Flooding cofferdam during speed log maintenance


The crew attempted to carry out repairs to the speed log unit, which was in the forward cofferdam, while the vessel was underway.

What the reporter told us:

The repair team consisted of the Chief Engineer who was to supervise the job, the 3rd Engineer, and the Electrician, none of whom had carried out this type of repair before. The repair team planned to follow the manufacturer’s troubleshooting instructions.

Upon request, the manufacturers of the speed log had sent instructions to the company’s electrical department, who forwarded them to the ship. Neither the company’s technical department nor the HSQE-marine departments had been notified of this planned non-routine repair job.

The master reported that the job had been discussed at the morning work planning meeting although no specific risk assessment was carried out for this work.

Enclosed space entry procedures were followed, and the necessary entry permits issued. Furthermore, a team was standing by outside the cofferdam to assist the team in carrying out the work.

In addition to the risks associated with entry into a confined space, the additional risks associated with this specific task are flooding, operational delays, and personal injury.

Additional information:

The repair team attempted to inspect the sensor and repair the malfunctioning speed log following the manufacturers troubleshooting instructions.

The work involved removing and inspecting the sensor of the speed log which was in the forward cofferdam. No details are available concerning the size of the cofferdam.

As per the maker’s manual, a series of steps were required to be followed to carry out this job safely and effectively.

  • A chain stopper was required to be fitted to both the sea valve and the sensor. This was necessary to hold the sensor in the sea valve until the valve was confirmed to be fully closed. Only after the sea valve was fully closed should the chain stopper be removed.
  • The required chain stopper was installed by the crew before the commencement of the job as per the maker’s instructions.
  • However, when performing the last step, the crew could not close the handle of the sea valve fully. The crew assumed that the sensor was obstructing the valve and they decided to remove the chain stopper and pulled the sensor out from the sea valve with the valve still not fully closed.
  • As a result, seawater entered the cofferdam from the sea valve when the sensor was removed.
  • The crew attempted to insert the sensor back into the housing, but this was not possible due to the ingress of seawater.
  • With the sensor removed, the sea valve was then closed completely, and the work postponed. The cofferdam was sealed, and control measures established to monitor the condition of the compartment for any further flooding.
  • Eight days later when the vessel was at anchor, divers attended the vessel and sealed the sea chest. At this time, the job was carried out, with the assistance of a service engineer from the manufacturers, by the responsible crew who located the sensor back into position to restore the speed log’s function.

An in-house investigation was carried out which concluded that the incident had occurred due to failure to comply with and implement the company’s basic safety procedures and failure to follow the equipment manufacturer’s instructions.

Direct Causes:

  • Improper implementation of the company’s instructions and procedures.
  • Failure to follow the maker’s safety instructions for the specific job.

Basic Causes:

  • Failure of basic communication within the company offices
  • Inadequate instructions from the company and improper planning of the job. Neither the HSQE-marine nor the technical department’s responsible person were informed about this non-routine and high-risk job.
  • A proper risk assessment was not conducted for the non-routine job.

Lessons Learned (Reporter’s conclusions)

No instructions should be given to vessels in the fleet for non-routine works unless they have been agreed by the technical and HSQE-marine department personnel and a risk assessment has been carried out in cooperation with the vessel.

Every work activity needs adequate & proper planning, detailed hazard identification and a comprehensive risk assessment to determine the necessary control measures to mitigate the likelihood and consequence of an undesired event taking place.

CHIRP comment:

It was the unanimous opinion of the MAB that opening a hull penetration below the waterline while underway and mid-ocean is not a good policy. The following points were also noted.

  • The team on board were too close and engrossed in the small details to step back and see the dangers of the bigger picture.
  • Some on board risk assessments for non-routine or exceptional tasks are too focused on ticking the boxes and completing the form rather than taking the time to identify and make in-depth assessments of individual potential hazards.
  • The technical and HSQE – marine departments had not been informed by the electrical department, who were aware of this non-routine job because they had forwarded the instructions received from the speed log manufacturers to the ship. All technical and HSQE-marine departments in the office must communicate with each other to understand the risks.
  • While there were failures on board the ship, there were also failures of management with the shore technical and HSQE-marine teams being unaware of the planned operation. The office should ask itself what went wrong at their end and promulgate their findings to the fleet.


Report Ends………………………….