The government unveiled a memo from experts who visited the video of the dox series made by the ferry from Estonia. Its authors are Kristjan Tabri, Senior Research Fellow and Doctor of Shipbuilding at Tallinn University of Technology, Märten Vaikmaa, Head of Baltic Workboats, Ingmar Pill, M.Sc. In addition, the memorandum has also been signed by Mart Luik, Adviser to the Foreign Minister who has visited Oslo.
Watching a video of a remote-controlled vehicle filmed by the ferry Estonia
Date and location: 18.09.2020 Oslo, Norway
Observations
On the starboard side of the ferry Estonia, a video filmed using a remote-controlled vehicle was shown together with another video, during which the findings were interpreted by a remote-controlled vehicle expert and a shipbuilder professor.
Initially, these videos were shown for the general public on September 28th. The video begins with the claim that after accident, the ferry Estonia was at an angle of 120 degrees to the seabed and now has a heeling angle increased to 132 degrees, see figure below. Thus, the starboard side of the vessel is partially up from the seabed elevated and the starboard port can be explored by remote control vehicle.
In the videos, the remote-controlled vehicle moved along the hull, seemingly heading from the bow to the center of the ship. The camera was essentially moving along the collision beam, ie at the same height as the car deck.
Red in the figure below crushing damage No. 1 appeared in the area marked with a cross / line. The damage was allegedly located on the ship about 98 meters from the stern, although a more realistic value seems to be about 90 meters.
The penetration depth was alleged to be about 1.2 meters, revealing an obvious gap in the hull. There was a gap a relatively straight vertical line about 4 meters high. The gap seemed to run stronger a structural element such as a frame arch. According to the ship's profile view, the gap extended from the car deck to the intermediate deck (Deck 1 / Tween-deck in the figure below). In the middle of the vertical gap, approximately at the location of the impact beam and the car deck, the gap also widened horizontally. Its length is not directly stated, but it appeared to be about 1 meter. The direction of penetration pointed slightly towards the bow. The shape of the penetration seemed to be triangular, more so irregular as symmetrical in nature. The narrow steel strip was bent outwards from the hull. Remotely controlled 3D models of the opening and the gap caused by the damage were made on the basis of the images obtained by the vehicle.
No obvious longitudinal scratch marks were observed in the vicinity of the damage opening.
Although very little of the seabed was visible in the video, the bottom appeared relatively hard and smooth with no visible larger stones.
In another video, Professor Amdahl from NTNU made a simple structural assessment and claimed that such damage the force required to generate it is around 500-1000 tonnes.
Unofficially, we were briefly shown an unedited frame filmed with a remote-controlled vehicle that does not belong for immediate publication. At the same time, a significant additional was presented in the shots filmed with the remote-controlled vehicle evidence. The seabed was clearly visible, and at least one section also showed larger rock assemblages. The video also covered the seabed next to the ship where after the accident it was stacked with stones.
Moving towards the stern of the ship, another opening appeared at the other end of the ESTLINE text (marked with a horizontal orange line). The plate was torn open, probably along the longitudinal direction weld. The arches were torn from the weld and clearly visible. No dents were observed and the load appeared to be more evenly distributed compared to the first lesion, where the local dent was clearly visible.
Possible causes / interpretation
(This discussion does not address the second lesion and focuses only on local penetration lesion # 1)
Penetration damage No. 1 is caused by a force or object left outside the ship, denting the ship side structure. The steel plate was bent inward, except for a narrow strip of steel which bent outside.
The properties of the dent and the penetration damage are not typical of either explosive or man-made cutting gap.
It is unlikely that the damage was caused by a collision at sea level.
Penetration damage
The direction of the dent pointed slightly toward the bow. A penetrating object should have been caused to cause such an injury approach the vessel from the stern, oblique to the direction of the ferry Estonia (approximately 45 degrees). It would be, too the speed of the penetrating object must have exceeded the speed of the ferry Estonia.
A possible explanation for such damage may be contact with an underwater object, such as the seabed with a stone. The weight of the vessel (12 000 tonnes) significantly exceeds the force required to form a
salmon (?) (500-1000 tonnes)
Thus, the uneven surface under the side of the vessel can create concentrated forces that can cause penetration damage.
The 1994 survey report shows the lateral position of the vessel on the seabed, see below. See the position indicates that the slope of the seabed changes from the bow to about 1/3 of the length of the vessel. Such a slope the change will result in a higher load in the area where the damage shown in the video was seen.
In no scenario can the magnitude of the visible damage be the cause, why the ship sank in a period known to us.
Proposals
The results cannot change the conclusions of the JAIC final report, as there can be no gap of this size the reason why the ferry Estonia sank to the seabed within a period known to us. So it doesn't seem further investigation to determine the cause of the sinking of the ferry Estonia is reasonable. However, further investigation may reveal local penetration damage causes.
A detailed scan or video of the seabed may reveal whether it is on the seabed stones the size needed to cause damage (unofficial video showed that there are such rocks on the seabed).
Although there are relatively good shots of damage, divers can do damage to get even more accurate information when measuring and scanning.
To analyze and elucidate local penetration damage on the seabed can be performed numerical simulations. Possible scenarios could be drawn up to rule out a collision scenario at sea level scenarios that could be associated with the observed damage (ferry Estonia and penetrating the relative directions and velocities of the object and the required mass of the penetrating object determination). This would make it possible to assess whether such a collision scenario would exist and be theoretically possible.
Kristjan Tabri, TalTech / MEC Engineering Solutions
Tauri Roosipuu, TalTech EMERA
Märten Vaikma, BWB
Ingmar Pill, BWB
Mart Luik, Ministry of Foreign Affairs
P.S. Professor Jaan Metsaveer, a former member of JAIC, has already seen the video before us and asked to direct it notes that it agrees with and supports the conclusions reached here.
Lähde:
https://www.err.ee/1142322/ekspertide-m ... ud-videost