[Lou L]

However, I assume there are redundant alarm systems if ships get too close? Should the bells and whistles all have been blaring before the crash on the Fitzgerald and the tanker???

No "alarm systems" per se; the ship had ample sensors to detect surface traffic. The "alarms" were watchstanders on the bridge, lookout stations, and in the Combat Information Center. There had to be a minimum of dozen people--perhaps as high as two dozen--that should've seen the presence of the ACX Crystal.

[Uncle Sam 911]

I guess the senior officer on watch that night will have some splainin to do.