The Automatic Identification System (AIS) is a technology that enables communication at sea. It works by using transponders installed on vessels. The vessels transmit and receive data automatically. Transponders on board a ship send automatically to other ships and shore authorities information such as the ship’s name, position, course, and speed. The broadcasts are made via VHF radio. The main purpose of the technology is to enhance maritime safety, mainly by avoiding collisions and improving the efficiency of vessel traffic services.
AIS Components
The transponder sends and receives data. There are two types of AIS transponders: Class A and Class B. Class A, which is required for commercial shipping, has more powerful and higher-frequency transmissions. Class B, which is aimed at small recreational vessels, gives sufficient information for most boating activities.
An AIS transponder works only if there is a GPS signal of sufficient accuracy. This is important because it allows the vessel’s position to be determined correctly, enabling accurate location data to be sent to other ships and stations.
AIS messages are sent through VHF radio frequencies, so data transmission and reception need an antenna. In general, the range is confined to line-of-sight, which might differ with the height of the antennas.
For a better understanding of the AIS data, it is very important to have a Display Unit or Chartplotter. Most seafarers connect AIS to an on-board chartplotter, giving a visual picture of the movements and locations of other vessels in the vicinity.
Why Recreational Sailors Should Consider AIS
One very important benefit of the AIS system is safety. The mere ability for other vessels to see you on their AIS will greatly reduce the chances of accidents. This is especially true in busy or low-visibility situations. Most AIS transponders provide collision alarms, which means you’ll be notified if you’re heading for a collision with another boat.
AIS gives you a real-time picture of the vessels close around you and helps you find way through busy channels or safely proceed past ships in open waters. This can be very important information when sailing at night or in foggy conditions, where visibility is limited.
It can sometimes be daunting to interact with other vessels, especially when you’re unsure of another ship’s intentions or course. With AIS, simply knowing the name and type of nearby vessels will already make it simpler and more effective to communicate via VHF radio.
In the unfortunate event of an accident or emergency, AIS can be pivotal in search and rescue operations. Your last known position will be precisely tracked by the authorities, which will thus achieve the first step of the search more quickly and improve the chances of a successful rescue.
Assisting to some extent in route planning and obstacle avoidance, AIS data can enable you, for example, to choose a way that will not cross traffic lanes, fishing zones, or other potentially troublesome areas.
Choosing the Right AIS System for Your Sailboat
Although Class A systems offer increased transmission frequency and higher power output, they are generally too much for recreational use and cost more. Class B systems, which are just fine for leisure sailors, are less expensive and address the needs of most non-commercial vessels.
You may wonder whether you need a transponder or if it’s just fine to have a receiver-only system. Because a transponder is actively sending and receiving information, it’s the best choice for sailors who are on the sea in busy or highly trafficked areas. If you’re mainly interested in seeing other vessels without sending out your own position, then an AIS receiver is a cheaper way to go.
Sailors have different opinions on the use of AIS — some like to have separate units, while others prefer all-in-one systems. It’s mostly a matter of taste and available area. For the most complete experience, choose a solution that will link with current navigation devices, such as chart plotters or multifunction displays.
Try to find a system that’s straightforward to install and has a simple user interface. A long, drawn-out setup process or overly difficult controls could make using the technology challenging and discourage you from doing so.
Effective Use of AIS
Your transponder must be working properly for it to be useful. Check your system regularly, making sure you have a strong GPS signal and that your VHF antenna is in good shape.
Chartplotters that display AIS data typically use particular symbols in their pictorial format to indicate various types of vessels or statuses, such as “moving” or “anchored.” Learn these symbols so you can easily interpret the information presented to you.
Collision alarm features are included in the majority of AIS devices. One might feel inclined to mute the alerts during peaceful sailing. It’s better to keep them on, as they may provide necessary warnings, particularly in busy waters.
Some sailors feel uneasy about transmitting their boat’s position at all times. A number of AIS transponders include a “silent mode,” which allows receiving information without transmitting one’s own position. Use this mode when privacy is paramount, but always remain alert and consider turning it off in busy shipping areas.
Prior to departure, employ your AIS system to plot a precise course for the intended track with prominent safety in mind. Avoid obstacles and areas with heavy traffic. By doing so, you will enhance the ease and reduce the stress of your journey.
Remember the weather — is a significant factor in safe sailing. Have access to good weather information and include it in your planning and decision-making process while on the water.
Integrating AIS with Other Navigational Tools
Digital charts integrated with AIS will show the positions of vessels in real time. Right on your electronic map, you will see live traffic information superimposed clearly.
The combination of AIS with radar systems gives you an all-encompassing view of the surroundings. While AIS supplies information about vessels in detail, radar can detect other impediments in the water, such as landmasses or smaller craft that do not transmit AIS signals.
By connecting your AIS data with an autopilot system, you can enhance safety by changing the course when there are vessels detected. This is particularly helpful in open waters.
Today, many apps allow the viewing of AIS data on smartphones or tablets. You can stay aware of your surroundings, even when you’re away from the primary helm station.