During World War II, Navy sailors slept in “racks”, berthing spaces on their ship, 3ft x 6ft cots/bunks stacked 3 high. The space between the mat and the roof above your head for the bottom and middle bunk was approx. 30″. Some sailors would string up hammocks to sleep on in the ship. When it was too hot they would sleep on the deck of the ship.
And it was always too hot!