A new Australian innovation could allow cheaper seafloor testing for offshore wind farms.

Australian engineers have developed an innovative device, inspired by a modified speargun, to test seabed soil efficiently and cost-effectively for offshore wind farm projects. 

This device, created by researchers at RMIT University, propels a probe into the seafloor to gather critical data about the seabed.

Traditionally, seabed testing involves winching or dropping probes, known as penetrometers, from support vessels. This method is expensive and less effective in shallow waters with sandy seabeds. 

Heavy-duty probes, which can penetrate these seabeds, cost up to AU$200,000 per day. Lighter probes, while less costly, often fail to penetrate the dense sand effectively.

The RMIT researchers tested their device using various probe tips and sand mixes in a water tank. 

Equipped with sensors and high-speed cameras, the experiments showed the new device's impressive performance. 

Published in the Canadian Geotechnical Journal, the results indicate that the device can penetrate the seafloor twice as effectively as existing lightweight testers, and is far more cost-efficient than heavy-duty probes.

Junlin Rong, the study's lead author and an RMIT PhD candidate, has emphasised the significance of the findings. 

“In laboratory environments, the device showed considerably greater penetration potential compared to free-falling probes on soil. Notably, in high-density sandy material, the penetration depth was twice that of previously reported values achieved by freely falling probes,” Rong stated.

Rong believes this breakthrough technique could transform site investigations for wind farm projects. 

“This breakthrough technique has the potential to revolutionise site investigations for wind farm projects, offering significant time and cost savings while outperforming the embedment achieved by other dynamic penetrometers.”

Designed with environmental concerns in mind, the device allows for probes to be retrieved and reused after data collection, minimising seabed disturbance. 

It can also be adapted to existing probes, enabling engineers to upgrade their current equipment with minimal investment.

While existing cone penetration testing methods remain essential, Rong noted that their launching system could reduce the number of these costly tests needed, leading to substantial savings.

RMIT Professor of Geotechnical Engineering Majid Nazem announced the next step for the project: field trials. 

“Now that our experiments have demonstrated the device’s ability to achieve considerable embedment depth in dense sand, we are keen to conduct field trials and collaborate with our potential industrial partners to further test its performance for offshore geotechnical engineering applications,” Nazem said.