A survey by a Marine Robotics Team from University of Limerick (UL) using the UL built Smart ROV Latis has shed new light on two shipwrecks off the coast of Donegal, the S.S. Empire Heritage and the S. S. Empress of Britain.
The survey onboard the RV Celtic Explorer led by Dr. Daniel Toal, University of Limerick (UL) captured photo images as well as multi-beam sonar images at two archaeological sites. The survey planning drew on the knowledge of technical diver Dr Ger Dooley, a member of the survey team who has dived on many wrecks on the northern approaches off the Donegal Coast.
High resolution sonar imaging was used to create new images of the S.S. Empire Heritage, a cargo ship which had been carrying dozens of Sherman Tanks when it was torpedoed and sank in 1944 with the loss of 113 lives. New images of the S. S. Empress of Britain, a passenger liner, thought to have been carrying gold when it sank in 1940 were also created.
The S. S. Empire Heritage now lies at a depth of 70 metres, 15 miles north-west of Malin Head and the survey captured images of the cargo of tanks, originally destined to fight in WWII, now scattered across the seafloor.
The S. S. Empress of Britain, a 42,000 ton, 230 m passenger liner lies at 160 metres, 40 miles north-west of Bloody Foreland and is believed to be the largest ship sunk by a U-boat.
A salvage operation carried out on the wreck in 1995 on suspicion that the ship had been carrying a large cargo of Gold from Africa destined for America reported finding the Empress upside-down in 500 feet of water.
The salvagers reported breaking into the strong room only to find a single skeleton and no gold. It was suspected the gold was unloaded while the Empress was on fire and its passengers were being evacuated. However, the high resolution sonar image which was taken during the recent ROV dive shows the wreck listing on its side, not upside-down as reported by the earlier salvage operation.
The aim of the survey was to trial ROV technology developed by UL for a variety of marine applications including high resolution sonar imaging of ship wrecks for archaeological records, demonstration of ROV Latis’ precision underwater navigation and dynamic positioning capabilities to the Irish Coast Guard for Search and Rescue, as well as trialling a ‘daughter ROV’ or ‘fly-out out mini ROV’ for hull penetration and internal inspection where the larger ROV Latis cannot venture.
Dr Toal explained: “In order to acquire high resolution sonar images the sonar instruments must be flown close to the ship wreck. Building a composite sonar image of a wreck with large numbers of sonar pings requires precise knowledge of the position and orientation of the ROV platform during the imaging transect. The ROV Latis is equipped with state of the art under water positioning, navigation and auto pilot control systems which makes it an ideal platform for this high resolution survey work.”
When poor weather conditions during the six day survey prevented operation of the ROV, the team moved to the sheltered waters of Lough Swilly where they tested a new low cost terrain referenced navigation system for unmanned vehicles developed by the Marine Robotics Research Centre at UL.
The survey was supported by the Marine Institute through the 2012 Ship Time Programme as part of the Sea Change Programme funded under the National Development Plan 2007 -2013. The shipwrecks surveyed were previously mapped from the sea surface by the Geological Survey of Ireland and Marine Institute during the INSS and INFOMAR national seabed mapping programmes.
Further details and information on the shipwrecks are available in the new book published this week by government publications, entitled “Warships, U-Boats & Liners”.