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Välkommen till ett kapitel ur e-boken Katastrofutredning. |
Appendix 1The writer was invited to the Design for Safety Conference at Glasgow 1999: The below paper was presented:
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Estonian
Time |
Time after Loss of Visor (min) |
Water in the Super-structure as per Huss (tons) |
Inflow as per Huss (tons/ minute) |
List as per Huss (degrees) |
Wave Direction (°) |
List as per Final Report (degrees) |
Velocity of Heel (degrees per min) based on (5) |
Diff. in List between Huss and Final Report |
Speed acc. Huss (knots) |
Speed acc. Final report (knots) |
|
01.14.00 |
0.0 |
0 |
400.0 |
0 |
135 |
0 |
15.0 |
0 |
14.5 |
14.0 |
|
01.14.30 |
0.5 |
200 |
400.0 |
6 |
135 |
- |
15.0 |
- |
14.5 |
~ |
|
01.15.00 |
1.0 |
(340) |
285.7 |
(10) |
~ |
15 |
15.0 |
(+5) |
~ |
~ |
|
01.15.12 |
1.2 |
400 |
250.0 |
11 |
150 |
15 |
0 |
+4 |
13.0 |
~ |
|
01.16.00 |
2.0 |
(571) |
250.0 |
(15) |
~ |
15 |
0 |
±0 |
~ |
9.0 |
|
01.16.24 |
2.4 |
700 |
83.3 |
17 |
*180 |
- |
5.0 |
- |
8.5 |
~ |
|
01.20.00 |
6.0 |
1 000 |
38.5 |
22 |
~ |
30 |
5.0 |
+8 |
5.5 |
6.0 |
|
01.22.00 |
8.0 |
(1 077) |
38.5 |
(23) |
~ |
35 |
2.5 |
(+12) |
~ |
4.5 |
|
01.24.00 |
10.0 |
(1 154) |
38.5 |
(24) |
~ |
40 |
2.5 |
(+15) |
~ |
2.1 |
|
01.27.00 |
13.0 |
(1 269) |
38.5 |
(26) |
~ |
(50) |
(3.3) |
(+24) |
~ |
~ |
|
01.30.00 |
16.0 |
(1 385) |
38.5 |
(27) |
~ |
60-70 |
3.3-5.0 |
(+33/43) |
~ |
1.7 |
|
01.33.00 |
19.0 |
1 500 |
55.6 |
29 |
255 |
80 |
6.7 |
+51 |
0.0 |
2.2 |
|
01.40.00 |
26.0 |
(1 888) |
55.6 |
(35) |
255 |
110 |
2.5 |
(+75) |
0.0 |
2.2 |
|
01.42.00 |
28.0 |
2 000 |
55.6 |
37/180! |
255 |
115 |
4.0 |
+78/-65 |
0.0 |
2.2 |
|
01.43.00 |
29.0 |
2 056 |
- |
180!! |
~ |
(119) |
4.0 |
(-61) |
0.0 |
2.2 |
|
01.51.00 |
37.0 |
- |
- |
180!! |
~ |
(150+) |
4.0 |
(-30) |
- |
2.2 |
Expert Huss 'scientifically' established based on model tests, assuming that the ship turned 180° back to Tallinn first into and later away from the waves, that it took 6-19-28 minutes to fill the car deck in the superstructure with 1 000-1 500-2 000 tons of water (inflow 166.7-38.5-55.6 tons/min). In that time the angle of heel increased to 22-29-37 degrees (velocity of heeling 3.67-0.54-0.89 °/min). It took the Estonia 19 minutes to stop in the water at 01.33 hrs according to Huss. Then Huss calculated that the vessel, immobile in the water, scoped up another 500 tons of water on the car deck in the superstructure during 9 minutes (inflow 55.6 tons/min) and capsized at 01.42 hrs. Unfortunately it seems that Huss forgot to consider, that water on the car deck trims the ship - all the water would collect forward and push the bow downwards and increase the inflow, so that the ship would quickly stop, capsize and turn upside down - like the Herald of Free Enterprise. Another suggestion is that the water should have flowed out by itself due to the bow trim, when the ship stopped with 1 000 tons on the car deck and that the ship would upright itself.
However, the official investigation just changed the Huss reconstruction report completely, e.g. it first stopped the water inflow between 01.15 and 01.16 hrs to enable the survivors to evacuate the ship. Then more water was added on the car deck in the superstructure, but the trim was ignored. It is shown, without any scientific base, that the angle of heel increased to 40 degrees in 10 minutes, to 60-70 degrees after 16 minutes and to 110 degrees at 01.40 hrs, as a result of allegedly increasing amounts of water on top of the car deck. The water on the car deck increased to 600-1 400-2 100->4 000 tons of water in 2-6-10-16 minutes, but the ship's speed never stopped, even if the car deck was filled with > 4 000 tons of water - the speed was 2.2 knots when the ship sank, which was physically impossible. Ships stop, when filled with water and when the engines are stopped.
The falsification of the Huss data by the investigators is easy to demonstrate. Huss computed, based on model tests, that only 2 000 tons of water could have entered the car deck in the superstructure 2,5 meter above the waterline in 28 minutes. The average inflow was about 71,4 tons/min. Without any scientific base at all the official investigators changed the data and stated that >4 000 tons flowed into superstructure in only 16 minutes. The average inflow was >250 ton/min, which is more than 3 times the inflow rate from Huss model tests! According all model tests the inflow never exceeded 55 tons/min, when the bow was pointing away from the waves and the speed was less than 5 knots. How the hull was filled with water neither Huss nor the official investigators explained.
The official report says that the ship sank at about 01.51 hrs, but the time is not proven - the ship may have disappeared earlier. It is also assumed, that it is proven, that the Estonia should have turned 180 degrees after the accident back to Tallinn. Assisting ships however noted that the Estonia was almost immobile in the water when Mayday was sent 01.24-01.30 hrs (close to the sinking position). The Final Report chapter 12.5 states that it has been discovered by sonar investigations of fragments on the seabed, that the Estonia made a port turn after the visor was lost. What the fragments are and why they fell off the ship half a mile west of the visor has never been stated. According to media reports in October 1994 the 'fragments' were found East and South of the wreck - 3 000 metres away from the turning point! According to the official report the ship had >4 000 ton of water on the car deck at 01.30 and should have trimmed >3 meter on the bow and should have capsized much earlier. According to the official report the sinking ship moved sideways about 700 meter to NNE between 01.40 hrs, list 115 degrees, and 01.50 hrs, when the ship sank. It is of course not possible that a sinking ship moves with 2.2 knots speed. According Huss the speed was zero already at 01.33 hrs.
Thus - Dr. Huss tried to reconstruct the accident with water on the car deck in the superstructure but his times did not tally with the actual sinking. According Huss the vessel should have stopped after 19 minutes and capsized after 28 minutes. The writer thinks the ship should have capsized and stopped after one minute and floated upside down on the undamaged hull. However - the official report changed the times, heel angles and water inflow of the Huss report to tally with observed times and heel angles, but then the data do not make physical sense. In spite of the fact that the official report increased the average inflow rate more than three times, it took the vessel 37 minutes to sink without capsizing. The errors are obvious. So neither Huss nor the investigators could explain how the hull was filled with water.
Conclusions
The official Final Report of the Estonia accident contains many errors.
· The suggested accident time history - figure 13.2 - evidently cannot be correct.· The bow ramp was probably never open during the accident but was only leaking, so little water entered there. The ship did not sink due to water on the car deck.
· The ship probably sailed with all watertight doors open; the watertight doors were never closed when the ship sprang a leak, so the ship sank due to open watertight doors. This suggestion has not been investigated.
· The ship sank very quickly on the stern. It would appear that a leak aft below the waterline sank the ship. This suggestion has never been investigated.
Recommendations
I strongly recommend that the investigation into the sinking of the Estonia be reopened (as already requested by the ITF, 32 Swedish survivors and many others). I recommend that a new underwater survey be done to establish that the ramp was closed, the watertight doors were open and that there is a hull damage, which sank the ship. I recommend that Bureau Veritas and the Estonian maritime administration open their records, so that it can be confirmed that the watertight door system did not comply with SOLAS. I finally recommend that the IMO review its latest rule changes, which were only adopted as a panic reaction, based on the wrong assumption, that water on the car deck caused the Estonia accident.
About the Writer
Mr Anders Björkman graduated from Chalmers University of Technology in 1969 with a M.Sc. in Naval Architecture and Marine Engineering. He spent a year in the Royal Navy i.a. with conversions of ferries and other ships into minelayers. Mr. Bjorkman has worked for Lloyd's Register as a class surveyor and for Scandinavian Underwriters Agency as an underwriter's surveyor. Since 1989 Mr Björkman has assisted the El Salam shipping company, Cairo, Egypt to be the leading roro-passenger shipping company in the Red Sea and lately the Mediterranean with today 14 roro-passenger ships transporting > 1 000 000 persons annually. When the Estonia sank Mr Björkman evidently immediately started his own investigation into the sinking, as per Company ISM instructions, so that similar accidents would not occur in his own fleet. The findings have been published in book form and received good reviews by, e.g. the Naval Architect magazine and national newspapers. The findings were brought to the attention of many maritime administrations and the IMO in 1997.
Mr. Björkman has developed the Coulombi Egg oil tanker protection system, which is the only alternative design system to double hull according to Marpol I/13F(5) approved by the IMO in 1997. It is the only ship design purely developed according to damage statistics and FSA.
Mr Björkman has made many written contributions about ship's safety and works as a ship safety consultant.
Appendix
I will here summarise my ideas how the Estonia accident took place. My observations are based on talks with three survivors, with the German Group of experts, with the official investigators Huss, Karppinen, Stenström, Forssberg, Schager and Eksborg and on basic stability and floatability theories and steering performance data of my own roro-passengerships.
Most survivors suggest that the ship experienced a number of heavy impacts before the sudden loss of stability, i.e. when the time was 00.50-01.00 hrs. Most survivors suggest that the ship suddenly lost its stability at about 01.02 hrs and heeled 40-50 degrees to starboard. Lose furniture and persons not holding on to fixed objects were thrown down into the lee. Many persons broke arms and legs. Most survivors agree that the vessel then uprighted, but not to even keel but only to about 15 degrees list at say about 01.05 hrs, and that the ship remained stable in that position for a few minutes enabling people to get out. Most survivors agree that the vessel then heeled and ended up on the side while trimming on the stern, i.e. the ship sank with the stern first. Most survivors had to jump into the water from the upper decks at abt. 01.25-01.35 hrs, some survivors walked out on the flat side and down to the bilge keel and jumped into the sea from there when the ship superstructure sank below the water, say at 01.35 hrs.
I am fully aware of several testimonies to the effect that the sauna on deck 0 forward was flooded and that water spilled up on deck 1 forward, where it was observed. However, assuming that the watertight doors to the adjacent spaces (conference rooms) were closed, the ship would not sink due to a flooded sauna space. If water had spread to several spaces forward, the vessel should have sunk bow first, and this did not happen.
Based on the simple observation that the ship sank stern first, I think that there was a leak aft and that three or more compartments aft below the car deck (the stores) were quickly flooded already 00.50 hrs, that this caused the loss of initial stability (GM<0) at 01.02 hrs and the sudden heeling, but that the ship retained stability at 15° list due to positive righting arm (GZ>0) at that list. Then the ship sank, stern first.
The vessel turned to port already at 01.02 hrs to counter the list. At 01.16 hrs the heel angle was 50 degrees and the visor was lost, but then the ship had already turned about 135° and was already almost heading back to Tallinn. During the turn the port engine stopped first at its propeller came out of the water. Soon after the starboard engine stopped and the ship was un-steerable. The ship virtually stopped 300-400 meters from the sinking (wreck) position at 01.25-01.30 hrs, when the Mayday was sent. The ship then slowly drifted - speed 0.3 knots - to the (wreck) position where she sank.
The course of events is shown in the below reconstruction of the accident. The times, the positions of the visor and the wreck and the ship at 01.25/30 hrs, when Mayday was sent, and the turn to port between 01.02/25 hrs make sense. Also the timing of the sinking makes sense - the inflow of water through a hole below waterline was say about 150 tons/min and spread through open watertight doors to several watertight compartments below the car deck. After 30-40 minutes all buoyancy aft below the car deck was lost; the superstructure was immediately flooded so that the ship sank - stern first. The car deck was still intact and contained buoyancy, but it was not sufficient to keep the ship afloat.
(Note 22 February 2001 - apparently the position of the visor shown below is false - the visor was attached to the ship when it sank. But it does not make this reconstruction less interesting. New information indicates that the ship had another course at the accident - towards Sandhamn, listed suddenly at 01.02 hrs and then just stopped. The visor was not properly locked and was ripped partly off during the sinking. Thus - the visor could not have caused the accident).
The shaded one square mile around the wreck is the diving exclusion zone proclaimed by Estonia, Finland and Sweden and accepted by Denmark and United Kingdom.

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