Simrad SU90 Hull units

The Simrad SU90 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 the operational requirements.

  • Simrad SU92 (standard) lowers the transducer 1.2 meters below the ship's hull. Maximum vessel speed is 21 knots.
  • Simrad SU93 lowers the transducer to 1.6 meters below the hull. Maximum vessel speed is 18 knots.
  • Simrad SU94 lowers the transducer to 2.1 meters below the hull. The maximum speed with the transducer fully extended is 11 knots. The speed can be increased with the transducer placed in its "middle" position.

Each hull unit (except SU94) can be supplied with a 4.6 or 7 m transducer cable. The SU94 is only supplied with a 4.6 m transducer cable.


(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 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.