GMDSS AND BRIDGE EQUIPMENT

Global Maritime Distressand Safety System

(GMDSS)

ByManish MalgaonkarETO, 9th Batch, ET278

General Overview

• The GMDSS makes specific requirements with regard to radio equipment, and ships must be able to carry out several different functions, one of which is the ability to TRANSMIT and RECEIVE Maritime Safety Information (MSI).

General Overview• The fundamental difference between the old and the new

distress system is that the new system is shore centred/coordinated and moves emphasis from ship to ship alerting to ship to shore alerting.

• The new system is quicker, simpler and, most importantly, more efficient and reliable than the old manual Morse Code and radiotelephone alerting system.

• GMDSS is specifically designed to automate a ship’s radio distress alerting function, and consequently, remove the requirement for manual (human) watch-keeping on distress channels.

During Olden Days

GMDSS CONCEPT

Types of Distress

1. Distress alerting – Ship to shore• EPIRB• Digital Selective Calling (DSC) • INMARSAT

2. Distress alerting – Shore to ship

3. Distress alerting – Ship to ship

4. Search and Rescue Co-ordinating Communications

5. On-Scene Communication

6. Locating

7. Transmission/Reception of Maritime Safety Information

8. General Radiocommunications

NAVTEX

NAVTEX• Navtex (Navigational Telex) is an international

automated medium frequency direct-printing service for delivery of navigational and meteorological warnings and forecasts, as well as urgent maritime safety information to ships.

• Navtex was developed to provide a low-cost, simple, and automated means of receiving this information aboard ships at sea within approximately 370 km (200 nautical miles) off shore.

• There are no user fees associated with receiving navtex broadcasts, as the transmissions are typically transmitted from the National Weather Authority (Italy) or Navy or Coast Guard (as in the US) or national navigation authority (Canada).

EPIRBEmergency Position Indicating Radio Beacon


• The 406 MHz satellite EPIRB transmits a 5W radio frequency (RF) burst of approximately 0.5s duration every 50 seconds.

• Improved frequency stability ensures improved location accuracy, while the high peak power increases the probability of detection. The low duty cycle provides good multiple-access apability, with a system capacity of 90 activated beacons simultaneously in view of the satellite, and low mean power consumption.


• An important feature of the new satellite EPIRB is the inclusion of a digitally encoded message, which may provide such information as the country of origin of the unit in distress, identification of the vessel or aircraft, nature of distress and, in addition, for satellite EPIRBs code in accordance with the maritime location protocol, the ship's position as determined by its navigation equipment.


• Satellite EPIRBs are dual-frequency 121.5/406 MHz beacons. This enables suitably equipped SAR units to home in on the 121.5 MHz transmission and permits over flight monitoring by aircraft.

• Depending on the type of beacon (maritime, airborne or land), beacons can be activated either manually or automatically.

Search and Rescue Radar Transponders (SARTs)


• Search and rescue radar transponders (SARTs) are main means in the GMDSS for locating ships in distress or their survival craft, and their carriage on board ships is mandatory.

• The SART operates in the 9GHz frequency band and generates a series of response signals on being interrogated by any ordinary 9GHz shipborne radar or suitable airborne radar.


• No modification is needed to a ship's radar equipment for detecting SART signals.

• SARTs can be either portable, for use on board ship or carrying into any survival craft, installed on the ship and in each survival craft, or so as to operate after floating free from the sinking ship. They may also be corporated into a float-free satellite EPIRB.


• The SART can be activated manually or automatically when placed into the water so that it will thereafter respond when interrogated.

• When activated in a distress situation the SART respond to radar interrogated by transmitting a swept-frequency signal which generates a line of blip code on a radar screen outward from the SART’s position along its line of bearing. This unique radar signal is easily recognized on the radar screen and the rescue vessel (and aircraft, if equipped with suitable radar) can detect the survivors even in poor visibility or at night.


• The SART provides a visual or audible indication of its correct operation and will also inform survivors when it is interrogated by a radar.

• The SART will have sufficient battery capacity to operate in the stand-by condition for 96 hours and 8 hours in the transmission mode and will be able to operate under ambient temperatures of -20°C to +55°C.


• The vertical polar diagram of the antenna and the hydrodynamic characteristics of the device will permit the SART to respond to radar under heavy swell conditions. SART transmission is substantially omni directional in the horizontal plane.

INMARSAT-FLEET 77

INMARSAT-FLEET 77

In response to the ever increasing need for computer-based, cost effective and secure communications system at sea, Inmarsat has developed advance computer solutions that deliver content-rich data and communications solutions to ships of all sizes: INMARSAT Fleet.

• Fleet F77• Fleet F55• Fleet F33

INMARSAT-FLEET 77

• The Fleet F77 system is based on digital technology• Can supply digital communication via telephony, fax,

mobile ISDN and Mobile Packed Data Service (MPDS)

INMARSAT-FLEET 77

SATCOM C• Inmarsat-C is a two-way, packet data service operated by the

telecommunications company Inmarsat which operates between mobile earth stations (MES) and land earth stations (LES).

• It became fully operational after a period of pre-operational trials in January 1991.

• The advantages of Inmarsat-C compared to Inmarsat-A are low cost, smaller and uses a smaller omni-directional antenna.

• The disavantages is that voice communication is not possible with Inmarsat-C.

• The service is approved for use under the Global Maritime Distress and Safety System (GMDSS), meets the requirements for Ship Security Alert Systems (SSAS) defined by the International Maritime Organization (IMO) and is the most widely used service in fishing Vessel Monitoring Systems (VMS).

SATCOM C

SATCOM B

• Voice at 16.0 kbps.• Fax at 14.4 kbps.• Data at 9.6 kbps.• High-speed Data (HSD) at 64/56 Kbps.• Video conferencing.• GMDSS

SATCOM B• Even in the most remote locations, the superior Inmarsat B service

from Stratos offers a comprehensive, fully digital communications package designed for applications such as video conferencing, Internet access, voice and Telex services, as well as fax and data transmission.

• The Inmarsat B system, which continues to be extremely popular with the maritime community, provides separate channels for voice, telex, fax and data, as well as Stratos' 64 kbps high-speed data (HSD) option, which make it an advantageous choice for high-volume satellite communications users. Transportable terminals are the size of a small suitcase and weigh 15-20 kg. Maritime terminals have radomes 1.0-1.2 m in height and weigh 60-70 kg.

Bridge Equipment

Automatic Identification system

• AIS is a system which helps to pinpoint the location and other navigational statistics of ships. AIS uses VHF radio channels as transmitters and receivers to send and receive messages between ships which endeavors to fulfill a lot of responsibilities.

Long Range Tracking and Identification (LRIT) System

• RIT is an international tracking and identification system incorporated by the IMO under its SOLAS convention to ensure a thorough tracking system for ships across the world.

Rudder Angle Indicator

• Rudder angle indicator, as the name indicates, provide the angle of the rudder. The display is provided on bridge to control the rate of turn and rudder angle of the ship.

Voyage Data Recorder• A VDR or voyage data recorder is an instrument safely installed on a ship

to continuously record vital information related to the operation of a vessel. It contains a voice recording system for a period of at least last 12 hours. This recording is recovered and made use of for investigation in

events of accidents.

Rate of turn indicator

• It indicates how fast the ship is turning at steady rate, normally shown as number of degree turned.

GPS Receiver• A Global Positioning System (GPS) receiver is a display system used to

show the ship’s location with the help of Global positioning satellite in the earth’s orbit.

http://www.marineinsight.com/marine-navigation/revolutionising-marine-travel-marine-vhf-radios-marine-gps-and-marine-autopilots/

Sound Reception System• This system is required for a ship with fully enclosed type bridge. It

enables the navigating officer inside the cabin to listen to the sound signals and fog horn from other ships.

GMDSS AND BRIDGE EQUIPMENT

Engineering

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