I know nothing about the military or naval practices but this sounds hard and very costly... you want someone on shift 24/7 with his head constantly rotating watching out in all directions? Or maybe 3-4 people simultaneously looking out each in a single direction? That would mean you have a bunch of people doing literally nothing productive (besides watching) at any given point in time, some of them even being asleep since you want 24/7 shifts... and they have to not get bored or look away for any nontrivial period of time. It seems very difficult.
They are not doing "nothing productive", they are keeping watch to prevent exactly this type of accident from happening.
Do you really think that the entire ship goes to to sleep at night on a 2 billion dollar naval destroyer while it cruises in a crowded shipping lane? Even the $250M office/residential building where I work has 2 night watchmen and a building engineer or two on duty at all times... and the building is unlikely to have a collision when another building moves into its path.
I didn't say they all go to sleep, they probably have lots of things to do at various times. And I wasn't talking about more-sensitive points like crowded shipping lanes. I was just talking about having people on duty to literally keep a watch out over the sea the entire time. Not sure why you twist my words like that.
Or you're saying they do have watchmen 24/7 but their watchmen are just blind? How did they manage to collide 4 times this year if they had people watching the sea the whole time?
Oh, and don't forget others are suggesting sleep deprivation as the cause. Which is not exactly inconsistent with my point that keeping watch is probably difficult and costly...
Every vessel must at all times keep a proper look-out
by sight (day shape or lights by eyes or visual aids),
hearing (sound signal or Marine VHF radio)
and all available means (e.g. Radar, ARPA, AIS, GMDSS...)
in order to judge if risk of collision exists
So WTF was that destroyer doing for 10-20 minutes minimum that had it in a collision with another ship?