Drowning is the third leading cause of accidental death in New Zealand, and the vast majority of lifeguard rescues are due to rip currents—hard to observe unless you’re already in peril. In order to help fix this problem, Victoria University of Wellington students Hannah Tilsley and Chamonix Stuart designed the “Nah Yeah Buoy” water safety system.

The system consists of a network of sensing buoys and a mobile app. The buoys feature a water flow sensor on their base to measure currents, and use an Arduino to control lights on the top to shine according to the water speed. Green means it’s safe to swim, yellow is for caution, and red indicates danger, in similar manner to how traffic lights. Additionally, two-way wireless communication sends alerts to lifeguards on the shore, who can override the lights to warn of danger when needed. 

As seen here, the project was named a runner-up in the 2019 New Zealand James Dyson Award.

The “Nah Yeah Buoy” is an adaptive system for water safety designed to identify rip currents near beaches, visualise their locations and movements, and provide interactive alerts and warnings for lifeguards and water users.

Our “Nah Yeah buoy” consists of a network of sensing buoys and a mobile app for lifeguards. Rip currents are characterised by a localised strong flow of water that moves away from the shore at a typical speed of 0.5 to 2.5 meters per second. Each buoy of the network has a customised fluid flow sensor at its bottom to measure the strength/speed of the water as it flows through, and the value is compared to a set of thresholds by a built-in microcontroller real time. A high-intensity light placed on top then indicates the level of danger in three colours: green for “Yeah” (good to swim); orange for an alert; and red for “Nah” (do not swim). The buoys also transmit the information wirelessly to an app on the lifeguards’ mobile devices which allows them to adjust the thresholds as needed. The buoys are lightweight, very easy to install and individually manageable and form a network automatically.