USER & INSTALLATION MANUAL
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7
extended navigation & communication
ExNC
extended navigation & communication
ExNC
4 What is AIS
The Automatic Identification System is a short range VHF based system used on
ships and by Vessel Traffic Services (VTS) for identifying and locating vessels by
electronically exchanging data with other nearby ships equipped with AIS and VTS
base stations operated by authorities. The range of your AIS system is depending on
various factors like the height of the VHF antenna mounted, weather conditions, etc.
In general the coverage can be up to 25 miles.
AIS is intended to enhance safety for life at sea, improve safety and efficiency in
navigation and protect the marine environment by assisting the vessel's watch
standing officers.
The information (data) AIS is exchanging consists basically of 3 types:
• static data: these data have been programmed to your AIS during installation
o MMSI,
o call sign,
o name of your vessel,
o length and beam + reference for position.
These data are fixed and needs to be changed only when your vessel
changes flag, name or its size during refit.
• dynamic data: these are deriving from your GNSS system or sensors (e.g.
Gyro) and calculated by your AIS transponder:
o Position,
o SOG,
o COG,
o navigational status (entered manually),
o UTC.
• voyage related data: are entered manually (only for AIS class A systems) and
do not apply for class B AIS transponders.
All these data can be displayed on a PI like PC, ECDIS, ENC.
The 4 “s”:
AIS is used in a ship-to-ship mode for collision avoidance and safety awareness.
Due to the limitations of VHF radio communications, and due to the fact that not all
vessels are equipped with AIS, it does not replace proper lookout. It is a supporting
tool only!
AIS is used in a ship-to-shore mode as a means for littoral States to obtain
information about vessel sailing its territory. VTS are operating AIS land stations to
monitor their area and for traffic management
SAR operators are using AIS to identify relevant vessels and their status.
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