Frigate going from full ahead to emergency stop - GIF

[hemmjo]

Yep, as mentioned above. it would be very difficult to change direction of that propeller shaft at speed. The water forcing that prop to keep turning one direction while trying to "shift gears". Just like a truck going down hill if you don't get it downshifted before you get going too fast, you are NOT going to be able to do it at all.

Curious what that looked like from the side with some perspective for the speed change.