by Prof. Dr.-Ing. Stefan Krüger and Dipl.-Ing. Felix-Ingo Kehren
The Institute of Ship Design and Ship Safety at TU-Hamburg-Harburg later became the research center Maritime Systeme of Hamburg University of Technology SSI-TUHH.
If you June 2022 searched for their 2007 report about the M/V Estonia sinking 1994 you found nothing, a reader of mine told me recently! Reason is shown below.
So July 2022 I asked Prof. Dr.-Ing. Stefan Krüger, where his 2007 paper was, and he replied at once: Look at https://www.tuhh.de/t3resources/ssi/Veroeffentlichungen/2008/ResearchProject2008KruegerKehren.pdf
where we read:
"From the previous work packages, it was concluded that in the time slot between 01:00h and 01:02h Local Estonian Time, two or three metallic bangs were heard by several passengers and crew members at different locations on MV Estonia. Our investigations have connected these metallic bangs with loss of the water tight integrity of the Main Car Deck #2+ of the ferry. In the following minutes, the amount of about 1500t of sea water accumulated on Main Car Deck #2+ and lead to a quasi-statically equilibrium floating condition of about 30° list to Starboard Side. This list was in line with the reports of the surviving witnesses. The water entered via the bow opening, but is to be assumed that a certain, but unknown amount of water has already been on the Main Car Deck before."
Aha! And this was news to me. Because after that MV Estonia was upright again (0° list) with 1500t water in the superstructure, so that >300 persons could reach open decks during 10 minutes and half of them survive, and how it happened Krüger doesn't know then and today.
"Metallic bangs" were heard, but according JAIC it was loud "wave impacts" that just hit the bow smashed off the visor, which are completely different. And no action was taken. But luckily MV Estonia floated on its deck house decks #5-8, windows of which were watertight.(sic) Etc, etc!
It is not easy to falsify a scientific report! And I wonder today, if this 2022 report is the same, I reviewed 2007. It seems the 2022 report has been rewritten and is completely different from the 2007 report, that I reviewed!! Let's have a look.
Both reports 2007 and 2022 are of course very poor as the basic assumption of the report 2007 is incorrect (page 66):
"Note, that the superstructure (sic) of MV Estonia is assumed as watertight - in the beginning of this investigation. This has the conseqcuence, that the superstructure gives a supporting buoyancy. All calculations carried out in the scenarios in Chapter 7 consequently express the lowest possible heeling angle - in other words the scenarios are calculated in a conservative way (sic). The lever arm in Figure 5.7 shows this distinctively."
The scientists Krüger and Kehren do not know the difference between a real superstructure (the enclosed, weather tight structure decks #2/4 without windows above the watertight, subdivided hull deck #0/2 and high above the waterline between the main deck (deck #2) on top of the hull and the freeboard deck (deck 4) on top of the superstructure of MV Estonia) and a non-weather tight deck house (decks #4-9) on top of the freeboard deck #4 (the structure above deck #4), the latter that cannot be included in any stability calculation, as it does not provide any buoyancy. They thus include the deck house in the superstructure and make the whole vessel watertight up to the funnel. They also ignore the fact that vessel had 22 watertight doors in the hull bulkheads decks #0/2 that were not per SOLAS. All watertight doors were always open at sea!
This means that the ferry will neither capsize, nor sink and that the scientists can load 16 000 ton of water on the #2 car deck without sinking the ferry in its main scenario 1! (page 79):
"8.3 Scenario 1
In scenario No.1 the investigation is focused on the heeling behaviour with water on Main Car Deck, Deck 4 (sic)
A pre-heel of MV Estonia assumed to 1.22° to Starboard-Side - a heel of 1° to 3° is mentioned in several testimonies. The calculation carried out containing water on Main Car Deck in 50t steps up to 2000t, in 100t steps to 3000t, 250t steps to 10000t and up to 16000t in 1000t steps."
The scientists do not seem to know that ships capsize (floats upside down) with water loaded in the superstructure on the Main Car Deck, CD, (deck no. 2 of the MV Estonia) and that the MV Estonia capsizes with only 2 000 tons of water loaded there (because GZ<0 for any angle of heel) due to lost visor/open bow ramp and no buoyancy in the deck house deck 4 upward as per below figure (where LCG of water is 59 meters from AP and trim is ignored):
Intact vessel with intact superstructure has positive GZ until 60° heel. It is not 100% correct as the superstructure starts to flood through open ventilation openings on deck 4, when it becomes submerged at heel angle is 38°, but if the ventilation opening is considered weather tight you can heel to 60°.
500 tons on Car Deck (top of hull) heel vessel 13° and then GZ>0 until 37° heel, when the superstructure starts to flood thourgh venilation openings. 1 000 tons on Car Deck heel vessel 23° and then GZ>0 until 36° heel when the superstructure starts to flood through venilation openings. 2 000 tons on Car Deck heel vessel 36° and then GZ<0, so heel continues to 180° = capsize and vessel floating upside down.
(GZ on vertical axis, heel angle on horizontal axis)
Free water forced into and on a car deck also trims the vessel (it will capsize already with 1 900 tons on #2 Car Deck due to trim) and will evidently flow out through any openings in the superstructure (e.g. an open bow ramp), when the vessel stops and has not capsized previously. Krüger and Kehren prevents capsize by making the deck house watertight and assume in the calculations that the free water on #2 deck does not trim the ship (the free water LCG is magically exactly 59 meters from the aft perpendicular and does not move even if the deck is not level in longitudinal direction)!
So Krüger and Kehren (page 103) load 16 000 tons on the Car Deck and the mean draft is 10.12 meters ... and the heel is only 9.59°! Actually the vessel would have sunk long before that. Then there are 17 other scenarios of all kinds ... and the vessel never sinks and never heels a lot. The hull is assumed intact!
Krüger and Kehren carefully avoids to study the most obvious scenario = vessel's hull is leaking below waterline, watertight doors are open = sudden loss of intact stability with say 600 tons of water on deck no. 0 as witnessed by crew and stable heel <12° (allowing evacuation for 10 minutes), heel increasing when a leaking aft ramp comes under water flooding deck no. 2 aft = sinking as witnessed by survivors. All testimonies by survivors to the effect that the MV Estonia was leaking below waterline are conveniently ignored by Krüger and Kehren!
Thus the report is of no value for serious research into the sinking of MV Estonia and for better safety at sea in general. I assume it is the reason why the 2007 report was removed and lately, 2022, was replaced by something else.
Strange story, to say the least.