Seabed surveys - July 2021
In July 2021, the seabed and MV Estonia's position on the bottom were examined by the accident investigation authorities in collaboration with, among others, Stockholm university.
On July 8-16, 2021, the accident investigation authorities in Estonia and Sweden performed a survey of the seabed conditions and the vessel’s position on the bottom. To a large extent, the surveys were carried out by Stockholm university. In addition, the accident investigation authorities cooperated i.a. with the Geological Survey of Sweden, the Swedish Geotechnical Institute and Tallinn University of Technology (TalTech).
The work primarily included surveys of the seabed and the vessel with various forms of sonar instruments. Some photographic documentation with ROV (underwater robot) was also carried out.
Among the measures that were taken the following can be mentioned:
Multibeam sonar with equipment mounted on ships passing over the area.
Sidescan sonar with equipment towed by a ship through the water.
Scanning sonar (Mesotech) with equipment that is lowered and placed around the wreck.
The surveys were carried out by the Estonian multipurpose vessel EVA 316 and the Swedish research vessel ELECTRA af ASKÖ.
The data collected during the survey was extensive. Immediately after the survey, the following was established.
Along the ship's starboard side there is an indentation that is roughly 20 meters long. At both ends of it there are penetrating damage (holes), one of which was shown in a TV documentary.
Part of the wreck lies in very soft clay. There are also sections of the seabed near the wreck with boulders, hard bottom and bedrock. There appears to be a ridge running perpendicular to the ship and under it, roughly where there is damage to the starboard side.
When examining the vessel with scanning sonar, the results indicated that there is an opening in the bow of the vessel.A ROV camera survey confirmed that the vessel's bow ramp was no longer in place but had detached from its hinge brackets and was now lying on its side, leaving an opening into the vessel's car deck.
Other damage to the ship was also documented. There are i.a. deformations on the stern that may be consistent with the stern hitting the bottom first.
Stockholm university's report on the seabed conditions at the accident site was published in November 2021. The report states, among other things, that exposed bedrock has been identified next to where the major damage to the starboard side of the hull are situated. The bedrock appears to consist of an igneous rock. A drill sample taken in 2023 shows that the bedrock consists of gneiss. Stockholm university's report is available via the link below.
DIGITAL MODEL OF ESTONIA.
As part of the assessment of the new information about Estonia, a digital and a physical model have been created.
The purpose of the digital model of MS Estonia is to provide as accurate a general overview as possible of the ship's exterior and the structural and technical characteristics of the ship as it appeared on 27 September 1994.
The model was created in order to develop a physical model of Estonia and to demonstrate the ship during various surveys and in public contexts.
In accordance with an agreement between the prime ministers of Estonia, Finland and Sweden, a temporary Joint Accident Investigation Commission (JAIC) was formed to investigate the accident.
On September 28, 2020, footage was published showing a previously unknown hole in the ship's starboard side. The Estonian Safety Investigation Bureau therefore initiated a preliminary assessment of the new information and requested assistance from the corresponding authorities in Finland and Sweden.
The purpose of the preliminary assessment is to consider whether the new information gives reason to revise the conclusions drawn in the 1997 report, if new investigation measures should be taken and if so which ones.
For further information on the work on the preliminary assessment, Read more see here.
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