Maintenance is staggered because there is only so much room for people to work in inside the engine room.
For most ships, it would be cheaper for the company to pay for the crew than lose out on shipping contracts due to being in port for maintenance.
Engineers can detect a lot of problems that machines can't, be it unusual smells, sounds, vibrations, temperatures, etc. Sure there are probes that can detect vibrations and temperatures, but they would have to be placed everywhere (not just the hundred or so usual spots), and then they have to be programmed. I use a handheld device to measure vibrations on running machinery. It's only as good as it's programming, and it's not that good.
Additionally, hoses burst, o-rings leak, filters need changing, etc. We don't have machines today that can fix those problems on the fly.
My last ship I was on was Diesel Electric. It was incredibly automated, yet still we had MAJOR problems because some circuit boards died.
There seemed a clear point of marginal utility in automation.
Lots of these things could be happening on airplanes but generally don't. Why can't we get airplane-level reliability on ships?
That's why there's someone always on watch in the engine room.
Adding an automated backup to every system would be a considerable cost, and even then a manual option would be required and some-times relied upon.
(Former ship engineer.)
http://www.youtube.com/watch?v=Ek8GKqmJ7n0#t=70
the annoying thing with these robots is that you still have to specialize the hands,grippers, and tools for the task or group of tasks. We don't really have great "really general purpose" robotic manipulators, but we can make really good specialized robots for very well defined tasks, so I don't think the shipping industry is going to pay for an array of expensive special purpose robots. The technology is really not here yet, but getting ever closer, it's the holy grail of robotics and control systems research. Sorry for the ramble.
No ramble at all I found it useful, thanks for sharing it!
Imagine a car which would monitor each of its parts, diagnose an issue on the gearbox, and turn it offline while driving to replace it.