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Nah Yeah Buoy

A Buoy that can detect a rip and change colour depending on the danger of the rip

What it does

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.

Your inspiration

Rip currents are one of the leading causes of rescues by beach lifeguards and deaths by drowning in many countries including New Zealand where beach activities such as swimming and surfing are an essential part of everyday life. From countless conversations with lifeguards, their frustration with the lack of modern methods of identifying rips and communicating the danger to beach goers had surprised our team, and we have dedicated ourselves to developing an advanced yet intuitive solution to the serious safety issue.

How it works

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.

Design process

Our team first investigated the characteristics of rip currents. Contrary to common belief, they sometimes appear to be smooth on the surface without any breaking waves and geographical peculiarities result in vastly different appearances and types of propagation by beach or area, which led us to the conclusion that deploying a sensor network is the most effective option. Several sensing methods, including pressure, flex and fluid flow sensors, were then compared through a series of experiments and our results favoured the use of the fluid flow sensor. We then looked at form. Various types of fins in combination with materials were developed in consideration of where the sensor will be placed and how to make the circuit waterproof. Scale models and prototypes were constructed and tested in a water bath to find the optimal design, and our parts were 3D printed and assembled to complete the final form. We also created a mobile app for lifeguards which lets them adjust the thresholds and control the buoys individually or as a whole to ensure water safety. For example, all buoys may be flashing in red if there is a significant danger such as a shark, to ensure swimmers leave the water quickly, or while there are no lifeguards on duty.

How it is different

The most common method of identifying rip currents is observing the water from a high vantage point, and warning signs and flags are often placed in an attempt to alert beachgoers. The primitive methods, however, are obviously less accurate and effective: a whopping 80% of rescues are associated with swimmers caught in rip currents according to the Surf Life Saving NZ; and the US Lifesaving Association estimates more than 100 deaths each year are due to rip currents. By contrast, the “Nah, Yeah buoy” is designed to provide information of the rip currents accurately and intuitively, which can inform both swimmers and lifeguards. For swimmers, the buoys are easy to sight and prevent them from getting into a danger area as often rip currents result in swimmers being moved along the beach and out of sight of the flags. For lifeguards, the app helps them get a better view of the ocean currents and alert swimmers efficiently.

Future plans

To develop the “Nah, Yeah buoy” into a real-world solution by working with lifeguard organisations and government agencies around the world. We set three objectives: Firstly, we wanted to refine the fluid flow sensors further or test advanced sensors such as underwater wave pressure sensors which could help detect deadly rip currents more accurately. Secondly, we want it to be powered with renewable energy either wave or solar energy. Thirdly, we would also like to up-cycle ocean plastic waste for future production as our school has expertise in plastic up-cycling as evidenced by the world’s first plastic recycling 3D printer, Recyclebot.


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