Safety-promoting mobile application

Using iOS & Android devices and BLE beacons for person location and incident alerts

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Problem to solve

The application addresses the problem of safety for individuals and groups while on the open water, in the mountains, woods, caves, or other environments where getting lost is highly probable and may prove fatal.

For example, people, children, and pets on motor and sailing vessels quite often fall overboard. If it happens unnoticed by others, the crew eventually may have difficulty locating the spot, whereas they might have minutes to recover the person, e.g., when the water is cold.

A prompt alarm and clear direction to the incident spot are essential for overnight passages, couples, and families.

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Onix’s client envisioned a person/object location and alert system. It incorporates wearable water-proof beacons working as location alert transmitters, individuals’ mobile devices, and optionally, a full-function control device suitable for bigger vessels. A designated mobile application turns everyone’s smartphone or tablet into a person-tracking and alarm system.

Plus 2

Each individual in a group, e.g., crew and guests on board, including children and pets, would get a wristband or tag that can be securely attached to their body and assigned their name. Through the app, the safety system would integrate their personal smartphone or tablet and link it to one or several wearables. Tags may be attached to objects as well.

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The system would be constantly tracking all beacons around the vessel. If one of the beacon wearers moves away from the control device or main mobile device in the group, such as the captain’s or guide’s, the system would detect it and automatically alarm the rest of the group through their mobile devices. Having recorded the missing person’s last coordinates, the system would direct the crew back to the point of loss, promoting rapid recovery.

The wearables are also equipped with a water-activated strobe light that increases the lost person’s visibility at night.


Killer feature

Through the app, a virtual tether is formed between each beacon and mobile device in the system. Multiple beacons can be connected to a single mobile device, and vice versa, one beacon can be connected to multiple phones, tablets, and in the case of Apple devices, also iPod Touch and Mac.

The mobile app technology can detect a break in the virtual tether, e.g., when a person or pet falls overboard, within 8 seconds; no cell phone signal is required.

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This would trigger the system that will automatically:

  • I.

    record the time and latitude and longitude where the person was last detected using their mobile device’s GPS;

  • II.

    make all connected mobile devices flash and sound a loud alarm, notifying the rest of the group of the incident and who exactly needs to be rescued.

The system will display the main group’s current GPS location and the missing person’s last known GPS position, and will show the direction, in a compass format, back to the point of loss.

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Additional features


The safety system is scalable. It can have:

  • A main mobile device tracking the signal directly from up to six beacons (this is sufficient for vessels up to 40ft)

  • A 5V USB hub tracking up to 15 beacons (suitable for vessels up to 50ft);

  • A 12V wired hub tracking up to 15 beacons and acting as an engine kill switch in case of an incident.

When the mobile app is connected to the hubs, it allows greater control over the beacons that are being tracked.

Safe storage

The system stores the time of an incident and all location data required by the rescue services.

If a prompt recovery is not possible, the system automatically inputs the coordinates into a VHF MOB (man overboard) script to aid in transferring concise information to the emergency services.


For those sailing, hiking, or traveling solo, the app’s eponymous mode promotes safety as well.

The person enters an emergency contact in the app and places their mobile device securely somewhere on the boat. In MOB situations, it will automatically send an SMS with incident GPS coordinates to the emergency contact’s mobile phone.

The system thus helps:

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    Ensure all crew, guests, family members, children, and pets are safely onboard

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    Increase the chance of prompt rescue in a MOB incident

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    Quickly transfer information about MOB to coast guard and emergency services


The client approached Onix with the MOB location system concept and the task of writing a stand-alone mobile application to operate brand hardware: wristbands and float-on tags with Bluetooth Low Energy (BLE) beacons, and control hubs. Onix’s as a travel software development company implemented the entire application logic.

The client also provided the visual design for the first phase of the project - the development of a system incorporating only BLE beacons.

The second phase included external hardware and a list of commands.


Technical challenges and technology stack

The iOS version of the application was coded in Swift.

The Android app was written in Kotlin.

The project included simultaneous work with both BLE beacons using Core Location and external devices (hardware) through commands via Core Bluetooth.


The most challenging parts were:

  • the proper work with external hardware

  • development of an asynchronous data update model

  • bitwise encryption of binary data

Particularly, the sports app developers worked on an asynchronous method of polling devices. The method features subscriptions to events, such as the appearance of a new device, its disappearance, or changing parameters.

Result and prospects

The application has been released on Apple’s App Store and Google Play. The apps are compatible with iOS 11.0 and up and Android 5.1 and up, respectively.

  • ios
  • android

Currently, the free apps and the affordable portable systems that can be taken from vessel to vessel are primarily marketed to cruising sailors and boaters. However, the product has the potential for wider adoption, e.g., for organizers of guided tours, mountain hikes, extreme marathons, or other leisure and sports outdoor activities where there is a high risk of individuals getting lost and being exposed to extreme conditions. It may be useful even during routine travel, helping prevent theft at an airport, if tags are attached to luggage.

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