HMS Magpie helps safeguard crucial commercial port during Thames operation

HMS Magpie hoovered up vast amounts of data – in particular in waters around London Gateway, the second most important container port in the UK.

The survey work carried out by Magpie will provide a detailed picture of the Thames riverbed and any changes to it – natural or potential interference by unknown actors – to help with the safe passage of shipping in the estuary, support security of underwater infrastructure, and also lay the foundations for possible exploitation of these same waters.

Opened just over a dozen years ago on the left bank of the Thames near Canvey Island, it’s now eclipsed Southampton to become the second largest container port in the land behind Felixstowe, handling a record 3 million containers last year.

Around one third of all the UK’s containerised imports and exports flow through this port.

“By providing this picture of the maritime environment Magpie has built the foundations necessary to ensure the River Thames and the strategic ports therein, are able to remain safe and open to all users of this critical waterway in time of conflict,” said Lieutenant Daisy Nelson, Magpie’s Commanding Officer.

“It is this enduring work that Magpie conducts – alongside her sister vessels in the Royal Navy’s Hydrographic Exploitation Group – which assure both freedom of navigation and understanding of the underwater battlespace, now and into the future.

“We cannot be sure what the operational commanders of tomorrow will need, but we can be sure that as far keeping our critical national waterways open goes, we’re ready.”

Operated by a handful of specialist Royal Navy hydrographers, Magpie’s primary role is to produce highly accurate bathymetric (water) data to support military operations in inshore waters.

Despite her size – just 18 metres long and displacing a mere 37 tonnes – the Devonport-based craft is packed with the very latest survey equipment which can gather astonishing amounts of info.

Her multibeam echo sounder can send out more than 500 individual pulses of sound into the water column at once, 400 times a second.

The area covered by a ‘ping’ depends on the depth of water; those within the Thames allowed up to 65m of data to be collected in a single ping.

And given the high frequency and resolution of those sonar systems, Magpie can move at higher speeds than traditional inshore survey vessels – which means she can cover up to 270 square metres of the seabed per second… or an area the size of the Wembley pitch every 30 seconds.

Over the past three months she has detailed the depth, topography and seabed type of the Thames with accuracy down to a centimetre.

This data is now being pored over by experts at the UK Hydrographic Office in Taunton, who produce the highly-accurate charts used by both the military and civilians to safely navigate the world’s seas.

The ship was also tasked with surveying the waters around the Royal Navy’s home on the Thames, HMS President, at St Katherine Dock near Tower Bridge.

The reservist base, which frequently hosts maritime visitors from across the service, is subject to a punishing tidal regime.

Spring tides sees up to up to 30 million tonnes of water racing past the jetties in a single tidal cycle – which has a marked impact on the topography of the surrounding riverbed.

In a matter of hours, the Magpie team provided an accurate three-dimensional image of the area surrounding HMS President’s underwater infrastructure, which will be used to ensure the long term sustainability of the Royal Navy’s ‘base’ in London.

During data collection, the ship hosted her affiliated livery company, the Worshipful Company of Tylers and Bricklayers, along with a group of MOD civil servants.

The expert crew showcased the wider application of the ship’s survey outfit – including a single beam echo sounder, which can reach into the seafloor substrate itself – and a side scan sonar that produces detailed photogrammetry of seabed features and objects.