A new Report 2007 about the M/V Estonia Sinking - the deck house was watertight, etc, etc., and M/V Estonia was unsinkable

reviewed by Anders Björkman

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A new Report about the MV Estonia Sinking (part of the Vinnova study 2006-2008) has been published 2007 by the Institute of Ship Design and Ship Safety at TU-Hamburg-Harburg.

"Research Study of Sinking Sequence of MV Estonia "Accident Scenario"

by Prof. Dr.-Ing. Stefan Krüger and Dipl.-Ing. Felix-Ingo Kehren

The report is very poor as the basic assumption of the whole report 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 consequence, 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 without windows above the watertight, subdivided hull 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 on top of the freeboard deck (the structure above deck 4), the latter that cannot be included in any stability calculation as it does not have 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 that were not per SOLAS. All watertight doors were also 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 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 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 deck no. 2 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.

 

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