Underwater harvester supports seagrass revival

New technology is being developed to speed up the restoration of threatened seagrass meadows.

Engineering firm Tandem Ventures has partnered with conservation charity Project Seagrass to design and test an automated underwater harvester capable of cutting and collecting seagrass seed pods – work typically carried out manually by divers. 

Using Onshape, a cloud-native CAD and product data platform, the team collaboratively designed a prototype featuring a datalogging “brain” to monitor depth, pressure, turbidity and temperature.

The prototype was tested in Porthdinllaen Bay in Wales, one of the UK’s most important remaining seagrass habitats. 

A limited trial run successfully collected seed pods using a new pump-filter system designed to minimise environmental disturbance. 

Onshape’s real-time editing and version control helped the design team iterate quickly between test sessions.

Custom components such as hinges, joints and protective guards were produced with Bambu Lab’s H2D 3D printer, while the craft, which was roughly the size of a small car, was built with marine-grade stainless steel fasteners from Accu Components to withstand harsh underwater conditions. 

Electronics supplied by Mouser supported the core sensor system.

Following the North Wales experiment, Tandem Ventures is currently working on an entirely new pumping system to increase reliability and simplicity as the project moves into its next phase.

Sam Rogers, co-founder of Tandem Ventures, said: “The aim is to make harvesting seagrass seeds 100x faster than the current methods, in which scuba divers collect them one-by-one manually.

“Tests were promising with a radically increased collection rate, and this has given us the confidence to go away and look at refining the prototype, including upgrading the pump.

“With seagrass restoration initiatives in operation worldwide, the team at Tandem hope the implications and learnings from these trials will have a global impact.”

David Katzman, general manager of Onshape and Arena at PTC, added: “The seagrass harvest project is a perfect showcase for how our software can help innovative organisations achieve success in demanding environments.

“All of the features we’ve packed into Onshape are included to make design changes faster and in real time, with collaboration anywhere in the world one of the unique offers that accelerates iterations and gets products to market quicker.

“After the initial trial, a flexible 3D printed blade guard, heavy duty crank-handle adjustable legs and a host of robustness upgrades were also added to the craft.”

David added: “We’ll continue to work with Tandem Ventures and Project Seagrass to further improve the prototype and, hopefully, create a faster more efficient solution to keeping seagrass meadows alive in the future.”

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