Gun deck
Deck of a ship used to carry cannons

The term gun deck used to refer to a deck aboard a ship that was primarily used for the mounting of cannon to be fired in broadsides. The term is generally applied to decks enclosed under a roof; smaller and unrated vessels carried their guns on the upper deck, forecastle and quarterdeck, and these were not described as gun decks.
01Slang
The term "gun decking" is also naval slang for fabricating or falsifying something. A possible explanation relates to midshipmen retiring to the gun deck to complete their celestial navigation assignments of computing the ship's position three times daily following morning star sights, noon sun line, and evening star sights. While some midshipmen might be conscientious about computing positions from new observations, others were reputed to extrapolate and back calculate observation data from dead reckoning courses and speeds since earlier observations, and the computations performed on the gun deck were suspect.
This term is now used to indicate the falsification of documentation in order to avoid doing the work or make present conditions seem otherwise acceptable.

Sources and credits
This article is adapted from the Wikipedia article “Gun deck”, written by its contributors and licensed under CC BY-SA 4.0. Fathomly has changed the layout, removed citation markers, navigation and maintenance notices, and adjusted punctuation. This adapted version is shared under the same license. For references, see the original article.
Images, from Wikimedia Commons:
- Batterie inférieure - Victory.jpg by No machine-readable author provided. Achéron assumed (based on copyright claims)., Public domain
- Vasa-lower gun deck-2.jpg by Peter Isotalo, CC BY-SA 3.0
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