When used as a trawling sonar, the Simrad SN90 sonar can be provided with the SN92H Hull Unit.
The hull unit allows you to retract the transducer when the SN90 is not in use, and thus protect it against ice and objects in the sea. The hull unit is supplied with 7 m transducer cable. The transducer is mounted with a fixed 30 degrees tilt.
A. Hand crank for manual hoisting and lowering
When the sonar is turned on, press the Down button on the Operating Panel to lower the transducer into the water. Before the sonar is switched off, press the Up button on the Operating Panel to retract the transducer into the installation trunk for protection. If you forget this, the transducer is hoisted automatically before the sonar is turned off. It is also hoisted automatically if a serious malfunction occurs to the communication between the bridge and the hull unit.
The transducer can also be lowered to any selected middle position. In case of power failure, the transducer can be raised or lowered manually by means of a hand crank.