Ocean wave measurements via smartphone

During wave measurements in Durban, South Africa, Radermacher and Thackeray lost contact with their conventional buoy. “Those buoys are so expensive that it is worth a helicopter trip to search for it,” Radermacher explained. “As buoys float in the open sea, it is hard to supervise them and theft and damage are all too common.” Thakeray then wondered why these buoys are overpriced, while the sensors needed can simply be found in your pocket. Using Radermacher’s knowledge on ocean wave theories and software, they together developed a buoy which is ten times cheaper than its conventional counterpart.

Years of research and development in the smartphone industry have resulted in accurate, reliable and most of all cheap sensors. While normally used to turn the screen or navigate, apparently they are suitable for wave data collection as well. By using the accelerometer and gyroscope in the smartphone, the buoy measures the height, direction and period of waves. “The data is immediately processed in the smartphone and via an internet connection, the client is provided with real-time wave data,” Radermacher explained. Extensive prototype testing resulted in almost an exact copy of the conventional buoy measurements. “The data turned out to be more accurate than we ever dreamed of,” Radermacher said.

The strength of WaveDroid lies within applications close to shore. It allows, for example, harbours to inform ship transport and coastal engineers to predict coastal erosion. Because 3G connection is necessary to provide real-time data, and battery life lasts only three months, employment at open sea is less suitable. “But this fits in perfectly,” Rademacher explained. “A lot of buoys are necessary when measuring coastal data, as waves tend to vary a lot here. WaveDroid provides a cheap alternative compared to conventional buoys.”

The first commercial pilots have already been conducted with a Dutch dredging company and WaveDroid buoys are now tested in Myanmar, France, the Netherlands and Brazil. Especially in poor countries with a lot of coastal water issues, like Myanmar, WaveDroid may offer a solution. Martijn Kwant, a student at the Faculty of Civil Engineering and Geosciences at TU Delft, collected wave data there using WaveDroid. He stresses the importance of wave measurements for flood control with the local university and government.