System diagram

The Simrad CS90 comprises a Processor Unit (computer) with an operating panel, a transceiver and a hull unit with the transducer.


(A) Display  (the second display is optional)
(B) Processor Unit (computer)
(C) Operating Panel
(D) Transceiver Unit
(E) Hull Unit
(F) Transducer

The cable between the wheelhouse units and the CS90 Transceiver Unit in the sonar room must be a high-quality Ethernet cable. This cable can be purchased locally, or ordered from us.

Processor Unit

The Processor Unit comprises a single powerful maritime computer. It is provided as a standard part of the delivery. It serves several functions.

The Processor Unit handles the advanced signal processing required to present the information on the display, and it allows you to control the sonar. It provides the graphic presentation of the sonar views and the images that are created, it holds the menu system, communicates with the transceiver circuitry, and reads information from the peripheral units. The computer is based on a commercial design, but the software and hardware have been specified and assembled specifically to meet the sonar requirements.

Operating Panel

The Operating Panel allows you to access to the most frequently used functions in a fast and efficient manner. It also provides a trackball and the necessary control buttons to operate the menu system.

Transceiver Unit

The Transceiver Unit contains the transmission and reception circuitry for the sonar. The cabinet is by default fitted with a heat exchanger. This means that a stable internal temperature and humidity are ensured independently of the sonar room environment. It will also prevent dust particles from contaminating the electronic circuitry.

The connections for power and communication are made under the cabinet. The transducer cable is connected using a large proprietary plug on the side wall.

The Transceiver Unit has been designed to be mounted on the bulkhead. It is fitted with powerful shock absorbers to withstand the violent motions of a vessel at sea.

Hull unit

The hull unit is designed to lower the transducer down below the ship’s hull when the sonar system shall be used. When the sonar is turned off, the transducer is hoisted for protection.

The hull unit is a 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.

Hull units for the Simrad CS90 Fish finding sonar

Hull unit Lowering depth Transducer cable Maximum speed
CS90 1 m 4.6 or 10 m 20 knots
CS94 2.1 m 4.6 or 10 m 19 knots

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.