Autonomous boats without GPS

Autonomous boats have many names: roboats, unmanned surface vessels, unmanned surface vehicles, and self-steering boats. It is the same thing. Autonomous robots are simply a variant of autonomous robots operating on the water’s surface.

There are many use cases for autonomous boats:

  • Delivering goods and passengers
  • Navigating channels and harbors for inspections
  • Patrolling
  • Autonomously docking to larger ships, for example, after performing a rescue operation
  • Using underwater sonars for underwater inspections and object detection

We focus on autonomous boats without GPS – not on maritime ships or large vessels. The article below discusses self-steering boats working in channels, tunnels, indoors, and underground – in any GNSS-denied areas – not in the open sea or lakes with easy positioning and navigation using GPS.

Example of precise tracking of racing boats without GPS

How autonomous boats work

Autonomous boats like autonomous robots or self-driving cars rely on several key systems to be autonomous:

  • Localization
  • Obstacle detection and avoidance
  • Mobility or propulsion

Since crewless surface vehicles interact with the world and users and perform some practical tasks; they also have to be capable of the following:

  • External communication and connectivity
  • User interface
  • Payload carrying capability

Autonomous boats get tasks from the end users or operators or larger ships and perform their tasks autonomously based on the localization systems and obstacle detection and avoidance systems. They rely on the controllers and processors, memory, and programs to operate with the rules. They are indeed simply a subset of autonomous robots.

Thus, like any autonomous robot, autonomous boats have sensors, processors, and actuators.

Self-steering boats are typical autonomous robots but on the water surface.

There are many other ways for localization, for example, LIDARs. But those are not recommended for the boat positioning because:

  • Expensive
  • Don’t work well in fog or rain
LIDARs are helpful for obstacle detection – not for positioning

Cameras seem to be better than LIDARs, in theory. But in practice, still, robust and precise positioning based on cameras is very challenging to implement, and their performance is heavily affected by lighting conditions, water reflections, fog, and rain.

Therefore, for autonomous boats in GNSS-denied areas, we recommend external RTLS systems such as Marvelmind Indoor “GPS” or UWB as the primary positioning source. The best performance is usually provided, but a sensors fusion approach is.


When GPS/GLONASS/Galileo/Beidou is available, navigation of autonomous boats is a relatively straightforward task, particularly when some flavors of RTK GPS are available. But it is a significantly more challenging task in GPS/GNSS denied areas, for example:

  • Channels surrounded by tall buildings
  • Tunnels
  • Closed viaducts
  • Under the bridges
  • Underground

Even when GPS is available, RTK GPS is not available, but an autonomous boat must dock with a moving ship.

Another type of problem arises when several boats must move in sync close to each other, maintaining the distances, like swarm boats.


The solution is a real-time locating system (RTLS) or indoor positioning system (IPS), for example, Precise Indoor “GPS” by Marvelmind.

Don’t be confused with the word indoor. If it is indoors, it can work indoors and outdoors. But most outdoor navigation systems, for example, GPS, can’t work indoors because GPS satellites’ radio signal doesn’t propagate through walls or ceilings.

How RTLS for self-steering boats work

Navigation for autonomous boats without GPS relies on one of the types of real-time locating systems (RTLS). Such a system doesn’t substantially differ from a similar RTLS system for autonomous robots or AGVs.

The RTLS consists of three main elements:

  1. Stationary beacons (anchors) – the equivalent of GPS satellites. They are used as coordinate reference points for positioning
  2. Mobile beacons installed on the boat
  3. Modem/router – a central device to control the system and to get the location data of the boat in one place – ground stations in GPS

Self-steering boats can get location data, including gyro and accelerometer data, from an inertial measurement unit (IMU) directly from the mobile beacon.

Or they can be remotely controlled by an external brain getting their location and IMU data via the modem – the system’s central controller. Though the self-steering boats will be remotely controlled, it doesn’t make them non-autonomous. They will remain autonomous. Their central controller will be outside of their main body.

Quick and dirty recommendations on configurations

If mobile beacons are NOT exposed to water or dust, or mist:

In this case, tracking boats is not different from the tracking robots/AGVs/vehicles in 2D. Check the Robotics page for more details. In short:

  1. Starter Set Super-MP-3D – the simplest and the most versatile set to start with
  2. Starter Set Super-MP-3D + Super-Beacon – if you want Location+Direction
  3. Starter Set Super-MP-3D + Super-Beacon + 2 x Omni-Microphones – if your area is large (20x20m or more) or your stationary beacons are 30 degrees from the horizon or lower. You will be able to build robots with this kind of driving capabilities

If mobile beacons are exposed to water or dust, or mist:

Then, the recommended configurations are the same, but the mobile beacons shall be Super-Beacons-Outdoor – they are IP protected.

In some cases, even more, protected and rigid Industrial Super-Beacons are recommended.

Customized configurations

For the most recommended configuration for your particular case with your specific requirements, please email us at

Autonomous boats vs. other types of autonomous robots

Autonomous boats vs. autonomous wheeled robots/AGVs:

  • Both types operate primarily in 2D
  • There are typically more obstacles and obstructions for the wheeled robot
  • The wheeled robot has an odometer as an additional source of location information
  • Water is a severe hazard to electronics – more problematic for boats. Saltwater is even more dangerous

Autonomous boats vs. autonomous drones:

  • It is easier for the boat because it is 2D
  • There is typically less obstruction
  • Drones fall. Boats sink. Still, a drone’s life is more dangerous and generally short
  • Boats can stay autonomous much longer than drones because of batteries and energy supply in general

"Lie, fishing stories, election promises, statistics, and IPxx" - be realistic

Remember that the right level of ingress protection guarantees that the devices won’t be killed with a short time of exposure to water or rain splashes. The IPxx certificate doesn’t say anything about prolonged exposure or exposure to something that is not clean, fresh water, for example, dirty, oily, salty water, snow, etc.

Yes, the IPxx devices will likely survive those exposures as well. But no guarantees. That is an open secret with all IPxx fine prints. Be aware and be realistic with expectations.

What to do?

  • Clean with fresh water after use so that dirt or salt, or similar pollutants wouldn’t destroy the protective membranes
  • Make sure that ice or frost won’t puncture the membranes. Don’t let the water freeze on the beacons
  • For long-time exposure to rain, use special umbrellas – similar to outdoor cameras. Maintain a line of sight to stationary beacons
  • The outdoor beacons can withstand rain exposure or water splashes, but the tracking performance is not guaranteed. The devil is in detail
  • After assembly, cover all metal parts with special saltwater-protecting lacquer. Remember not to spray over the membranes

If anything is unclear, contact us via