Heli-cal : Single engine, no floats, over water, line attached!
10/10 for observation. Maybe...
ENGINE: So - let's assume it had 2 engines and did the same thing at the same height and an engine went...... are you any happier ?
FLOATS
I suppose they might cushion the impact as the helicopter goes straight down on to the boat. Floats are, of course, immensely useful in fast flowing water over a dam.
LINE
We now know it is held by hand and will cause no problem if let go.