It seems like something else is going on besides fatigue.
No way those ships can get close to a Navy vessel without the vessel knowing.
I think the point is the Navy vessel knew (its electronics) but those that were supposed to know how to read them were either crashed on their feet or did not know how to read them due to very poor training. Example: new skippers no longer are sent to boat driving school at Newport but report directly to their boat without any training ... its all OJT.
The something else is the work sched reported in the story as 108 hour wk. Boat driving in the dead of a dark night is very monotonous - we use to have a key we had to turn every 15 minutes or a very load alarm would sound; it is easy to fall asleep.
It’s not that they didn’t detect the ships before the collisions. It’s that the evasive maneuvers were inappropriate to the situation and in the first instance increased the likelihood of collision. The watch is was inadequately manned and the bridge crew, was inefficient at their jobs.
I wish folks would get that point through their heads before they talk about jamming, spoofing, and chinese malware in navigation software. The OOD can see the damn things at least 10-12 miles away and a night you can see the lights on top of the masts of a freigher out to well more than 20 nm. These ships were not surprised. They just had incompent OODs who did not know how to give the orders to set the course and speed to avoid a collision.
Fatigue?, more likely "tired and emotional".