Building an Autonomous Sailboat That Pursues to Cross the Atlantic Ocean

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The goal is to build a fully autonomous sailboat that will cross the Atlantic Ocean while following strict rules of the Microtransat Challenge – a transatlantic race for autonomous boats. According to the rules, the maximum length of the boat is limited to 2.4 metres and the target point across the ocean must be reached within 25 km radius. It's quite a challenge, isn't it?

Our first transatlantic attempt commenced on September 12, 2016. The boat was launched from Newfoundland and was expected to reach its final destination in Ireland.

The boat went through a series of troubles and automatic recoveries, so it was really exciting to watch the progress.

The name OpenTransat suggests that all the details including the code, schematics and actual build process will be revealed. Going open-source will definitely speed up the development of autonomous sailboats and help others build upon a proven concept. We are just at the beginning of a long, thrilling journey!

Track the Boat

There are three trackers which are located on the boat. One Iridium tracker (RockBlock module) which is represented by the green color, and two Globalstar trackers (SPOT Trace) which are identified by the red and yellow colors.

On the tracking map, you can also read comments with explanations and assumptions, outlining what could possibly create challenges. Is the boat mechanically damaged by a wild storm? Was it hit by a floating object? Hopefully, we will find the definite answers after the boat recovery and a thorough examination.

Track the boat here:

Launched from Newfoundland

The boat was shipped to Newfoundland in several packages and launched from a fishing boat about 5.5 km (3.4 miles) from the harbour. The route from Newfoundland to Ireland has been chosen as the shortest path across the Atlantic, and it's also in the direction of prevailing winds.

How It Works

The main framework is built from aluminum profiles on top of a surfboard, so the boat will never sink. The boat is balanced by a heavy keel that would flip the boat back over in case it flips. This concept has been chosen for its fast assembly and also because of the ability to make easy modifications. It's more like a proof of concept, with the purpose to test different hardware modules and navigation software before proceeding to a more streamlined design.

The sail is designed to resist high ocean winds. It is made from ripstop nylon that is reinforced by nylon webbing and thick carbon fiber tubes.

The electronics is securely sealed in a Pelican case and two polycarbonate cases. The Pelican case contains four LiFePo4 batteries, solar charge controller and an Arduino-based controller for navigation.

Satellite Communication

The Iridium satellite module, as well as GPS, is in a separate polycarbonate case for better signal reception. Another polycarbonate case contains a SPOT tracker and a GPS logger too.

You can find more about hacking SPOT Trace in the project log.


The video below demonstrates the rudder being turned by a servo when the compass is off-course.

The servo alone is said to be IP67 waterproof, but what if the boat encounters 5-meter waves? A few layers of latex gloves filled with a silicone grease were added for extra protection.


A Git2 action camera is recording a 15-second video every 30 minutes. The camera has been hacked to be powered by the primary battery source and controlled by Arduino.

The video is stored on a 128 GB SD card, and it can be accessed only when the boat is recovered because it is unrealistic to transmit any part of the video over a satellite network. Sending a single high-resolution image would cost hundreds of dollars, not to mention that the speed is significantly lower than dial-up.

What's next?

What comes after failure, is another trial. A new boat built from super-strong materials with radically improved hardware and software will be definitely more capable to cross the ocean. Stay tuned for the next transatlantic attempt in 2018!

  • The molds are ready!

    Andy Osusky03/12/2018 at 07:51 0 comments

    Check out a video how the molds were built from the plugs:

    Bottom part mold (hull)

    Top part mold (deck)

    Now it's time to build strong carbon/Kevlar parts using resin infusion.

  • Finished plugs!

    Andy Osusky03/01/2018 at 08:44 0 comments

    Check out a video how the foam plugs were built:

    Bottom part (hull)

    Top part (deck)

    The next step is building the molds.

  • Final 3D Design

    Andy Osusky12/05/2017 at 10:30 1 comment

    The design posted back in 2016 has now been improved in many aspects. It's more streamlined, balanced, robust and optimized for speed.

    This rudder combines two interesting features – avoids entanglement and reduces the power needed to steer the boat. 

    Here's how it's designed on the inside. The heavy duty aluminum skeleton holds all the critical parts together.

    From this point, it's going to be pretty straightforward. The next step is to make a foam hull using a CNC foam cutter and then build the molds.

  • Successful Lake Test

    Andy Osusky11/06/2017 at 13:28 0 comments

    The small-scale model from the previous log has been tested on a lake. Wow, this wingsail concept works incredibly well!

  • Small-Scale Prototype

    Andy Osusky10/16/2017 at 11:47 0 comments

    A small-scale prototype of the boat has been built to test and tweak the concept before spending a lot more time building the bigger boat for extreme ocean conditions. It's a close copy of the final design with the same hardware and navigation software. Here's the build progress.

    Carbon Fiber Hull

    Different techniques were evaluated to build these two carbon fiber parts. I will give more details when building the ocean-going boat.

    Filling with Foam

    The hull has been filled with a closed-cell polyurethane foam. The side floats were made from XPS foam wrapped with fiberglass.

    Joining and Painting

    The two parts of the hull were joined using a Kevlar tape and painted with a special antifouling paint. This kind of paint doesn't give as smooth finish as a gelcoat or normal paint, but it prevents subaquatic organisms from attaching to the hull.


    The rudder is made from carbon fiber, Kevlar and a steel rod.


    The keel is made from two threaded rods and a foam wrapped with fiberglass. Finally, the foam was dissolved with acetone to decrease buoyancy.


    The “bulb” is made from aluminum tube filled with lead and two 3D-printed plastic parts.

    Servo, GPS, Electronics Housing


    The battery provides enough power for 8 hours of continuous operation. 


    The wingsail is made from a foam wrapped with carbon fiber. This kind of sail works much like an airplane wing – it automatically maintains an effective angle of attack using the small "tail" behind the large wing. This concept is inspired by experimental work found on

    Finished Boat

  • Testing, Testing

    Andy Osusky10/05/2017 at 11:03 0 comments

      Every single component of the boat is thoroughly tested before implemented in the design. Here I will talk about the most important recent results.

      PID Controller Testing

      PID controller is a computer algorithm that takes into account immediate compass and position changes while steering, so the boat keeps its heading in a straight line.

      Stability at high speeds would be difficult to test with a sailboat as the winds in the middle of the ocean can be much stronger. Therefore, a hobby RC boat has been converted to autonomous boat to fine-tune the PID controller working at high speeds.

      Servo Testing

      The most common issue in the previous transatlantic attempts is rudder failure. If we expect a rudder moving every 3 seconds for a duration of 6 months, this makes over 2.5 million cycles! That's more than any servo manufacturer can guarantee (besides some very special and expensive products for medical applications).

      I have been testing a cheap worm drive sold as JGY-2838 connected to a magnetic encoder EMS22A as seen in the video below.

      It's loaded with weight to simulate water resistance. The motor made over 3 million cycles under decent load until it failed. You can see in the picture that the worm gear is completely worn off.

      It's not bad – it means about 7-9 months of continuous operation in the ocean which is more than the expected time frame (less than 3 months). There are two ways to improve it even further without much additional work:

      1. Add extra lubricant into the gearbox. Experts say that the worm won't wear off as long as it's properly lubricated. It starts to wear off very quickly after the lubrication fails.
      2. Steer less frequently. If the boat corrects its heading every 5-10 seconds on average, it can function for over an year or two.

      The motor will be controlled by a separate Arduino-like PCB connected to the encoder:

      Source code:

      Hatch Testing

      The hatch can be opened in order to access the electronics and it has to be perfectly watertight. The hatch in the picture is from a yacht shop and has been mounted on acrylic “aquarium” for testing. It was left underwater for 7 days and there was not a single drop of water inside the aquarium.

      To compensate the air pressure inside the hull (remember that the air expands during hot days and contracts when it cools down at night), a Gore membrane vent has been fitted on the hatch. The Gore vent is a little magic that allows air to pass through the membrane, but it doesn't let any water in. Again, it has been tested underwater for a week.

  • Boat Controller

    Andy Osusky06/07/2017 at 13:37 0 comments

    The new boat controller consists of two PCBs – the Navigator mounted on top of the Expansion Board.

    The Navigator will be responsible for the most important tasks like navigation, collision avoidance and sending messages. The Expansion Board that will provide additional functions more specific to the boat. This modular design allows to make quick modifications on the Expansion Board while keeping the more complex Navigation Board unchanged.

    Here are all features of the boat controller:

    • The microcontroller is Atmega2560 running at 16 MHz. It has been chosen because it's widely used in development boards like Arduino Mega and there's a vast amount of available libraries for various sensors.
    • It can be programmed over Wifi. This will make life easier as there is no need to open the hatch and connect the cable for programming. The boat can be tested in the ocean while staying connected to a laptop located on the shore or motorboat. With a long range Wifi antenna, the program can be uploaded even hundreds of meters over the air.
    • Tilt compensated compass. There will be also an auxiliary compass that will be mounted far enough from magnetic noise.
    • Accelerometer & gyro. The motion sensor will give us a better idea about what the boat is actually doing, especially during storms and high winds. It will report pitch & roll, average wave height, etc.
    • Battery power sensor.
    • 2 MB flash memory for data logging.
    • Experimental 256 KB FRAM memory which is faster than flash.
    • Temperature, pressure and humidity sensor. It may discover potential problems inside the waterproof housing such as leaking, overheating or need for pressure compensation.
    • Watchdog timer based on a low-power microcontroller that monitors the “heartbeat” of the main CPU. If the Navigator doesn't respond for a minute or it reports any kind of failure, the watchdog will cut power for a few seconds. This is how we usually fix problems. :)
    • A couple of MOSFET switches to turn on particular hardware only when needed: Linux computer with a camera, satellite modem, AIS receiver (for collision avoidance), RC receiver and water pumps. Wondering what the water pumps are for? They will pump water out of the boat if flood sensors detect big trouble...

    Power Sensor

    There will be one additional board that will measure voltage and current of each solar panel separately. It will be interesting to see which panel is shaded by the sail at any particular time.

    Complete hardware scheme:

    The source is published on GitHub:

  • New Design

    Andy Osusky11/22/2016 at 10:05 0 comments

    Below is the design of the new autonomous boat that will attempt to cross the Atlantic. It will be built from carbon fiber, fiberglass and Kevlar. The total length will be 2.2 metres (7.2 feet). The long and narrow hull is optimized for speed. Instead of a typical sail, there is a rigid wingsail as seen on modern yachts.

    First, I am going to build a miniaturized version to test the hardware and software. I will keep you updated on the progress!

  • Additional Trackers and Hacking SPOT Trace

    Andy Osusky11/03/2016 at 10:01 0 comments

    As explained in the project details, there are three trackers on the boat. The RockBlock module which is connected to the Arduino-based controller is transmitting interesting data via the Iridium Short Burst Data service; such as the GPS position, the battery voltage, power consumption, temperature, wind speed, etc.

    In case the main hardware fails, there is another tracker called SPOT Trace that is transmitting only the current position via the Globalstar satellite network. It has an independent power source made of four NiMH AA batteries being recharged by two 6V / 50mA solar panels.

    Because SPOT Trace may permanently turn off in case it loses power (for example, when the batteries completely discharge or when the connection breaks for a moment in rough ocean conditions), a timer 555 periodically sends short pulses to the SPOT Trace switch.

    You need pretty good soldering skills to connect the wires to the switch. All soldered connections that may break off were potted with epoxy. Another great hack was to solder wires for an external battery source for two reasons – a larger battery capacity would provide enough power during a series of rainy days. Secondly, I wouldn't trust the micro USB connection.

    For testing purposes, a vibration motor from a mobile phone was glued to the vibration sensor to ensure that SPOT Trace continuously reports position, even when it is not moving. It is not necessary for the ocean as the ocean waves are continuous and never stop. :)

    The day before launch, I added a third tracker which is another SPOT Trace. However, it's powered only by non-rechargeable batteries. Based on the tracker power consumption when reporting position every hour, eight D cell alkaline batteries should last about two years.

  • Navigation Software from Scratch

    Andy Osusky10/31/2016 at 12:45 0 comments

    Existing open-source solutions for drones were not suitable for this project. Below are the most important points where the boat differs from typical applications:

    1) Tilt-Compensated Compass

    A small boat is constantly bouncing up and down while riding high waves. Therefore a tilt-compensated compass LSM303D was used to find the correct heading. The compass combines a 3-axis accelerometer and 3-axis magnetometer.

    2) Spherical Coordinates

    If you fly a drone, you probably don't send it over vast distances across an entire continent. Some flight controllers do calculations by using the Pythagoras theorem, which is valid only on a flat surface. For a greater precision, we need to count in the Earth curvature which is significant for the path across the Atlantic.

    3) More Sophisticated Error Correction

    If you try to drive a small powerboat in wild ocean conditions, you will find out quite quickly that it's not as easy as driving a car. As the boat is often turned by the waves from side to side, it has to take action by adjusting the rudder, but not too often as the servo would quickly wear out. The servo has to be operational for months! A PID controller has to be implemented to keep the boat in one direction while being friendly to the servo at the same time.

    4) Magnetic Declination

    Magnetic declination, i.e. the angle between magnetic north and true north, can make a difference by as much as 20 degrees. While it is not absolutely critical for a successful mission, it's worth implementing the World Magnetic Model into the navigation software to measure the heading more precisely. The actual model is a very complex formula with plenty of experimental constants that can change over time. So, I calculated the values of declination on a sphere mesh and stored them in the Arduino flash memory.

View all 12 project logs

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