IMO Performance Standards for Echo Sounder

As per Chp V/ Reg 19.2.3 of SOLAS 73/78, An Echo Sounder is required onboard ship which should provide reliable information on the depth of water under a ship to help in navigation.

Echo Sounder

SOLAS Chp V/ Reg 19.23:

All ships of 300 GRT and above and passenger ships irrespective of size shall, in addition to a spare Magnetic Compass and a daylight signalling lamp, be fitted with an Echo Sounding Device, or other electronic means, to measure and display the available depth of water

SOLAS Echo Sounder Requirement

This aforementioned equipment should comply with the performance standards of Echo Sounder mentioned in Resolution A.224(VII) of IMO adopted in Oct 1971. These Performance Standards got revised under Annex IV of Resolution MSC. 74 (69) which were adopted in May 1998.

The revised Performance Standards are as follows:

1. Range of Depths

  • Under normal propagation and sea bed reflectibility conditions, the equipment should be capable of measuring any clearance under the transducer between 2 meters and 200 meters.

2. Range Scales:

  • The equipment should provide a minimum of two range scales one of which, the shallow range, should cover a range of 20 m, and the other, the deep range, should cover a range of 200 m.

3. Main Display:

  • The primary presentation should be a suitable graphical display which provides the immediate depth and a visible record of soundings. The displayed record should show at least 15 min of soundings.

3.1 Other Displays

  • Other forms of the display may be added but these should not affect the normal operation of the main display.

4. Pulse Repetition Rate

  • The pulse repetition rate should not be slower than 12 pulses per minute on the deep range and 36 pulses per minute on the shallow range.

5. Roll and Pitch

The performance of the Echo Sounder should be such that it will meet the requirements of these performance standards when the ship is rolling ±10° and/or pitching ±5°.

6. Multiple Installations

  • More than one transducer and associated transmitter-receiver may be fitted.
  • If more than one transducer is used:
    • means should be available to display the depths from the different transducers separately, and
    • a clear indication of the transducer(s) in use should be provided

7. Data Storage

  • It should be possible to record on paper recording or other means the information about:
    • the depth(s), and
    • the associated time for 12 h.
    • There should be a means to retrieve the recorded information.

8. Accuracy of the Echo Sounder

8.1 Accuracy of Measurement:

  • Based on a sound speed in water of 1,500 m/s, the tolerance of the indicated depth should be either:
    • ± 0.5 m on the 20 m range scale, respectively ±5 m on the 200 m range scale; OR
    • ± 2.5% of the indicated depth, whichever is greater.

9. Discrimination

The scale of the display of the Echo Sounder should not be smaller than 5.0 mm per meter depth on the shallow range scale and 0.5 mm per meter depth on the deep range scale.

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10. Malfunctions, Alarms, and Indications

10.1 Depth Alarm:

An alarm signal- both visual and audible with mute function – should be provided when the water depth is below a preset value.

10.2 Failure or reduction in power supply

Alarm signals, both visual and audible (with mute function) to the OOW should be provided to indicate failure or a reduction in the power supply to the echo sounder which would affect the safe operation of the equipment.

11. Ergonomic Criteria

11.1 Operational Controls

  • The function of range scale selection should be directly accessible.
  • The settings for the following functions should be recognizable in all light conditions:
    • range scale; and
    • preset depth alarm.

11.2 Presentation of Information

  • Marks: The graphical display should be capable of showing:
    • the depth marks at intervals not larger than one-tenth of the range/scale in use; and
    • time marks at intervals not exceeding 5 min.
  • Paper Recording: If the paper is used for recording either by marks on the recording paper or by other means, there should be a clear indication when the paper remaining is less than 1 m.

11.3 Interfacing with Echo Sounder Equipment

  • Output(s) should be available from which depth information may be supplied to other equipment such as remote digital displays, voyage data recorders, and a track control system.
  • These outputs should be digital, serial communication, facilities which should comply with the relevant international standards

Design and Installation of the Equipment

The equipment should comply with IMO resolution A.694(17).

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