D4/2011M The capsizing and sinking of a BIG FLOAT excavator off Virpiniemi in The Bay of Bothnia on 10 July 2011

A BIG FLOAT 16.36 -type floating excavator capsized off Virpiniemi in the Bay of Bothnia on 10 July 2011. The excavator had started to cross the open sea area off Virpiniemi coastguard station to proceed towards the intended job off Hietakari. The excavator was steered by its driver who used continuous tracks and the grab to assist on the journey. After the excavator had reached deeper water, its bow started to go down, and the excavator began to list. The driver tried to straighten the list, but the excavator listed further. Another man who was to participate in the job came to help in a Buster boat; he climbed on the excavator. The bow of the excavator had already sunk deep when the excavator suddenly capsized at 13.55. The men fell into water but they were able to climb on the excavator which was overturned. They used the Buster boat to transfer ashore.

It was not possible to anchor the excavator. In the morning of 12 July 2011, ropes were used to fasten the excavator to the shore so it would not drift into the channel area. The excavator was towed to the coastguard shore on 14 July 2011, from where it was lifted ashore the following day.

The accident was caused by using the excavator against the instructions of the manufacturer. This led to poorer stability of the excavator. Moreover, the driver had not been familiarized with the use of a floating device.

The Safety Investigation Authority recommends that the company only uses as drivers of floating excavators such persons who are qualified to perform the job and has its equipment inspected by the Finnish Transport Safety Agency. It is also recommended that the Finnish Transport Safety Agency make the inspection operations with reference to dredging equipment more efficient.

In addition, the investigators conclude that the recommendations directed to the company owning the excavator which capsized apply to the entire dredging branch if the equipment is used in deep water. In such situations especially the need of training in ship technology and of clear instructions, particularly factors related to stability, have to be taken into account. In addition, it was noticed in connection with the investigation that quality systems are not common within the branch. Introduction of quality systems would improve the safety of the operations.

D4/2011M Report (pdf, 1.03 Mt)