Peeter Ude: We found the source of the mysterious signal

Underwater beacon next to the wreck of MS Estonia. Photo: Kuvatõmmis videost

Hydrographer Peeter Ude, working as part of the private MS Estonia expedition, has not yet found the shipping containers he believes lie next to the wreck of MS Estonia. However, an autonomous underwater vehicle (AUV) piloted by Ude happened upon three peculiar metal constructions topped by what appear to be lighthouse-like columns.

The objects lie roughly 100 meters due north of the wreck and have clearly been put there by people, which is precisely what expedition lead Margus Kurm has hoped to find to understand whether they might be connected to the disaster.

“I do not know what they are, ask Peeter Ude,” Kurm told Postimees. Hydrographer Ude said the objects are underwater beacons that were likely submerged when efforts were made to cover the wreck in concrete to protect the victims’ resting place. The plan was abandoned due to strong opposition from next of kin.

Used to facilitate navigation

Ude said such devices make it easier for AUVs to navigate the area. The beacons are used for precision work, sending out signals from fixed geometric positions to facilitate navigation. “They are simply devices that make it easier for AUVs to navigate,” he said.

The hydrographer added that the beacons were likely put there to monitor work to survey the MS Estonia wreck. “Because the hull is on a hillside and occasionally slides down, someone has likely installed the beacons to make it easier to survey it.”

Such devices are not cheap, which raises the question of why would someone leave them on the seafloor. “They have been left in place to fix the position of the hull and avoid potential mistakes installing new ones,” Ude, who also took part in the Estonian Safety Investigation Bureau’s expedition this summer, said. Work to study the hull and the surrounding area using sonar was disrupted by a mysterious signal then.

Ude believes he has found the source of that signal now. “Looking at the direction of the noise, there is a 90 percent chance the beacons were operational when we were trying to get our images,” he suggested, adding that he believes such beacons can be activated and deactivated from a distance.

Alternating signals

Asked where the devices that were taken to the MS Estonia disaster site decades ago might be getting their energy, Ude said it is the most mysterious aspect. “I cannot tell you what triggered them and caused them to interfere with our work the last time,” he said. The hydrographer believes the devices could have been the source of the disturbance as the noise he saw on his screens in summer was changeable. “The very idea of these devices is to send out alternating signals that makes it possible to triangulate the AUVs position,” Ude said.

Diver Kaido Peremees, who also accompanied the state’s official expedition, agreed in that the devices could be submerged beacons. “It is an aging system, with newer and lighter alternatives used these days. It can be guessed – and I would stress that this is just a guess – that the beacon fell silent because its battery went dead in the cold and efforts were not made to recover it,” Peremees offered.

Work on board the RS Sentinel continued on Wednesday. Because visibility is poor 70-80 meters below, the crew once again tried to survey damage to the starboard side of the hull. Next, objects around the wreck, discovered using the RS sentinel’s multibeam sonar, were studied. The latter include various bits of the ferry, life raft covers, moorings, boxes and various other objects.