The car ferry that caused the Viking Amorella crash in the Hjulgrund narrow-gauge of Åland on the Apteekkarinvaa fairway should not have been on the fairway of the ship.
- The pharmacy fairway has been diagonally measured and bar-raked at the boulder for the last time in the summer of 2009, when the depth of the fairway to 8.5 meters has been ensured, says Simo Kerkelä, Head of the Maritime Fairway Unit.
However, at the request of the Accident Investigation Board, Navy divers who investigated the fairway found a rock that Amorella may have hit on Sunday, September 20, on its way to Stockholm.
The hot question is on which side of the fairway the stone was at the time of the accident: on the safe side of the fairway or outside.
- The stone was found at the edge of the fairway.
It is possible that the stone has moved to its current location for some reason, Kerkelä says.
The stone that tore the bottom of the car ferry is known.
It is four meters long, one and a half to two meters wide and equally high.
At the lowest point, the water is 7.2 meters.
The depth of the fairway is promised 8.5 meters.
Kerkelä raises the possibility that the ship has hit a rock at the side of the fairway and moved it to the place where the divers later found it.
- It is also possible that the ice has moved the stone to the collision site.
Read more: An unrestricted boulder was found at the Amorella accident site - the fairway closed the fairway and investigates how it got there
Judging by the dimensions multiplied by the stone, it is a stone with a volume of 16 cubic meters.
With a specific gravity of granite, the boulder would weigh about 43 tons.
At the limits of whether it should be blown up while on the fairway or moved away with a large dredger.
In water, the stone weighs less than on land due to a phenomenon called buoyancy.
The head of the agency responsible for the sea lanes believes that the stone was not on the ship's fairway.
- When inspection measurements were made on the fairway in 2009, there were no boulders on the fairway, Kerkelä says.
The pharmacy route is narrow at the scene of the accident and lowers quickly outside the route.
There are no underwater rock cliffs near the fairway from which rocks could come off and roll over to the fairway.
At the scene of the accident, the waterway has been dredged, but it has not been blasted and thus did not cause cracks in the rock.
In Åland, there is a variation of granite, reddish rapa stone, which, as the name implies, erodes or crumbles into coarse gravel.
The bottom of the fairway is a moraine block hole where the height ratios vary.
Ships driving in a narrow fairway cause strong currents that could theoretically cause the moraine bed to collapse at the edges of the fairway and the boulders to move over the decades.
However, there are no signs of such.
- There is no observation of erosion on site, Kerkelä says.
The collision of a ship is very likely to be registered in the VDR (Voyage Data Recorder) system, in aviation terms, the “black box” of the ship, as well as the response of the crew to the collision.
This information is likely to be used to determine the position of the ship at the time of the collision.
The information can be compared to the place where the divers located the rock.
This will make it clear if the ship or rock was in the wrong place at the time of the accident.
As a precaution, Traficom closed the fairway after the accident.
With these prospects, it will reopen on Wednesday.