Hot racking

[1] The practice dates back at least to the sixteenth century, and today is particularly applied aboard submarines, where maximization of space is especially important.

Generally, the lowest ranking members of the crew are required to hot rack.

Hot racking is sometimes used in jails and prisons to deal with overcrowding.

[citation needed] Depending upon the watch system, two, or even three people may end up sharing the same bunk.

The rack is therefore said to be "hot", that is, still warm from the vacating crew member's body heat.