One Person Fewer on the Bridge, and the Officer Is Overloaded Seven Times as Often

ABS, the American class society, has published a paper with a simple message for owners: before you automate a ship or cut the crew, test on a computer whether the people who are left can still do the work.

The method is called human performance modelling. In plain words, you build a model of the tasks a person has to do, how long each one takes and how many can be handled at once, and you run a situation through it many times to see where the person runs out of capacity. Aircraft makers, nuclear plants and navies have used it for years. Shipping mostly has not.

The example is the reason to read it. ABS modelled one port approach and ran it 100 times for each crew size. With four people on the bridge, the officer on watch went over the model's overload limit in 8% of runs. With three people, in 61%. The officer's average peak workload score rose from 18.4 to 27.6. Same ship, same port, same equipment. The only change was one person fewer.

Now the honest part, and ABS says it first. These numbers are an illustration. They come from a model, not from a real bridge. A model is only as good as the task list and the timings put into it, and ABS states that modelling cannot replace simulator trials or the judgement of experienced people. Nobody should quote 61% as a fact about ships.

So why lead with it? Because it turns a feeling into a method. Every master knows the approach where one more thing would have been too much. Until now that was an opinion, and opinions lose against a spreadsheet that shows a crew saving. A workload model gives the safety side a number of its own to put on the table.

The paper covers more than manning. It names bridge design, alarm management, emergency procedures and remote operation centres, including the question of how many ships one person ashore can really watch. ABS asks for three things: put this modelling into the safety management system, build shared task lists and scenarios for ships, and agree a common way to check the results.

What to do with it. If a supplier or a yard offers you automation that "allows reduced manning", ask to see the workload study behind that sentence. If there is none, you have learned something. [Digital Ship · ABS · white paper · AiatSea, 27 September]

This story is part of the Maritime AI Digest of 11 October 2026.