There are a number of reasons the Port of Leixoes, Portugal needs to keep on top of its bathymetry, including – but not limited to - sediment transport. However, while it used to be a matter of loading up a vessel with survey equipment, these familiar methods are on the cusp of change.
“We are already at the tipping point, where a day’s surveying with an AUV is about the same price as hiring a boat with three men” Michael Boniface, research lead at the UK’s IT Innovation Centre told MJ.
He believes the future, is smaller, lighter, more adaptable – and both cheaper and safer. Importantly, Leixoes – a testbed of the EU SUNRISE project and IT Innovation Centre partner - is not just putting a single prototype AUV into the water but is showing that it’s possible to combine survey information with many other inputs to allow rapid assessment of hazard and risk.
At the heart of it lies flexibility, while some information may be from AUVs, others come from harbour craft, sensors on stationary assets or even satellite images. There have been issues to overcome: radio waves attenuate very rapidly underwater so the solution has been an acoustic link to a wifi hub on the surface, but the end result is an accurate picture of the marine environment.
Interestingly, Leixoes has already found its high-tech solution useful. Paulo Dias of LSTS, another of the project’s partners, explained that a container blew from the quay during a storm: this created potential issues for safe navigation as the access channel is narrow and extremely busy. First of all the port staff went out with a grapple and line to try to snag it but with bad, post-storm water visibility they were fishing blind.
So, one of its new AUVs was sent out to run on a pre-programmed course through the port’s waters: this succeeded in locating the troublesome box in around half an hour.
Certainly ports could lighten their maintenance burden if dredging programmes are not just scheduled but made responsive to need: it would minimise expensive dive surveys as these AUVs can build up a picture of the bathymetry and put it all together with current velocity, salinity, temperature, pollution, oxygen levels and anything else of interest. And an AUV is deployable by a single man.
However, the emerging technology is also going to be useful for the offshore renewable and oil & gas industries in investigating dramatic scour events impacting everything from HVAC cables to pipelines and wind tower foundations. These, says Mr Boniface, could be owned by the wind farm operators or provide an interesting revenue stream for contractors: Marine South East, another project partner, is actively exploring a range of potential commercialisation opportunities for these AUV capabilities.
It will raise safety levels and asset lifecycle: conditions too extreme for a manned vessel are often the moments an operator would most like to check what’s happening below the surface. In fact it’s not unknown for a series of storm events to preclude a detailed investigation of subsea structures for months.
As Mr Dias explained that there is huge value in “being able to provide a rapid environmental picture” and an AUV – or number of AUVs working in swarm formation – could help everyone rest easier.
By Stevie Knight
