Take 10: Issue 34

28 Sep 2023 The Navigator

AIS is a hugely important tool for vessel safety and navigation, and its evolution is both rapid and ongoing. Here are ten important things to remember about AIS.

1 AIS transformation

AIS has been a transformative technology, both as a tool to help identify risk of collision but also aiding security and logistics.

2 Strengths

AIS is a powerful tool that allows ships to be better identified and seen in poor visibility or behind land. It is particularly useful when combined with radar and visual observations

3 Weaknesses

AIS is completely reliant on GNSS (GPS) and VHF, so any disruption to those systems will affect it. The quality of AIS transmission depends on the accuracy (or not!) of manually entered data.

4 Beware over reliance

Navigators should never solely rely on AIS for making critical decisions. Remember that Rule 5 of the Colregs requires the use of all available means to assess collision risk.

5 What else is out there?

AIS is only mandatory for vessels of 300GT on international voyages. This means that many smaller vessels, including fishing boats and leisure craft, may not appear. Other navigation hazards, such as rocks and beacons that will be seen by radar or visually, will not be picked up by AIS.

6 Search and rescue

The range of AIS is much greater than radar. It can be detected up to 60NM away, and can play a vital role in search and rescue operations.

7 The off switch

AIS can be turned off with the explicit permission of the Master. Traditionally, this would be in the case of a security threat to the vessel. However, we are seeing more and more occasions of AIS being turned off simply to make it harder to track vessels and their operations.

8 Looking ahead

There are a number of AIS tracking websites available. These can be very useful for looking ahead, identifying congested areas and assisting with passage planning

9 Into the future

The evolution of AIS is driven by technological breakthroughs. Satellite-AIS has remarkably expanded its operational extent. VHS Data Exchange System (VDES) is also emerging as the next evolutionary step, described as AIS 2.0.

10 Information sharing

When you have an opportunity, discuss with your bridge team how they use AIS and debate its pro and cons. Help new officers fully understand the strengths and weaknesses of AIS.

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