Case notes · Ship operation
The watertight door
Power off does not mean energy-free.
A crew member was maintaining a watertight door on a research vessel. The power supply of the door was switched off, but the hydraulic accumulator still held pressure. When he opened the door and tried to close it again while standing in the frame, he was trapped and died. This case note follows the case as reported and shows where information was lost along the chain.
What happened, step by step
The scene is my own simplified drawing, not a reconstruction of the vessel. It stops before the accident.
- Bulkhead with watertight door
- Power switchboard of the door
- Hydraulic accumulator with pressure gauge
- Control lever with stopper (corridor side)
- Alarm and strobe light
Without lockout/tagout
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Normal state
The door is closed. The stopper sits in the hole of the control lever, as it always did when the door was closed. The accumulator is charged.
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Maintenance with the power off
The crew member opens the cover of the switchboard; its power is off. He checks the hydraulic gauges, the electric motors and other parts, and cleans the inside. The gauge still shows pressure in the accumulator.
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A short break
He leaves the door for a break. The report mentions no lock and no tag on the switchboard or the lever.
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Opening on residual pressure
Back at the door, he takes out the stopper and turns the lever to open. The door opens on the residual pressure in the accumulator. Because the power is off, neither the alarm nor the strobe light signals the movement.
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Closing from inside the frame
Standing in the door frame, he pushes the lever towards closing and tries to insert the stopper at the same time, probably because he regarded it as a safety pin. The residual pressure closes the door. The drawing stops here.
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The chain behind the accident
The investigation found that the crew did not clearly understand the purpose of the stopper. The door was switched off but not free of energy, and it was used as a passage during maintenance.
The same task with lockout/tagout
The principle in four steps, not a complete procedure for a specific vessel.
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Isolate and lock
The person doing the work switches off the switchboard, locks it and attaches a tag.
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Release stored energy
The pressure in the accumulator is released as the manufacturer’s information describes.
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Verify
The gauge shows no pressure, and a test with the lever shows that the door does not move.
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Mark and block
A tag on the lever and a barrier at the door show that the door is under maintenance and is not a passage. Only the person who applied the lock removes it, after the checks before re-energising.
- Previous step
- Next step
- Play
- Pause
- Where the chain breaks
- Step
- Where the chain holds
The stopper: assumed and actual purpose
What the crew assumed
A safety pin that has to be inserted so that the control lever cannot move. When it is in place, the door seems secured.
What it is meant for
The stopper keeps an open door open during inspection or work: it prevents the door from closing if the lever is moved by negligence or malfunction. It does not take the energy out of the door.
The same lever and the same stopper can therefore lead to opposite actions, depending on what people believe they are for. Information about a safety device has to state its purpose and its limits.
The chain: from hazard identification to behaviour on board
My reading of the report along six links. If critical safety information is lost at any of them, a technically functioning safety system can still become dangerous.
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Hazard identification
Watertight doors protect the ship. The door itself is also a source of stored energy and great force, in normal use and during maintenance.
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Manufacturer information
Residual hydraulic pressure after switching off, the missing warning signal without power and the purpose of the stopper have to be stated where people work on the door.
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Operating and maintenance procedures
The procedure has to separate maintenance from using the door as a passage and state how the door is secured while work is in progress.
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Lockout/tagout
Switching off is not isolating. Lock, tag, release of stored energy and verification turn an assumption into a verified state.
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Training and drills
Drills of the door operation have to include the maintenance situation, the stored energy and the stopper, not only normal opening and closing.
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Actual behaviour on board
Under time pressure, people act on what they believe the equipment does. Where the information chain breaks, belief takes the place of knowledge.
Questions for every industry
The same chain applies to interlinked machinery lines, rail vehicles and any other equipment that keeps energy after it has been switched off.
- Which energy remains after switching off, and how is it released?
- How is the energy-free state verified rather than assumed?
- What is a locking device or stopper meant for, and what is it not meant for?
- Who may re-energise, and after which checks?
- When was the maintenance situation last practised, not only normal operation?
My work covers documentation and information design. Procedures, instruction and supervision on board or on site remain with the operator; inspection and conformity remain with the responsible bodies.
Source
MARS Report 202613 of The Nautical Institute, as published by Marine Insight on 17 April 2026 (‘Real Life Incident: Engine Room Crew Member Dies Because Of Watertight Door’) and by SWZ|Maritime on 29 May 2026. I retell the case in my own words; the drawing is my own, simplified and not to scale.