> Self-righting mechanisms
Modern ships can easily transfer ballast fluids (typically sea water, but sometimes fuel or distilate water) to correct any listing. There are no methods of righting an overturned ship because that would require an astronomical amount of moment.
> Self-sealing compartmental design
Watertight doors can be controlled from multiple stations on the ship, such as the bridge or the engineering control room.
> Re-floating devices
If you mean safety devices: Ships carry liferafts that, in the event of sinking, automatically detach from the ship, float to the surface, and inflate. If you mean re-floating the entire ship: Not feasible to re-float something that weighs hundreds of thousands of tons just to save some scrap steel.
> "Carefree" fly-by-wire preventing dangerous manoeuvering
Ships have automatic navigation and piloting, though not in shallower waters such as in ports.
For example:
* How good are the systems that realise that ships need righting and transfer the ballast automatically before it overturns?
* Refloating may not be feasible once the ship is overturned, but by then it'll be too late. How about self-inflating bags that inflate as the ship starts to sink, buying valuable time for people to escape?
* Automatic navigation is one thing, but how can we improve it? Does it identify foreign objects above/below the waterline? Does it have stabilisation assistance? Does it pump ballast around to ensure the best possible handling under any condition?
Just because these things already exist doesn't mean they can't be improved. In some cases this could potentially be done relatively cheaply.
Note that this caused the crash Air France Flight 447 because it trained the pilot to react incorrectly (too aggressively) in an emergency.
Examples include:
-Self-righting mechanisms
-Self-sealing compartmental design
-Re-floating devices
-"Carefree" fly-by-wire preventing dangerous manoeuvering