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SSPA Sweden AB produces another manipulated 'Estonia' Model Test Report (Report no. 4006 4100-2)! (uppdated 25 August 2007) In 1995 SSPA Sweden AB produced a manipulated 'Estonia' model test report to show big wave impact forces acting on the visor (when there were none!). 31 May 2007 SSPA Sweden AB produced a second such report (Report no. 4006 4100-2) with completely misleading conclusions about water inflow into the 'Estonia' superstructure after the visor was lost and what happens. The ship model was self propelled and manually radio controlled and allowed to run into irregular head waves (Hs = 4.2 m) at speed 14.5 knots with open ramp. So far so good! - Not to risk that the ship model would capsize (heel 180°) starting at 37° heel with 1800 tons of water (full scale) loaded on the car deck and to pitch/trim too much, an additional 100% buoyant superstructure (0% permeability) was added full length on deck 4 on top of the car deck superstructure decks 2-4. In reality a deck house with windows and doors is located on deck 4-8, which does not provide any buoyancy at any time! It fills immediately with water when submerged. Proper means to prevent the model to capsize and protect instruments and equipment inside the model should allow the model to heel to 80° when capsize can be stopped. Equipment/instruments can be protected by plastic bags. -The model ramp could not have been properly scaled - apparently it was too light. It was seen to close 'now and then' during the tests; a 16 ton full scale steel ramp would have permanently fallen down below the waves and been acting as a plough forcing water into the superstructure all the time. - Probably the permeability of the car deck superstructure space was not done correctly, i.e. 100% permeability forward where no cargo was loaded and about 60% where trucks and cars midship and aft occupied the space. More water should have accumulated forward during the tests. The model was therefore seriously flawed. A correct model should have been permitted to pitch/trim freely at any angle of heel and to heel until at least 80° when some means to prevent further heeling - capsize 180° heel - would be activated. Two runs were performed. The responsible persons, Claes Källström and Björn Allenström, conclude: In both cases the model heeled about 15° after about half a minute full scale time (600 tons of water on the car deck) and 25° after one minute full scale time (1200 tons of water on the car deck). "The ship model got a final heel angle of about 46-47 degrees after about 3-4 minutes". Comments: The reason for the 40% reduced water inflow (1200 tons/min versus expected >2000 tons/min as per previous tests) is that the model ramp was closed, 'now and then' (sic), during the tests. There is no doubt that the ship model would have trimmed
several metres on the bow and capsized at 37° heel
caused by 1800 tons of water on the car deck after only one
minute and then turned 180° turtle and floated upside
down. This was only prevented by the extra 100% buoyancy
fitted on top of deck 4 of the model and the incorrect
permeability of the car deck space deck 2. The time delay
was due to the model ramp reducing
inflow. The reason, why the report does not say
when the the critical heel angle 37°
(or slightly less) occurs during the tests and
what happens then, is that then the model
suddenly heels much more, >47°, it
capsizes, but the capsize and trimming on the bow
are prevented by the additional 100% buoyant
superstructure on top of deck 4. The observation that the ship model got a final
heel of about 46-47 degrees (3000 tons of water on
the car deck) after about 3-4 minutes has therefore
no relevance as that condition is not stable!
Stability is then only provided by the extra
100% buoyancy on top of deck 4 that does not exist
in reality. See photo right! The responsible persons, Claes
Källström and Björn
Allenström, further conclude: "After that the model was filled with (3000
tons of) water on car deck it was left drifting in
the waves. … The drift speed in the waves was
measured to about one knot (full scale). It can be
assumed that if wind had been added the drift speed
would have been about twice". Comments: Question: Why does SSPA Sweden AB produce such misleading findings? No big bow trim or capsize at 37° heel but a stable condition with 46-47° heel (sic) and big stern trim and then drifting with a speed 2 knots (sic)!
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