Treasure hunt

A UK company using advanced technology to find and recover sunken treasure has located its first target — a 19th century shipwreck containing up to £4.5m in bullion.

SubSea Resources, which is employing a range of systems in its treasure hunt, many borrowed from the oil and gas industry, said it plans to begin its first recovery operation on the wreck Ella next month.

The wreck lies about 1,000m beneath the Atlantic, and according to the company contains a haul of gold and silver that can be extracted from the vessel. SubSea hopes to recover treasure worth an estimated £100m from six wrecks by mid-2008.

The planned recovery from Ella will be a testing ground for much of the technology and systems that SubSea plans to use for bigger, more profitable wrecks next year.

The team uses sonar technology from the oil and gas industry to map the seabed. Once it knows roughly where a wreck should be, it maps out a search zone.

A side-scan sonar is then used to determine the exact position of the wreck within that zone. The torpedo-shaped sonar is pulled behind the survey vessel to ‘sweep’ the seabed, covering each area twice to provide an overlapping image. Around six to eight miles a day can be covered, working 24 hours a day.

The exact location of the wreck is then pinpointed using GPS.

Once the wreck has been located, the survey vessel uses dynamic positioning technology to keep itself in exactly the same position. This is a sophisticated computer system that manages the ship’s engines and side thrusters coupled with GPS data to compensate for current, swell and wind.

SubSea can use ROVs for some light recovery work, main picture, from wrecks such as Celia, inset pictures, on which it plans to begin work next summer.

To complete the survey, a remotely-operated vehicle (ROV) fitted with short-range sonar, video equipment and a stills camera confirms the identity of the wreck.

SubSea managing director Mark Gleave admitted that the most recent survey had been far from plain sailing. ‘After three hurricanes, two engine failures, sonar failure and an ROV failure, we have managed to complete the Ella survey,’ he said. ‘But it is all part of the learning curve.’

The project then moves to the recovery phase, which according to Gleave is when the technical challenges will really begin. ‘We can use an ROV for some light recovery work, but it can’t carry more than 100kg,’ he said.

Gleave was keeping the finer details of the recovery operation close to his chest — Sub- Sea is not the only company searching for profitable wrecks — but did reveal the basic principle behind it.

‘When recovering heavy cargoes we use a grab system to unload on to the seabed and then we recover it piecemeal from there,’ said Gleave.

Large skips are positioned next to the wreck, and the grab deposits the cargo into them. Above the grab, there is a control pod containing hydraulics, sonar, lights and equipment to measure how much the grab is carrying. While SubSea will begin with Ella, its real targets lie elsewhere.

While attempting Ella’s recovery it will also be undertaking the survey of a nearby wreck, Miranda, that contains around £22m worth of nickel. Next summer it will turn its attention to Celia, containing 5.5 thousand tonnes of copper, valued at around £11.5m, which was surveyed earlier this year.

Before undertaking the survey phase of the operation SubSea buys the wreck from its owners — in Miranda’s case the US government.

Although the current wrecks are relatively accessible, Gleave hopes the company will go deeper in its treasure hunts in the future. ‘We should be able to get to 6,000m deep in the next 10–20 years,’ he said. ‘The equipment is all rated at that depth, but for the time being we have got plenty to be getting on with in shallower waters.’