Class A vs. Class B AIS: Tracking Differences
The main difference between Class A and Class B AIS is the power and detail of their ship-tracking signals. Class A AIS is used by large commercial ships and sends stronger, faster, and more frequent updates. Class B AIS is mainly used by smaller boats and yachts and sends simpler updates at a slower rate.
Because of this, Class A ships usually appear more accurately and smoothly on ship-tracking platforms like MarineRadar. Meanwhile, Class B vessels may update less often and sometimes appear to “jump” on the map.
Let’s break it down in the simplest way possible.
What is AIS & Why Do Ships Use It?
AIS stands for Automatic Identification System. It is a tracking system used by ships to share their location. Ships send signals that include the position, speed, direction & ship name.
AIS is a mandatory maritime safety system regulated by the International Maritime Organization to improve navigation safety and collision avoidance. AIS helps ships avoid collisions, locate other ships, and improve safety at sea.
Maritime safety systems, such as AIS, are part of global shipping frameworks discussed by the United Nations Conference on Trade and Development.
What is Class A AIS?
Class A AIS is the strongest and most advanced type.
Who Uses Class A?
- Large commercial ships
- Cargo vessels
- Passenger ships
Large vessels must carry AIS equipment in accordance with regulations issued by the International Maritime Organization.
Features of Class A AIS
- High transmission power
- Frequent updates
- Very accurate tracking
- Sends a lot of data
It updates every few seconds.
What is Class B AIS?
Class B AIS is a simpler and lighter version.
Who Uses Class B?
- Small boats
- Fishing vessels
- Private yachts
Features of Class B AIS
- Lower transmission power
- Slower updates
- Less data sent
- More affordable
It updates less often.
Class A vs Class B AIS: Key Differences
Here is a simple comparison:
Feature | Class A AIS | Class B AIS |
Used By | Large ships | Small vessels |
Power | High | Low |
Update Speed | Very fast | Slower |
Data Detail | More detailed | Basic |
Accuracy | Very high | Moderate |
Cost | Expensive | Affordable |
Required by Law | Yes | No |
The International Maritime Organization defines AIS classifications and usage standards.
How This Affects Ship Tracking on MarineRadar
When you use MarineRadar, the AIS type affects what you see.
Class A Ships on MarineRadar
- Move smoothly on the map
- Update frequently
- Show detailed information
Very accurate tracking.
Class B Ships on MarineRadar
- Update less often
- May “jump” on the map
- Show limited details
Slightly less accurate.
Why Class A is More Accurate
Let’s keep it simple.
Class A sends:
- Signals more often
- Stronger signals
- More information
So tracking systems get better data.
Why Class B is Still Useful
Even though it’s simpler:
- It still shows the ship location
- Helps avoid collisions
- Works well for small vessels
It’s a cost-friendly option.
Example:
Let’s imagine two ships:
Big Cargo Ship (Class A)
- Sends updates every few seconds
- Strong signal
- Smooth movement on the map
Small Boat (Class B)
- Sends updates every few minutes
- Weak signal
- Movement may look jumpy
AIS Signal Frequency Explained
Here’s how often signals are sent:
- Class A → Every few seconds
- Class B → Every 30 seconds or more
AIS transmission intervals vary by vessel type and speed under guidelines from the International Maritime Organization.
Why Some Ships Are Hard to Track
Sometimes ships don’t appear correctly.
This can happen because
- Class B sends fewer updates
- Weak signals
- Long distance from land
Signal limitations and maritime tracking challenges are discussed in global shipping systems by the United Nations Conference on Trade and Development.
Satellite vs Coastal Tracking Impact
AIS signals are collected by:
- Coastal stations (near land)
- Satellites (deep sea)
Class A Works Better with Satellites
- Strong signals
- Easier to detect
Class B may struggle.
- Weak signals
- Harder to capture in the deep sea
Why IMO Requires Class A
The International Maritime Organization requires Class A for large ships because
- Safety is critical
- More passengers or cargo
- Higher risk at sea
How UNCTAD Supports AIS Systems
The United Nations Conference on Trade and Development highlights how AIS:
- Supports global trade
- Improves shipping transparency
- Helps monitor vessel movement
Conclusion
Now you know what AIS is, the difference between Class A and Class B, and how it affects ship tracking.
Class A = fast, powerful, accurate
Class B = simple, slower, affordable
With this knowledge, you can better understand what you see on MarineRadar.
FAQs
Q: What is the main difference between Class A and Class B AIS?
Class A is more powerful and accurate, while Class B is simpler and slower.
Q: Which AIS is more accurate?
Class A AIS is more accurate due to faster updates.
Q: Do all ships use Class A AIS?
No, only large ships are required to use it.
Q: Why do small boats use Class B AIS?
Because it is cheaper and easier to install.
Q: Does AIS affect MarineRadar tracking?
Yes, AIS type affects update speed and accuracy.