Custom monitoring of kelp

Dynamic Load Monitoring (UK) Ltd (DLM) has sent six DL-3.0 subsea data loggers mounted onto three cabled subsea Shackle load cells to Namibia for use in the management of a large-scale kelp forest.

“We were really interested when the quote came in for this job as it was our first R&D project for the aquaculture industry, specifically a Kelp farm,” said Chris Scrutton, technical manager at DLM.

”We were able to use our standard subsea equipment with modification to fit the structural monitoring brief. Kelp Blue needed specialised equipment in order to prove the tension load on the mooring lines of their floating structure, therefore, we custom built data loggers to monitor the load.”

Custom built

Kelp Blue, which manages the kelp forest off the coast of Namibia and originally came to DLM, with a proposition to construct equipment for structural monitoring purposes.

In the initial design stages, Kelp Blue requested subsea load monitoring devices to monitor the load tension on mooring lines on a floating structure which is tethered to the sea bed.

The subsea shackle load cell is used on applications such as subsea moorings, subsea vehicle tension monitoring and anchoring tension monitoring. It’s a proprietary data logger designed for use on applications such as array cable monitoring, monitoring of subsea acceleration and measurement on offshore structures, including wind turbines.

The DL-3.0 is used for long or short term deployments on offshore and subsea structures. A key feature of this data logger is its ability to monitor the weather conditions, specifically the acceleration of waves, which is helpful for matching computer modelling scenarios against real world conditions.

Some of the challenges that came with the project were the requirement for the data logger to be simple enough for divers to collect the data on a short dive time. Therefore, DLM designed the data logger with the application in mind, specifically using wing nuts, making sure they were easy to undo in a short amount of time and more accessible to take off if the diver had gloves on.

During the design stage, the packaging of the data logger and mounting it onto the subsea shackles was challenging, so DLM’s design engineers overcame this problem by specific designs of the subsea pod and 3D printing internal parts of the housing, making sure it was secure.

Past projects for DLM have included the monitoring of array cables for offshore windfarms and in future, it will be involved with projects including solar array.