Your dad probably mentioned more than just the violent pitching. I’ve heard guys tell of the ships creaking and groaning giving them nightmares.
In the mornings, all the troops were ordered up on deck and were secured with ropes to the structure of the ship. Sailors had to go through the lower decks where the troops had slept to firehose out all the vomit. A couple of times the ship listed to the point where the soldiers took a dunk in the North Atlantic.