Hull units

The Simrad MF90 fish-finding sonar can be provided with one of the following hull units. Which hull unit to choose depends on the size of your vessel and your operational requirements.

The hull unit provided with the Simrad MF90 system is designed to lower the transducer down below the ship's hull when the MF90 shall be used. When the MF90 is turned off, the transducer is hoisted for protection.

The illustrations are not to scale.

MF90: MF94:
Simrad MF90 Hull Unit Simrad MF94 Hull Unit

(A) Hand crank for manual hoisting and lowering
(B) Transducer cable with a plug that connects to the Transceiver Unit
(C) Hoist motor
(D) Motor Control Unit
(E) Transducer shaft
(F) Transducer shaft sleeve
(G) Mounting flange
(H) Installation trunk (not a part of the hull unit)
(I) Transducer

The Simrad MF90 sonar system can be provided with one of the following hull units.

Simrad MF90 choice of hull units

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 purpose of the Motor Control Unit is to control the hoisting motor on the hull unit. When you make the appropriate commands on the 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.

If you forget to hoist the transducer before the sonar is turned off, the transducer is hoisted automatically before the power is disconnected. The transducer is also hoisted automatically if a serious malfunction occurs in the communication between the bridge and the hull unit.

Caution: If the transducer hits larger objects or the bottom, the transducer shaft may be bent, or - in the 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's stability, you must have a water pump and a warning system in the sonar room.