Many novice sailors, confusing the words "binnacle" and barnacle, have wondered what their illnesses had to do with crusty growths found on the hull of a ship. Their confusion is understandable.
A binnacle is a waist-high case or stand on the deck of a ship, generally mounted in front of the helmsman, in which navigational instruments are placed for easy and quick reference as well as to protect the delicate instruments. Its traditional purpose was to hold the ship's magnetic compass, mounted in gimbals to keep it level while the ship pitched and rolled.
The term binnacle list, in lieu of sick list, originated years ago when ship corpsmen used to place a list of sick on the binnacle each morning for the use of the officer of the deck to inform the captain about the crew's health. After long practice, it came to be called binnacle list.
How does this relate to today?
The Morning Report of the Sick, NAVMED 6320/19, is used to excuse an individual from duty for a period of more than 24 hours. This report contains a list of the sick and injured, including names, diagnoses, and conditions. It is prepared by the senior medical department representative on board and is submitted to the commanding officer by 1000 daily.
When it is necessary to excuse someone from duty after the Morning Report of the Sick is submitted, add the patient’s name to the Binnacle List, and submit the appropriate report to the commanding officer. If a patient is still unfit for duty when the next Morning Report of the Sick is submitted, add his name to the NAVMED 6320/19 as of the date on which his name was first entered on the Binnacle List. If a satisfactory diagnosis cannot be established, simply note “Diagnosis undetermined” and indicate the chief complaint. Report suspected cases of malingering to the commanding officer.