Microlearning · Ship operation
Power off does not mean energy-free
One case, four voices, four questions.
This microlearning builds on the case note “The watertight door.” You get to know the case in a few sentences, read what four people say about it from their role, and check after each voice whether the key information has come across.
- About 8 minutes
- 4 questions with feedback
- No sign-in; answers are not stored
What this is about
A watertight door is switched off for maintenance and can still move. After this microlearning, you can use the scene to:
- recognize the state “switched off but not energy-free,”
- tell the purpose of the stopper from its assumed purpose,
- select the information that belongs where the work is done,
- put the four steps of lockout/tagout in the right order.
Each voice is followed by a question. If your answer is right, you get more depth. If it is wrong, a hint shows where the answer is in the case note, and you get a second attempt; after that, the solution appears with the reasoning.
The four people are fictitious roles, not people involved in the case. They speak about what the report describes; their view is my reading. The accident itself is not shown.
- Back
- Next
- Check answer
- Please choose an answer first.
- Correct.
- The second attempt is not right either. Here is the solution.
- Part
- of
- Move up
- Move down
- Use “Move up” and “Move down” to reorder the steps.
- wrong choice
- correct
- Answered correctly at the first attempt: {n} of {total} questions. Nothing is stored.
- Start again
Case brief
- Bulkhead with watertight door
- Power switchboard of the door (switched off)
- Hydraulic accumulator with pressure gauge (under pressure)
- Control lever with stopper
- Alarm and strobe light (silent without power)
On a research vessel, a crew member is maintaining a watertight door. The door’s switchboard is switched off, but the hydraulic accumulator still holds pressure, and the gauge shows it.
Without power, neither the alarm nor the strobe light signals a movement of the door. After a break, he opens the door with the control lever and tries to close it again while standing in the frame. The residual pressure closes the door, and he is fatally trapped.
The investigation found that the crew did not clearly understand the purpose of the stopper on the control lever.
Based on MARS Report 202613 of The Nautical Institute, as retold in the case note. The drawing is simplified and shows the state during maintenance.
What “switched off” means here
“Switchboard off” sounds like “door safe.” For this door, it is not. The hydraulic accumulator keeps its pressure without power, and the gauge shows it. With that pressure, the control lever can open and close the door. What is switched off is the power supply, not the stored energy.
What the stopper is for
The stopper sat in the hole of the control lever, as it always did when the door was closed. That made it look like a safety pin that locks the lever. It is meant for an open door: during inspection or work, it keeps the door open so that it does not close if the lever is moved by negligence or malfunction.
What belongs at the door
I also write for the person standing at the door during maintenance, not only for normal operation. They need to know that the accumulator holds pressure after switching off, that without power neither the alarm nor the strobe light gives a warning, and what the stopper is meant for. This information belongs where people work on the door.
The report does not reproduce the manufacturer’s information. This voice shows how the case note reads the link “manufacturer information.”
Lockout/tagout in four steps
Drills of the door operation must not stop at opening and closing in normal operation. Maintenance belongs in them, with stored energy, the stopper and the lock. Lockout/tagout turns an assumption into a verified state, but only if the steps happen in the right order.
Applying it to your work
Think of a machine or piece of equipment in your own work that can keep energy after it has been switched off, for example through pressure, spring force, gravity, residual voltage or heat.
Check this equipment with the questions from the case note:
- 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-energize, and after which checks?
- When was the maintenance situation last practiced, not only normal operation?
The key points in three sentences
- Switched off is not energy-free: stored energy remains until it has been released and the state has been verified.
- People use a safety device for what they believe it is for. Information has to state its purpose and its limits.
- Lockout/tagout turns an assumption into a verified state: isolate and lock, release energy, verify, mark.
How this microlearning is built
This microlearning is a work sample in learning and information design. Every decision traces back to a learning outcome.
- One whole, real task. Following Merrill’s First Principles of Instruction, a real case is at the center: the case brief activates prior knowledge, the voices demonstrate, the questions let learners apply, and the transfer connects to their own work.
- Outcomes that can be observed. The outcomes name audience, behavior, condition and degree (ABCD) and sit at the levels understand, analyze and apply of Bloom’s revised taxonomy. Each question checks exactly one outcome.
- Sequence after Gagné. Attention, objectives, prior knowledge, content, guidance, performance, feedback and transfer follow in this order, condensed to eight minutes.
- Feedback in two stages. A hint with the place to look after the first mistake keeps the task in the range where learners can progress with support. The solution after the second mistake keeps a misunderstanding from standing.
- Words and pictures belong together. Following Mayer’s principles, each voice sits right next to its portrait and right before its question, and the drawing shows only what the case needs. The portraits are drawn so that nobody mistakes them for people involved.
- Usable for everyone. Keyboard operation, visible progress, feedback never by color alone, reduced motion and a readable version without JavaScript follow the principles of Universal Design for Learning.
This microlearning does not replace instruction. Procedures, instruction and supervision on board remain with the operator.
Source
MARS Report 202613 of The Nautical Institute, as published by Marine Insight on April 17, 2026, and by SWZ|Maritime on May 29, 2026, retold in the case note “The watertight door.” Roles, quotes and drawings are my own.