For the damage to be on the port quarter the McCain must have been travelling south-east, given the Alnic was heading south-west (AIS tracking video). However she was due to berth in Singapore that day and the termination/entrance of a TSS is not the place to be stooging around changing course. As well, if it was a crossing situation I would have expected the damage to have been more significant.
Here is one possibility... the Alnic was the overtaking vessel, the McCain having reduced speed to arrive at PBG at pre-determined time.
If the US naval vessel wasn't crossing the TSS but was ahead of the Alnic then the following video shows what is imo likely to have happened. Note in the following video the water being displaced by the overtaking vessel creates a high pressure zone near the bow and pushes the smaller vessels stern to stbd and across the bows of the overtaking vessel.
Naval vessels don't comply with nav regs for positioning of lights or are required to have AIS active which may have contributed to failure to keep a proper and effective lookout onboard the Alnic, that is they relied on AIS tags on the radar to identify nearby vessels.
The period between nautical and civil twilight is a difficult time to spot a grey hulled ship low in the water, the lookout may even have been on the helm given the location.
If this is the scenario then the McCain would have been the stand-on vessel, required to maintain course and speed until collision was unavoidable then she would have been required to take action. If the McCain had been keeping a proper lookout then she could have taken avoiding action as soon as it became apparent to her that the Alnic was not taking sufficeint action to avoid collision . Unfortunately, as in the video above this may have been left too late and had become impossible.
Note, in almost all cases both vessels are held responsible for a collision, blame is apportioned appropriately on the given circumstances.
