Live tracking vs AIS, and how geofence alerts fit in
AIS tells you about vessels around you; live tracking tells chosen people where you are. What each is for, when to use both, and how to set up geofence alerts that actually help on the water.
By the Waterspeed team
AIS and live tracking both put positions on a map, so they are often confused. They answer different questions.
What AIS is designed to do
AIS (Automatic Identification System) is a radio system vessels use to broadcast identity, position, course and speed. Commercial ships generally must carry Class A equipment; many leisure boats use Class B transceivers, and some only carry receivers. It’s about collision awareness: what’s around you, where it’s going and how fast. Apps such as MarineTraffic show AIS data online.
What live tracking is designed to do
Live tracking takes a GPS position from your phone, watch or device and shares it over an internet connection (usually cellular) with people you choose. It’s personal: where you launched, where you are now, how your session is going. See Live tracking on the water.
The core difference
AIS tells you about vessels in the traffic around you. Live tracking tells chosen people about you.
- AIS matters most when the risk comes from other vessels: crossing near commercial routes, racing near a shipping lane, a support boat keeping an eye on a race course.
- Live tracking matters most when the question is “where is my person?”: solo sessions, long routes, group rides that spread out, youth training, unfamiliar spots, events where organisers want a real-time view.
Note that a board, wing or kite rider won’t usually appear on AIS at all, and live tracking won’t warn you about a ship. For many sailors and riders, the answer is to use both, each for its own job.
Geofence alerts
A geofence is a virtual boundary on a map: a circle around your launch, a shape around a bay, a corridor along a course, or an area to avoid such as a channel, reef or restricted zone. When a tracked device enters, leaves or stays in that area, the system logs the event or sends an alert. Some tracking platforms and satellite messengers offer them.
Geofencing is an aid, not collision avoidance, navigation equipment or a substitute for local knowledge. GPS accuracy varies, batteries die and coverage drops.
How to set up a useful geofence
- Start with the risk, not the map. What are you trying to prevent or monitor? Drifting offshore in an offshore wind, entering a busy channel, a group spreading too far?
- Draw a boundary with a margin. Place it before the point where things get difficult, not on the hazard itself.
- Choose the trigger. An exit alert for the edge of your intended area; an entry alert when the zone itself is the concern (a restricted harbour section, shallow water, a boat channel).
- Pick recipients who can act: a trusted shore contact for a solo session, the coach boat or safety team for club training.
- Test it on land by walking or driving across the boundary with the same device and settings you’ll use on the water.
- Make it part of the briefing. Tell the group where the boundary is, who gets the alert, and how long to wait before escalating. An alert is a cue to assess the situation, not automatic proof of trouble.
Geofences for performance
Boundaries also make sessions repeatable: same reach, same start area, same training zone. On a windy lake, the direction of a run and distance from shore can say more than top speed; on an ocean foil session, separating the clean swell zone from the paddle-out gives fairer comparisons.
Every layer depends on the basics: a forecast check, telling someone your plan, the right gear and turning back when conditions change. See Watersports safety apps and tools.
