On December 23 2016 two ships on their way to the scrapyard being towed by the Maersk Battler sank in the Bay of Biscay. There were no injuries but the incident was investigated by the Danish Marine Accident Investigation Board. The report was issued on August 20 2017 and is summarised here.

Photograph of the two ships under tow from the DMAIB Report.

Back in the summer of 2016 the Maersk Supply Service a subsidiary of the Maersk Company based in Denmark decided to “right size” the company which was to result in the disposal of a number of ships to the breakers, and additionally the reduction in staff by 400 jobs, which were to be distributed between the sea  staff and the shore staff.

The Maersk Shipper and the Maersk Searcher were sold to the shipyard at Alaiga in Turkey for recycling and in August preparations were made for the towing of the ships to the breakers, using the company’s own expertise. It was after all what they thought they were good at.

In September there was a meeting designated a Management of Change (MoC) meeting involving members of a number of departments, commercial, HSEQ, nautical and operations. The two ships were to be towed by a third ship the Maersk Chancellor. Three possible methods of carrying out the tow were considered, since the objective was to do the job using one ship and one crew. The first was a “double tow” which involved two tow wires from the towing vessel one to each towed ships one astern of the other. The second possibility was a “serial tow” where the towing vessel would be connected to the first of the towed vessels which in turn would be connected by the second towed vessel. And the third technique would be the towing of the two vessels side by side.

A marine superintendent was given the task of preparing procedures using the serial tow method but it became evident that this method would require an additional crew on the first of the towed vessels and so he was encouraged to investigate the side by side method, which would not require the additional crew. So while this possibility was being investigated a team in Fredericia began to prepare the ships for side by side tow. The Maersk Chancellor was on its way from Canada, and the company had applied for a waste disposal certificate but this would not be ready when the ship arrived, and so the Maersk Chancellor was given the task of towing the Maersk Beater to the breakers.

In the middle of all this the company decided to issue redundancy notices,  involving the superintendents who had been in charge of the S Class tow, but because the management chose to push everybody out of the building, as tends to happen these days, they were unable to hand over their partially completed work to anybody. Then there were further organisational changes which the DMAIB report describes as “a large scale rotation”, and the tow job became the responsibility of the new European operations team.

By early December since the Maersk Chancellor was on its way to the breakers the Maersk Battler was given the task of the side by side tow, and so it was dispatched from Aberdeen on December 4 2016.

The preparations for the tow were mainly supervised by a “shipping trainee”, and the new operations team were under to impression that the towing arrangements had been approved months before. A further meeting took place on December 7 where a number of routine items were discussed and a risk assessment was carried out.

And now things get a bit complicated. On December 9 the former operations manager was in contact with the shipping trainee and suggested that the insurers needed to be notified and that they should have a copy of the towing procedure, and since no-one now knew about the document it was passed by the former operations manager to the trainee. The shipping trainee then forwarded the document to the insurers saying it was a draft and also forwarded it to the Maersk Battler suggesting they should update it, but this did not reach the ship due to internet problems.

During the weekend of December 11-12 a class surveyor carried out a “fitness for tow” inspection and found the S Class ships fit for tow, and the crew of the Maersk Battler continued to prepare them.


December 12 2016.

1130. The Maersk Battler with the two S Class in tow side by side departs Fredericia proceeding to Skaw Roads for stores.

December 14 2016.

Stores are taken aboard and the tug and tow continue on a southerly course through the North Sea. The Maersk Battler continues to have problems with internet reception and relies on the master receiving weather forecasts on his mobile.

December 20 2016.

The tug and tow are in choppy weather. The tow wire is extended to 630 metres. It is noticed that the fendering between the S Class vessels has disappeared and that there is some contact between them. This is not considered to be a problem since they are to be recycled.

December 21 2016.

During the morning the ship is contacted by Ushant Radio saying that it has been involved in an incident, and since this is not the case the master contacts the company to set things to rights. The towed vessels continue to lean in towards each other and damage to their superstructures continues.

2325. The on watch AB noticed that the Maersk Searcher is lying deeper in the water.

2345. The Maersk Searcher capsizes.

December 22 2016.

0022. The Maersk Searcher sinks and a few minutes later Maersk Shipper capsizes.

0607. The Maersk Shipper sinks.

0616. The Maersk Battler is detached from the tow by going ahead on the engines so as to break the wire.

1730. After contact with the company the Maersk Battler continues on its voyage to the breakers.

January 5 2017.

The Maersk Battler arrives at the breakers.


The investigators started off by looking at the towing procedure, which had been sent in draft to the insurers and to the Maersk Battler, but the ship had not received it. In reality the new operations group had received the draft, possibly draft 7, although the DMAIB were under the impression that version 9 still in draft might have existed. The procedure was incomplete in a number of ways, starting off with lack of information about its purpose. They felt that the “old” group who had been developing the procedure had been using it as a basis for deciding whether the side by side tow would be possible, but by the time the “new” group got it there was an assumption that the side by side tow had been accepted, and so preparations were made by connecting up the two ships side by side.

They then went on to consider the risk assessment which used a form listing possible risks and determining their frequency and consequence and then what control measures might reduce the risk to an acceptable level (OR NOT). What might be seen as the first risk assessment was carried out by the crew of the Maersk Chancellor and then reviewed at each MoC meeting ashore. Some copies of the risk assessments were available to the DMAIB and the report states that the risk assessment determines that collision between the ships got the highest figure but that the provision of fenders and chains reduced it to an acceptable level. Then considered was the possibility of the fendering failing, but the risks were reduced to an acceptable level by suitable securing means and visual observation. The third possibility was flooding of the two towed vessels to which no risk numbers were assigned. The investigators assumed that the assessment was not completed.

The investigators talked to people involved in the operation and it could be said that those in control ashore perceived that the fendering would work and everything would be fine. The crew of the Maersk Battler thought that the fendering would be lost, but that the resulting damage would be more or less superficial, and people involved in the preparation for the tow, probably at a non management level had views which varied between that everything would be fine, to that it would be a disaster.

They then went to look at the approval process, and an approval was gained from the Danish Marine Authority which said that the towed vessels did not require manning but it is pointed out by the investigators that this was not an approval for the tow. And then they reviewed the “Fitness for Tow” survey by class. This inspection and approval only considered the status of the ships, and did not consider the risks of the operation which would be carried out by a warranty surveyor. Everyone involved thought that the approval considered the entire tow, and the report lists the items which were not considered: “the towing method, the fendering and the voyage planning”.

There is a lot of information about the preparation for the tow, and how the ships were connected and fendered to prevent them destroying each other. There was a bridle at the bow and two lengths of chain connecting the sterns, and between the ship three Yokohamas were installed. In the case of this narrative and the information available, the word is used to describe large cylindrical fenders which have been used for years to keep big marine objects apart. In this case the recommended diameter for the three fenders was three metres, but in the end due to expense three second hand fenders of a lesser dimension were used. There is no certainty that the specification or age of the fenders caused them to be lost, but this and the non-recommended means of attachment may have contributed.

Once the fenders had been lost there seems to have been nothing to stop the ships seriously damaging each other and the investigation determined that the damage alongside the accommodation both above the water and possibly below would have allowed the engine rooms to be at least partially filled with water, and as a result the loss of buoyancy and the likely free surface would have resulted in the ships capsizing.

In analysing the causes of the accident the investigators suggested that the option of a “double tow”, one requiring the towing vessel to have two winches available was not available to Maersk initially due to the limitations of the Maersk Chancellor (I am going to disagree with this view later) and hence only the second option the “series tow” or the third option “the side by side tow” were available, and the second tow required two crews,  an option the company were reluctant even to consider. And hence it was considered that even though the Maersk Battler could have fulfilled the “double tow” requirements, it was out of the frame. The further MoC meetings, without input from the management which had been sacked, did not go back to first base and consider the double tow, and the crew of the Maersk Battler accepted that the company management had considered the possible problems but that they “identified themselves with the company image of being industry frontrunners”.

The investigation then went into the details of the risk assessments, and they determined that the shore management of the company left after the sackings did not have the remotest idea what they were dealing with, and so any risk reduction measures were completely aspirational, and not in any way based on actual experience.

In their conclusions there is considerable criticism of the risk assessment process, and suggested that it is prone to one or more individuals subjective risk perception. And they said “The risk management system will rarely limit activities prone to risk. In fact the risk management system instead tends to facilitate the carrying out of risk prone operations”.

The investigator’s report includes a number of initiatives which were to be taken by Maersk subsequent to the accident, and they are more or less as you might expect. They intended to initiate an “Management of Change” training programme, and to improve the risk assessment processes, and they intended to employ a third party expert to review processes where the company is handling its own vessels, and they were to define lines of responsibility and would start an intensive training programme of key personnel.


Words fail me really, and while I agree with almost everything the DMAIB have said, I find myself wondering about the view that the Maersk Chancellor was not equipped to carry out the “double tow”. According to my website all the C Class which were once OIL ships were equipped with two tow drums, and again according to the information I have, which was gleaned from the Maersk Supply website, the Maersk Battler had two work drums and one tow drum, actually making it slightly less suitable than the Maersk Chancellor. In fact any of the Maersk anchor-handlers could have carried out the double tow, particularly since it is likely that all of them carried a spare tow wire which could have been installed on a work drum. Did no-one realise this?

But, as is often the case, much of the process including the risk assessment was developed to validate what was in fact a flawed process, and let’s face it the whole job was based on doing things as cheaply as possible, and once every person with the appropriate levels of expertise had gone there was nothing to stop the disaster taking place.

THE SHIPS INVOLVED (from www.shipsandoil.com)

TYPE: VS 476

NAME: Maersk Chancellor

PHOTO: George Craigen

Length OA 76.4 m Engines 4 x B&W Alpha Workdrum pull 300t
Breadth 17.61 m BHP 14400 Capacity 1 1200m x 74mm
DWT 2440 t kW 10600 Capacity 2  
Deck area 633 m2 For'd Thruster 2 x 1200 bhp Towdrum pull 350t
Fuel 1398 m3 Az Thruster   Capacity 1 1400m x 64mm
Pot water 508 m3 Aft Thrusters 1 x 1200 bhp Capacity 2 1400m x 64mm
Mud 618 m3 Bollard pull 160 tonnes Sharks Jaw  
Base oil 213 m3 DP   Cranes  
Brine 619 m3 Joystick Robertson Tank Cleaning None
Dry bulk 284m3 Year built 1986 Shipyard Orskov
Former Names Kingshav, Oil Chancellor
Comments These vessels were all built at Orskov and spent some time bareboated to OIL, but at the end of the contract period they were purchased by Maersk.


TYPE: ME 909

NAME: Maersk Battler

PHOTO: Joshua Stack

Length OA 84.6 m Engines MAK Workdrum pull 500 tonnes
Breadth 18.8 m BHP 20,200 Capacity 1 2610m x 88mm
DWT 4030 tonnes kW - Capacity 2 2610m x 88mm
Deck area 660 m2 For'd Thruster 1 x 1200 bhp Towdrum pull  
Fuel 840 m3 Az Thruster 1 x 1200 bhp Capacity 1 5850m x 84mm
Pot water 735 m3 Aft Thrusters 2 x 800 bhp Capacity 2  
Mud 600 m3 Bollard pull 230 tonnes Sharks Jaw  
Base oil 230 m3 DP Simrad  Cranes  
Brine 480 m3 Joystick Kamewa Tank Cleaning None
Dry bulk 312 m3 Year built 1997 Shipyard Simek
Former Names  



NAME: Maersk Shipper

PHOTO: Andrew Woodrow




Length OA 82 m Engines  4 x MAK 8M32 Workdrum pull 350 tonnes
Breadth 15.5 m BHP 18250 Capacity 1 4000 m x 77mm
DWT 3490 tonnes kW 13420 Capacity 2 4000m x 77mm
Deck area  620 m2 For'd Thruster 1 x 1200 bhp  Towdrum pull  
Fuel 1577 m3 Az Thruster 1 x 1200 bhp Capacity 1 2500m x 77mm
Pot water 748 m3 Aft Thrusters 1 x 1200 bhp Capacity 2  
Mud 496 m3 Bollard pull 210 t Sharks Jaw Triplex
Base oil   DPII Kongsberg SDPII Cranes 2
Brine   Joystick   Tank Cleaning  
Dry bulk 496 m3 Year Built 1999 Shipyard Singmarine 
Former Names -


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