Answer
Long-Range Identification and Tracking (LRIT):
Purpose: LRIT is a global tracking system designed to monitor the movement of vessels over long distances. It is primarily used for security and regulatory compliance.
LRIT requires that all passenger ships including high speed craft, cargo ships of 300 gross tonnage and above, mobile offshore drilling units should automatically transmit every 6 hours the identity of the ship, the position
report and data and time of the position.
Key Features:
• Monitors the movement of vessels beyond national jurisdiction.
• Requires vessels to report their position at specific intervals.
• Ensures compliance with international maritime security regulations.
• Addresses security concerns by tracking vessels globally.
Automatic Identification System ( AIS ):
Purpose: AIS is a system used for ship-to-ship and ship-to-shore communication to enhance maritime safety and prevent collisions. It provides real-time information about a vessel's identity, position, course, and speed.
Mandatory by:- SOLAS , Chapter 5, Reg 19
AIS use by all vessels >500GT, for any vessel >300GT that is on an “international Voyage” and for all passenger vessels.
Key Features:
• Broadcasts essential information such as vessel name, MMSI (Maritime Mobile Service Identity) number,
position, speed, and course.
• Operates on Very High Frequency (VHF) radio frequencies.
Facilitates collision avoidance and aids in search and rescue operations. Mandatory for most commercial vessels above a certain size.
AIS vs LRIT
• Long Range identification and tracking // Automatic Identification system
• Purpose: Maritime Security and Awareness // Purpose: Navigation and Anti- collision tool
• All ships of 300 GT &above on international Voyages and all ships of 500GT on coastal Voyages are to be fitted
with LRIT // All ships of 300GT and above on international Voyages and all ships of 500 GT on coastal Voyages are to be fitted with AIS.
• LRIT works on satellite communication ie. Satellite based system // AIS works on VHF communication ie. VHF
based system
• NO fixed channel // AIS has 2 dedicated channels 87B & 88B
• Secure data // Public data
• Worldwide coverage available for LRIT ie. Near global coverage (INMARSAT)- Unlimited range // Coverage
for AIS is 35-40 nautical miles ie. Only where AIS coverage is provided
• Transmits position, IMO number, Date & Time // Transmits position, IMO number, Date & Time vessel type,
Speed, Course etc.
• Normal time interval every 6 hours, can be changed to minimum every 15 minutes or maximum 24 hours //
Time interval depends upon navigational status and speed of vessel.
• LRIT is connected to VDR and has inputs from GPS // AIS is connected to radar , ECDIS and VDR and has
inputs from GPS Gyro, ROTI, log
• Track & locate ship in long range // Track & locate ship in coastal waters
• LRIT is not an aid to navigation // AIS is an aid to navigation
• LRIT information is not available to vessels in the vicinity // AIS information is available to ships in
vicinity.
Voyage Data Recorder (VDR):
Purpose: VDR is a data recording system designed to collect and store data related to the operation of a vessel for accident investigation and analysis.
The primary purpose of a Voyage data recorder (VDR) or a simplified Voyage data recorder (S-VDR) is to maintain a store of information, in a secure and retrievable form, concerning the position, movement, physical status, command and control of a vessel over the period leading up to and following an Incident. This information is for use during any subsequent investigation to identify the cause(s) of the Incident.
IMO Requirements- All cargo ships over 3000 GRT constructed after 01 July 2002 and all passenger ships are required to be fitted with a Voyage Data Recorder (VDR).
Additionally, all cargo ships over 3000 GRT built before 2002 must be fitted with a VDR or a Simplified VDR (S-VDR). All VDRs and S-VDRs are subject to an annual performance test, conducted by an approved servicing facility, to verify the accuracy, duration and recoverability of the recorded data.
Mandatory by:- SOLAS, CHAPTER 5, REG. 20
Key Features:
Records a variety of data, including audio from the bridge, radar information, speed, heading, and other Critical parameters.
Aids in accident investigation and reconstruction.
Enhances safety by providing insights into the vessel's operations.
*** In summary, AIS is primarily focused on real-time communication and collision avoidance, LRIT is a tracking system for long-distance monitoring, and VDR is a data recording system for post-Incident analysis and investigation.
While AIS and LRIT contribute to the safety and security of maritime operations, VDR plays a crucial role in understanding the circumstances leading to accidents or Incidents at sea.