Hi DDW,
Perhaps you missed this video posted above, it picks up the action a bit earlier than the first video... Before the guys start looking off to port, at about 1:25 in, Nicholson calls out "We're going over some shoals right now... 40 meters deep..." It was only AFTER that, when the guys start peering out into the darkness to port, trying to figure out what it is they're sensing, or hearing...
https://www.youtube.com/watch?v=MM3Q4SFrMI0#t=125
best regards,
Jon