The Dutch Safety Board has published the report of its investigation into an accident in which a crew member died after being hit by a breaking stern line. It involved the Dutch cargo vessel Damsterdijk. Findings include that crew tasked with supervising should not carry out other tasks and the Ministry of Infrastructure and Water Management has been asked to look into this.

Accidents with mooring lines in the maritime industry are unfortunately common and often serious. When such a line breaks, it snaps back with such force that it can be deadly upon impact. The Dutch Safety Board now releases recommendations after the accident with the Damsterdijk, which it also did in November 2020 after releasing a report about a similar accident involving the RN Privodino.

The Board stresses that the advice given in this instance, also holds true for the Damsterdijk: to work from a safe location instead of having to enter unsafe snap-back zones. To achieve that objective, in areas with snap-back zones, safe workstations should be identified or created where those aboard cannot be hit by mooring lines and ropes if they snap back. These safe workstations should be marked in a recognisable manner and the work processes involving mooring lines and ropes should be organised in such a way that operations are always undertaken from these safe workstations.

However, the accident with the Damsterdijk also uncovered a different contributive factor that needs to be dealt with, namelijk assigning tasks to a crew member that is also charged with supervision, either of the entire operation or of a cadet.

Damsterdijk accident

The fatal accident on board the Damsterdijk took place on 2 October 2019 in the port of Ipswich (UK). The ship operates under the management of Shipping Company Groningen (SCG). While in port, the vessel had to be moved backwards over a distance of approximately 100 metres, in order to make space for another vessel. While the ship was being moved, the stern line ended up in the propeller.

As a result, the line came under tension and broke. Part of the line snapped back, hitting the cook/AB at high speed. The cook/AB was seriously injured and later that day died as a result of those injuries.

Combination of tasks and roles

The direct cause of the accident was the entanglement of the stern line in the propeller, which caused the line to come under tension and subsequently break. A number of underlying factors contributed to the occurrence of the accident. First of all, several crew members had different tasks and roles at once.

The mooring and unmooring procedure specifies a crew composition for the aft deck, whereby the responsible able seaman (AB) is required to supervise the other crew members, their work, the correct passing on of commands and the communication with the captain. The procedure also states that the AB himself is actively involved in handling the mooring lines. As a consequence of this combination of tasks, it was not possible for the AB to maintain an overview and ensure supervision of the various actions on the aft deck; moreover, he was unable to issue a timely warning when the unsafe situation arose.

This same combination of tasks applied to the cook/AB because he combined his own work with giving instructions to an inexperienced cadet. The standard working method was deviated from when the cadet was added to the team on the aft deck, as part of his training. The work on the aft deck was new to the cadet.

The Dutch Safety Board states that a safety management system can only actively contribute to increasing safety if it is in line with the practice on board and if the crew members are sufficiently safety-aware and safety-competent. A crew member charged with supervising safety cannot perform other duties in addition.

Communication and fatigue

The stern line became entangled in the ship’s propeller due to lack of clear communication, says the Board. The cook/AB was not issued with a walkie-talkie, and the AB in charge was beyond his field of vision and out of hearing due to the noise of the engines. The cook/AB was not aware that the ship was not yet in position. The two stern lines were paid out without the captain’s command and at the same moment that the vessel once again started moving backwards.

In addition, the AB was found to not have taken sufficient rest hours prior to the incident. This may have influenced his actions and his supervisory role.

Snap-back zone

As the ship would only move a short distance, it was decided to leave the mooring lines loose on deck instead of coiling them around the storage drums during the manoeuvre, despite them now posing a trip/fall hazard. As a result, the working deck was not clean and the mooring lines were able to enter the water unhindered, at high speed.

The cook/AB came in the snap-back zone when he tried to stop the starboard stern line from going overboard. This zone was not marked as such, or clearly indicated with signals.

Omission in the manning plan

The manning plan submitted to the Dutch Human Environment and Transport Inspectorate (ILT) by the ship manager included a mooring and unmooring procedure, which assumed more crew members than the number applied for by the ship manager for the accompanying safe manning certificate. Further investigation at the ILT has revealed an omission, as a result of which a proper assessment of the manning plan was not made before the safe manning certificate was issued.

The working method in the manning plan, based on nine crew members, could not be carried out by the crew members actually present (there were eight crew members on board).


According to the Safety Board, safety deficiencies underlie the aforementioned underlying causes. In order to learn from them, various recommendations are made.

The shipping company should ensure crew get enough rest, should require all crew members on board to use walkie-talkies and should ensure a clear warning method for working in and near a snap-back zone.

The Ministry of Infrastructure and Water Management should ensure that the manning proposed in a submitted manning plan is always checked for feasibility with regard to the work to be carried out, type of ship, safety procedures and emergency procedures. A safe manning certificate should only be issued if all conditions are met.

The Ministry and the Royal Association of Netherlands Shipowners (KVNR) are urged to investigate together whether the basic principle can be maintained that a crew member charged with the physical supervision of safety can also perform other duties. They should apply the results of this investigation when drawing up manning plans and issuing safe manning certificates.

Safer mooring lines

The Dutch Safety Board does not mention the use of mooring lines with no or reduced snap-back, such as the Snap Back Arrestor (SBA), developed by Wilhelmsen Ships Service. This type of rope has an energy absorbing core. If the outer, load-bearing construction breaks, the SBA absorbs the snap-back forces, transforming them from a potentially deadly snap, to a much safer, slump. This would also significantly reduce mooring line accidents. Shipping company Maersk began implementing this type of mooring line in June 2020.