types.
If a Hull Unit Controller is supplied with the system, the Motor Control Unit cabinet is used as a junction box.
Note
Due to its physical size and weight, and the fact that the installation trunk penetrates the vessel hull, it is very important that the hull unit is installed and secured properly. The hull unit gantry must be secured to the bulkhead by means of mechanical support brackets. The dimensions and strength of the support brackets must be adequate to prevent vortex induced vibrations. This is an invariable requirement to ensure the safety of the SU90 system and the vessel.
The hull unit shall be mounted on top of the installation trunk at the bottom of the hull. The installation trunk penetrates the ship’s hull, and allows the transducer to be lowered into the sea. The hull unit is normally located in the forward part of the vessel.
As a general recommendation, the hull unit shall be oriented with the hoisting motor pointing aft. If this orientation makes it difficult to access electrical connections, the hull unit may be rotated during its installation to the most suitable direction.
Appropriate lifting equipment (lifting tackle, portable crane or ship’s crane) is required. Free access through the hull or the decks over the installation trunk must be provided.