OWL's Watch

The perfect companion for single-handed sailors in need of an extra pair of eyes.

Feeling secure when at acnhor is key to make the sailing experience plasanter. With the devlopment of this system, it will be possible to monitor at every time the position of the boat relative to the anchor . Thanks to the implementation of IoT (Internet of things), and data processing, the crew will always be updated with boat information coming from sensors at a glance. The system makes use of a GPS module connected via wifi signal to the boat main processor, from which the data comes out into a LCD screen.

The module is attached to a self-deployable anchor buoy which is provided with all the electronics needed including batteries. The wifi antenna range is close to 1 km, so the transmission will be perfect taking into account that the distance between boat and anchor seldom surpasses 50 meters.

OWL's Watch

The aim of this project is to develop a system capable of making the anchoring safer, by monitoring the location of the boat relative to the anchor. When the anchor starts to drag, the crew member will know within seconds, having then enough time to act.

After this brief summary, let's talk about the reasons why we developed this project.

It is well known that anchoring has its risks, specially when spending the night. That constant dreamy thought of the boat to be dragging directly into the rocks blown by the wind is something we wanted to avoid . Anyway, I personally would rather sleep that being all night long cheking the anchoring!

Having all of this in mind, we decided to find a solution by our own.

The idea

We had to think of a system capable of tracking the location, storing and processing the received data, and sending it back to the boat. Then, there should be some kind of display to check the info coming from the GPS, and, of course, an alarm system to warn the crew in case of risk of anchor dragging.

At first we thought of installing the GPS beacon on the bow. It is easier to mount, to check, to maintain and do repairing.... but, as the boat describes circles around the anchor depending on the direction of the wind, that was not the best option. (It would work indeed, but not as precisely as we needed)

So, we needed something that stood just over the anchor. Here is when the anchor buoy comes in.
Using the anchor buoy, we found the perfect solution for our experiment, hence it is always just over the anchor at every time (taking into account that it also describes a circle around the anchor but quite small).

Deploying the anchor buoy

As we wanted to create an automatic system, the idea of having to deploy the buoy manually at every time we anchor didn't fit in our plan. We finally decided to use a self adjusting anchor buoy system. With this mehcanism (shown below) it is not needed to measure the lenght of the rope every time. This also means that the GPS located inside the buoy will be always in the optimal position relaitive to the anchor, justo above it. It is crucial for the GPS to lay upon the anchor, since it will determine the accuracy of the system. If it was floating far away from the vertical line from the anchor, there will be an extra error in the calculation of around 5-10 meters. If we consider this possible error plus the GPS error (+-5meters) this results of an error of +-15 meters. Hence, limitating the error due to GPS positioning is key.

Sending the signal and reading the data

At first we thought of installing the GPS beacon on the bow. It is easier to mount, to check, to maintain and do repairing.... but, as the boat describe circles around the anchor depending on the direction of the wind, that was not the best option. (It would work indeed, but not as precisely as we needed)

So, we needed something that stood just over the anchor. Then is when the anchor buoy comes in.
Using the anchor buoy, we found the perfect solution for our experiment, hence it is always just over the anchor at every time (taking into account that it also describes a circle around the anchor but quite small).

Sun powered electronics

The electronics inside the anchor buoy receive its energy from a 10w solar panel located on the top of the buoy. It has been designed with an specal shape that allows the solar system to be installed. The panel is connected to a small lithium battery (xxxah). In order to minimize the energy consuption the wifi antenna only emits data every 60 seconds.

Now, let's get technical...

The main components of the whole system are listed below:

Controller Board Arduino Mega 2560.
Controller Board Arduino Uno R3
Wifi Module Antenna NRF24l01 (x2)
LCD Screen
6V-100mA solar panel
GPS Module Ublox NEO6M V2
Anchor buoy with self adjusting system
DC Power Supply
Micro SD Reader Module
18650 lithium batteries (x2)
TP4056 Li-Ion Battery Charging Module
Boost Converter 1V-5V Input to 5V Output Step-up Converter
1N4007 PN Junction Diode
Battery case
Wires and resistors
Components casing
Speakers

The system consists on 2 separated elements, the emitter and the receiver. The emitter is located in the anchor buoy, and the receiver is in the boat. To address these two components for now on, I will call them E (emitter) and R (receiver).

E

Data from GPS

R

In the image below, both the E and R are shown. On the left, the emitter, consisting of the Arduino Uno controller board, GPS module, wifi module and antenna. On the right, Arduino Mega Controller, LCD screen, screen module, wifi module with antenna and SD reader.

The first step, was to try the GPS module out and receive the first signal. After several tries in which the moudle refused to give us signs of life, we received the first bunch of data coming from the satellites.

As shown in the images below, when the location is not fixed yet, the monitor on Arduino software displays illegible information. After a few seconds it starts to display the coordinates within the NMEA protocol. NMEA stands for National Marine Electronics Association and is currently the most common communication protocol.

Serial Monitor display a few seconds after GPS first connection,

Serial Monitor display showing data when location is fixed.

The next step was about sending the data coming from the GPS module to the LCD screen. Since we had some issues with the back light of the screen, we connected it to a DC power supply in order to provide the screen back light led with direct voltage input.

Testing wifi modules and antennas

This stage was pure coding. We needed the code to convert the incoming data to a variable that could be sent trough the antenna. Hence, as it's shown in the code below, we created a vector which included both, latitude and longitud variables. To extract the values of longitude and latitude from raw data coming from the GPS, the made use of the library TinyGPS, that we modified due to obtain the desired results.

Now, having the data packed in one vector, the receiver could start making the calculations to determine the position of the boat relative to the anchor.

Powering the board

Now that everything is set up, we decided which was the best way of keeping the emitter board (the one that is inside the buoy) working all the time without interruption. After considering several option, we went for the 18650 batteries - solar panel combination.

The component list (for the emmiter):

6V-100mA solar panel
18650 lithium batteries (x2)
TP4056 Li-Ion Battery Charging Module
Boost Converter 1V-5V Input to 5V Output Step-up Converter
1N4007 PN Junction Diode
Battery case

The board needs 5V to operate. Since the batteries were 3,7 V each, we connected them in parallel, achivieng so 3,7 V and a greater current. To increase the voltage to 5 V we used a boost converter module which delivers a stable 5 V tension, so it is possible to connect it directly to the board.

To maintain the batteries charge level, the system counts with a small solar panel placed on the top of the buoy. It will provide enough energy to charge the batteries within 6-8 full sun hours which worked perfect for us. In addition, to ensure a good charging of the batteries, it is required to install a charging module between the panel and the battery pack to avoid over charging and reverted currents (which is also solved by using a PN diode).

Now, we are going to show some calcuations regarding the estimated battery duration.

First of all: how much energy does our system draw?

Well, to obtain that value, we simply add up the currents drawn by the different components connected to the arduino board.

- Arduino UNO: 46 mA

- Wifi Module Antenna NRF24l01: 115 mA (peak while transmitting) / 15 mA (stand by)

- GPS Module Ublox NEO6M: 45 mA

Total consumption (stand by): 106mA

Total consumption (peak); 206 mA

Considering that our batteries are 1800 mAh each, connecting them in parallel will result in an output current of 3600 mAh / 3,7 V. Now, connecting the batteries output to the "Boost Converter 1V-5V Input to 5V Output Step-up Converter" we get the desired 5V output.

Making a simple calculation:

Battery capacity / Total consumption = Running hours ----> 3600 mAh / 106 mA = 33,96 hours

This will be the lasting time in the case of no power input at all. But, even in cloudy days, the solar panel will produce energy, probably not enough to charge the batteries, but to maitain the charge level stable.

Risky environment for electronics unprotected!

It is well known that floating on water is far from being the safest plece to have your electronics.

Luckily, we can rely on the protection of the anchor buoy, for the electronics are placed inside. In the beginning, the buoy was un-openable, but we attached a threaded cap to it, so it was possible to pass the electronics through it.

Now that the components are in place, the next step was to mount the solar panel. To do that, we designed a small structure that will support the panel. I has been printed in ABS, which is weather resistant and also UV resistant.

Deploy the buoy!

For we wanted the whole system to be automatic, (or at least close to that), the anchor buoy should be deployed with relative easyness and quickness. Hence, we decided to use a well known system that ensures that the buoy is as vertical as it could be over the anchor, and self-adjust the lenght of the rope that connects the anchor to the buoy, making the deploymenyt proccess so easy.

To assemble the mentioned system we used a pulley, a rope and a weight.

The schematic drawing below shows how it works.

Onboard receiver

Now that the emmiter is ready ando working, and we have a functional method to deploy de anchor buoy, it's time to move to the receiver system. The receiver will be in charge of obtaining the data coming from the buoy, operating it due to produce readable information, and finally, displaying the data on a screen and activating the alarm in case of danger.

Though the main components reamain the same, some are different as it is shown in the list below:

Controller Board Arduino Mega 2560.
Wifi Module Antenna NRF24l01
Module LCD (Connectivity IC2)
Micro SD Reader Module
LCD Screen
Components casing
Speakers

*Since on the boat we had possesses plenty of energy to use, I'm not going to show the consumption of the different componentes in this chapter.

For we wanted the receiver to be user-friendly, we designed a casing so we could fit the LCD and some buttons properly, facilitating the task of fixing the anchor final GPS position and reading of the information displayed. It also allowed us to incorporate the system within the boat desing.

To do that we used SolidWorks, which is a pretty handy CAD software. The final design of the casing is shown below.