C4+C5/2006M M/S HOBURGEN on 7.10.2006 and M/T ARCTICA on 14.10.2006, ramming of edge mark Tröskeln Östra

This investigation report involves two separate instances of vessels ramming the very same deep-water route edge mark, southwest of the Åland Islands in the northern Baltic Sea.

The Bahamas-flagged Ro-Ro freighter M/S HOBURGEN, enroute from Rauma, Finland, to Beirut, rammed edge mark Tröskeln Östra in the Åland Sea on 7 October 2006 at 21:53. Due to traffic the vessel had changed course towards the port side of the deep-water route. At the last moment the Officer of the Watch (OOW) tried to change course but the port side of the superstructure of the HOBURGEN hit the edge mark. The radar reflector and the lighting equipment of the edge mark were destroyed and its helicopter platform (helideck) fell to the sea. What was left of the edge mark above the surface were three metres of the steel frame. The vessel sustained small holes, dents and abrasions above the waterline. However, there were no leaks.

A week later, on 14 October 2006 at 05:40, the Netherlands Antilles-flagged product tanker M/T ARCTICA, sailing with water ballast from Zelzate to Rauma rammed the stump of Tröskeln Östra, which the HOBURGEN had damaged the week before. This happened because the mate was concentrating on monitoring and analysing other traffic. The frame tube of the edge mark was further bent and the vessel sustained a tear on the starboard side of her bow above the waterline. The ARCTICA radioed that she did not require any assistance.

Neither instance involved any malfunctions or shortcomings in the vessels’ equipment. As regards the HOBURGEN ramming, it is evident that there were shortcomings in the lighting and functioning of Tröskeln Östra, which made it extremely difficult for the ARCTICA to spot the stump of the frame.

Vessel Traffic Service (VTS) records of the accidents show that virtually all vessels sailing in this zone either fail to make a voyage plan in accordance with the traffic in the deep-water route or ignore the voyage plan if it is made. This results in unpredictability in navigation practices, creating traffic safety risks. Vessel traffic in its present form in the zone highlights the importance of an attentive look-out on the bridge.

The investigators believe that imprudent and unpredictable navigation practices, caused by unorganized traffic, as well as the absence of a look-out from the navigational team on the bridge contributed to the accidents of the HOBURGEN and the ARCTICA.

During the investigation VTS records showed that in the Automatic Identification System (AIS) message of one vessel the heading information was approximately 60 degrees in error. Two different displays possible for this erroneous data facilitated two completely dissimilar (different) information contents for the vessel motion (at s single point of time) in the two recordings available for the investigators.

The investigation commission recommends that, as soon as possible, improvements in traffic arrangements in the sea area should be carried out according to the the Åland Sea traffic separation scheme, proposed to the International Maritime Organization (IMO) and also the establishment of traffic monitoring there.

Users must be made aware of the possible misleading display modes of AIS information in electronic chart displays concerning target heading and speed. The investigation commission recommends that the Finnish Maritime Administration warn Finnish shipping, and inform the IMO, of the dangerous display modes in AIS messages.

When it comes to close proximity multi-vessel traffic situations in relatively narrow fairways, manoeuvring and any possible action taken to avoid collision in high-risk conditions shall be made with due regard to the observance of good seamanship and under the International Regulations for Preventing Collisions at Sea (Rules of the Road). In such conditions the look-out should never be excused from his duties.

C4+C5/2006M Report (pdf, 1.76 Mt)