I have watched the press briefing and skimmed the written report. As a fan of the Estonian composer Arvo Pärt, I am indebted to the presenters for providing the correct pronunciation of the syllable
-ärt. (One of the presenters has a similar name.) The nominal author of the report is
Ohutusjuurdluse Keskus, which I shall refer to as OK.
These are my initial impressions, subject to revision upon more detailed examination.
From the Press Briefing
The dynamics of the detachment of the visor were modeled. These support the conclusion that the visor detachment should have pulled open the bow ramp. The physical damage to the bow ramp is consistent with hammering against the forepeak and bulbous bow. Eyewitness testimony claiming both that the ramp was open and that it was closed are not deemed to be inconsistent because the ramp would likely have closed as the ship rolled. Water ingress through the open bow ramp is considered the primary cause of flooding on the car deck.
The mass of the vessel for physics purposes is given as "10,000 plus" tonnes. This should help alleviate the confusion among some posters that the gross tonnage of 15,000 has anything to do with the physics of this study.
Damage to the starboard side was modeled and correlated to the photogrammetric model. I will discuss this in more detail below. Witnesses on the starboard side of the ship did not see any other vessels.
Flooding models were constructed for three scenarios: bow ramp ingress, side impact damage, and both together. The scenario that best fit the foundering timeline was the bow-ramp-only scenario. The both-together scenario actually results in the ship sinking faster than 35 minutes. The side-damage only scenario resulted in the ship not sinking at all. Significant downflooding paths were identified in the ship's ventilation network irrespective of Deck 4 windows, and modeled in the flooding model. There is no need to suppose that water ingress on Deck 4 contributed. The car deck doors were fire doors and were not watertight or weathertight. Lower-deck flooding was observed far from the starboard side damage, counter-indicating flooding from that source. A scenario involving lower-deck flooding from a hull breach does not support the roll behavior observed and in fact would require the ship to stay more fully upright as she foundered. (I agree, and this shows that Anders Björkman is just that much more wrong.) The overall observation of flooding and the numerical flooding model is most consistent with car deck flooding followed by downflooding through ventilation ducts and subsequent weather-deck ingress.
Although evidence is inconclusive, there is physical evidence to indicate some cars were lashed down. The movement of other cars on the car deck can explain some of the scraping sounds heard by witnesses. The various noises reported by witnesses were investigated via modeling and determined to be plausibly caused by the transmission of noise from the banging bow visor through the hull structure.
Many of the survivors do not want the controversy raised again. Most of the witnesses accept the JAIC findings, but disapprove of some of the politically-motivated actions later, such as the attempts to cover the wreck.
Questions
A number of correspondents asked about the BMTIG findings and challenged the OK panel to reconcile their claims with those of the BMTIG. The BMTIG findings rely on an energy formulation, while OK's does not. They are not directly comparable, although both sides have resolved to publish their models and data. The OK panel was asked if they were willing to participate an "official" dialogue with BMTIG. The OK panel indicated they would be willing to discuss their respective findings with anyone, but questioned how an "official" collaboration would proceed. (The cautionary quotes are in deference to the disagreement between the correspondent and the board over what "official" means in this context.)
From the Written Report
In all fairness, the report needs a native English-speaking editor. Much better than the Brandeburg metallurgy report, but still awkward.
The seafloor near the wreck was extensively modeled, sampled, and tested. It is consistent with what is required to cause mechanical damage to shell plating. BMTIG's position, in contrast, seems to be that the seafloor is just mud. "Rocks? What rocks?"
Black markings on the shell plating were tested and found to be natural biological growth.
The photogrammetric model is complete and accurate. This is a detailed model of the shape of the wreck as it currently lies as derived from photographic data.
A finite-element model (FEM) of the ship was prepared and used to model the structural response of the ship using the ship's weight only. The model plausibly accounts for the penetrative damage to the starboard side.
BMTIG sought to create an energy-based model of the entire foundering sequence and an energy-based collision model to describe the damage to the hull. This is not an inappropriate way to do it, but as I suggested above, it requires parameters whose values simply cannot be known because they exercised their influence during the foundering sequence and cannot have been observed. Thus for them to claim it precludes a seabed-contact explanation is inconsistent with how faithful such a model can be.
OK's model is much simpler and incorporates only data that can be known faithfully. More importantly, in their words :—
The objective of the FEM modelling [sic] was not to replicate the damage visible on the wreck today, but to observe how the ship would behave in a theoretical collision with the seabed. (p.105)
In other words, the model was not programmed to produce the observed condition of the hulll. It was programmed only to apply stresses that would result from the structure of the ship resting on the rocky portion of the seabed under its own weight. This is not an energy formulation. This is important for two reasons. First, it is not directly comparable to the BMTIG findings and does not seek to challenge them on the same grounds. Second, the OK model relies on orders of magnitude less guesswork. In fact, the parameters to a weight-only stress model can be known with great precision following the surveys conducted and from the structural plans of the vessel.
The geometry of the observable damage to the starboard side was produced with extremely high fidelity in the FEM. It is now clear to me why BMTIG does not want to talk about rocks—this is clearly a much better supported conclusion. That's how you do it. The OK method uses far fewer unknowns (yet is a completely physically faithful model). It is a stress-only model, which offers much less room for error with no loss of rigor. It considers the lower-boundary case of
zero kinetic energy input and shows that the observed effects are still plausibly produced. It can only go up from there, so there is an affirmative evidence that the smallest values in the envelope credibly reproduce the observed effects with little wiggle room for estimation error or programming error.
This is especially dispositive.
Additional evidence of contact with the rocky portion of the seabed was presented. The ship's rotation in heading as the wreck shifts has its pivot at the starboard damage site. Further, the entire wreck is "hogging" (i.e., drooping at each end), indicating that it was being disproportionately supported at that point. These indicate that the bulk of the wreck's weight is or has been concentrated on the rocky outcropping. This is especially important as it provides an element of consilience in the findings.
The surface collision scenario was considered. Specifically, “There is no available evidence to suggest that the deformation, or any part of it, was caused by an explosion or a collision on surface.” (p.111)
Physical evidence presented to support this conclusion includes the absence of any paint or substance transfer, and the lack of metallurgical evidence of high strain rates. (A sample was retrieved for analysis.) Circumstantial evidence in favor includes observations that the dynamic stabilizers were observed in the extended position shortly after the bow visor detachment, but found stowed and undamaged in the wreck. The stabilizers would have stowed automatically as the ship's speed decreased below the threshold of usefulness. Since the starboard stabilizer is in very close proximity to the starboard-side damage, it would have received damage in a collision and would therefore not be able to be stowed.
Although not stated in the report, the opinion offered above in connection with BMTIG's statement that the two holes in the side separated by dents and abrasions "could only be caused by a collision" remains absolute bollocks. It's sheer fantasy. There is no credible collision scenario that causes an initial hole, subsequent sliding contact, and then
another hole. OK's comparative analysis is sound while BMTIG's characterizations seem to be mostly wishful thinking.
estonia1994.ee
