How Often Does AIS Update Vessel Positions?
When people track ships online, one common question always comes up: How often does AIS update vessel positions? At first, vessel movements may seem slow or delayed on a MarineRadar map. However, once you understand how AIS works, everything starts to make sense.
In simple terms, AIS does not update every ship at the same speed. Instead, it adjusts automatically based on a vessel’s motion and location.
What Is AIS, and Why Does It Matter?
AIS, or the Automatic Identification System, is like a digital voice for ships. Every AIS-enabled vessel regularly sends signals that include its location, speed, direction, and identity.
Coastal stations and satellites pick up these signals. After that, MarineRadar platforms display the information on live maps. This allows users worldwide to view ships in real time.
How Often Does AIS Update Vessel Positions?
The update rate depends mainly on vessel speed and movement. Below is a simple breakdown:
- Fast-moving ships (over 14 knots): Updates every 2 to 10 seconds
- Slow-moving ships: Updates every 10 seconds to 3 minutes
- Ships at anchor or docked: Updates every 3 minutes.
- Ships changing course: Updates more frequently during turns
What Makes AIS Updates Different for Each Ship?
Although it may seem confusing at first, this flexible system is intentional. AIS conserves bandwidth while still providing accurate tracking.
Several factors influence how AIS updates vessel positions:
1. Vessel Speed
The faster a ship moves, the more often it broadcasts its location. This helps nearby vessels react quickly.
2. Course Changes
When a ship turns, AIS increases update frequency. As a result, direction changes appear smoother on radar maps.
3. Ship Status
Anchored or docked vessels don’t need constant updates. Therefore, their AIS messages are sent less frequently.
4. Signal Coverage
Near coastlines, AIS data is refreshed quickly. However, in open oceans, satellite-based AIS may update less often due to coverage limits.
How Does the MarineRadar App Handle AIS Updates?
The MarineRadar app and website don’t create AIS data. Instead, they receive, process, and display it.
When AIS updates vessel positions regularly:
- Movement appears smooth
- Speed looks accurate
- Direction changes are clear.
On the other hand, when updates slow down:
- Ships may seem to jump forward
- Speed may look outdated.
- Position updates may pause briefly.
Despite this, the platform displays the most recent received time, so users know how fresh the data is.
Are AIS Update Delays a Problem?
In most cases, no. Short delays are entirely expected.
For example:
- A ship in mid-ocean may update less often
- The weather can temporarily affect signal quality.
- Satellite refresh cycles can create small gaps.
However, this does not mean the vessel has stopped or disappeared.
When Should You Pay Attention to AIS Delays?
Although delays are common, some situations deserve attention:
- No update for several hours near the coast
- Sudden loss of signal in busy shipping lanes
- Unchanging speed or direction for long periods
Even then, these issues usually resolve once the vessel transmits again.
Why Understanding AIS Updates Helps You Track Better?
Once you understand how AIS updates vessel positions, tracking becomes less confusing and more reliable.
You can:
- Interpret ship movements accurately
- Avoid assuming technical errors.
- Trust the system during slow updates.
Conclusion
AIS is an adaptive system designed for safety and efficiency. Instead of constantly updating every ship, it adjusts based on current conditions.
By understanding how often AIS updates vessel positions, you can track ships with clarity, patience, and confidence.
Download Marine Radar: Vessel Tracker from the Google Play Store or App Store today and experience real-time ship tracking.
FAQs
Q: Does AIS update vessel positions in real time?
Yes, but “real time” varies by ship speed, movement, and location.
Q: Can weather affect AIS updates?
Yes. Heavy rain, storms, or interference can slightly delay transmissions.
Q: Do all ships use AIS?
Most commercial vessels do, but some small or military ships may limit transmissions.
