Hull unit description
The hull unit provided with the CS90 is designed to lower the transducer down below the ship’s hull when the CS90 shall be used. When the CS90 is switched off, the transducer is hoisted for protection.
The hull unit is designed to lower the transducer 1.0 or 2.1 meters below the ship’s hull. Maximum vessel speed with the transducer fully lowered to 1 meter is 20 knots. Maximum vessel speed with the transducer fully lowered to 2.1 meter is 19 knots.
The CS90 Fish Finding Sonar can be provided with one of the following hull units.
Hull Unit Part
number
Lowering
depth
Transducer
cables
Maximum
speed
CS90 439051 1.0 m 4.6 m 20 knots
439054 10 m 20 knots
CS94 439057 2.1 m 4.6 m 19 knots
439058 m 19 knots
Outline dimensions drawings:
- CS90: 439719
- CS94: 439723
The same transducer is used on all hull unit types. Due to the different flange diameters, different installation trunks are used.
Installation trunk Upper
diameter
Bottom
diameter
Part
number
Drawing Blind flange
CS90 370 mm 273 mm 408615 402509 051344
CS94 760 mm 610 mm 427423 427176 207485
760 mm 356 mm 434529 434524
The hull unit is a large mechanical construction. It is mounted on the top of the installation trunk. 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. This location is recommended to avoid the noise from the propellers and the engine.
The purpose of the Motor Control Unit is to control the hoisting motor on the hull unit. When you make the appropriate commands on the CS90 sonar, the Motor Control Unit will start and stop the motor. It will also make sure that the motor rotates the correct way. The motion sensor for the built-in electronic stabilization of the sonar beams is provided.
•  To lower the transducer, press Down on the Operating Panel. To indicate transducer movement, the Down indicator lamp flashes, and an audible signal is sounded. When the bottom position has been reached, the indicator lamp is lit, and the audible signal stops.
•  To retract the transducer, press Up on the Operating Panel.
The transducer can also be lowered to any selected middle position. On the Operating Panel, press Middle. In case of power failure, the transducer can be raised or lowered manually by means of a hand crank.
Note
If you forget to hoist the transducer before the CS90 is switched off, the transducer is hoisted automatically before the power is disconnected. The transducer is also hoisted automatically if a serious malfunction occurs to the communication between the bridge and the hull unit.
Caution
If the transducer hits larger objects or bottom, the transducer shaft may be bent, or - in worst case - it can be broken off. A broken transducer shaft will cause water leakage through the top of the shaft. If you suspect that the transducer shaft is seriously damaged with holes, do not retract the transducer to its upper position.
To prevent serious damage to the vessel or the vessel stability, you must have a water pump and a warning system in the sonar room.
On some vessels, additional transducer protection is required. One example is vessels working in arctic conditions. It is important for them to prevent ice from damaging the transducer. A gate valve can then be added to the hull unit installation. By means of a mechanical construction it shuts off the bottom of the installation trunk when the CS90 is not used.
Two different gate valves types are used.
•  DN350
•  DN500
The gate valves are manufactured by LK Valves. For more information, refer to the end-user documentation provided by the manufacturer.