Life vests will not prevent someone in the water and close to an active propeller from being sucked under and into the props. Navy ships at speed and merchant container ships have huge wakes and so the suction is huge.
Several times saw surfaced boomer subs going slow returning in Strait of Juan de Fuca - wakes were about 4 feet high and 30 across near the boat.
What a shame. Maybe it is R.I.P. for the missing sailors who couldn’t even swim away. Something about how the two boats hit one another maybe — danger zones close to point of collision.