Weapons Department: Headed by the Weapons Officer. These are the divisions:
First Division. This is the deck division, the sailors are the Boatswain’s Mates or Bo’sun’s Mates (BM). Regardless of the rank of the division officer, he or she is the First Lieutenant. They run and maintain the boats (boat engines are maintained by A Gang). They operate the anchor and maintain the mooring gear, the main deck areas and the hull above the waterline. The sailors are also known as “Deck Apes.” As a group, they are tied with the BTs for being a rough and tough group. First Division is a throwback to the age of sail. The First Lieutenant is in charge of the ship’s supply of toilet paper; running out of TP is a sure way to make long-term enemies. A smart 1st LT has an off-the-books stash in several places around the ship.
Second Division: They are the Gunner’s Mates, they maintain and operate the ship’s guns, from the small machine guns up to the 16" guns on battleships. They maintain the small arms for use by the ship's defense forces and watchstanders. On ships without a main missile battery, the Firecontrol Men (FC) are in 2nd Division. FCs maintain the gunfire control radars and the fire control plotting equipment down in Gun Plot.
Third Division/ AS Division: This is the sonar division, the sonar technicians, or STGs. (STSs are on submarines.) Whether it is a dinky SQS-56 on a Perry Class FFG, a SQS-38 on a DDG or a huge SQS-26 on a Knox Class FF or a guided missile cruiser, the sonar gear is operated and maintained by STGs. There might be a relative handful of STGs on a DDG or well over 20 on a Knox Class FF with a then state-of-the-art passive sonar suite. The ASW torpedo tubes are maintained by Torpedomen (TMs) who are also in 3rd Division. Back when ASROC launchers were fitted to ships, the launchers were part of 3rd Division, the launcher was operated and maintained by two or three Gunner’s Mate Technicians (GMTs).
Fox Division: You have to be careful with this reference. On a missile shooter, Fox Division is made up of Gunner’s Mates Missile (GMMs), who maintain the launcher, loading gear and the missile magazines. But Fox Division is often a name used on other ships for other uses; I’ve seen the name used by Supply Department and by 3rd Division on non-missile ships. If the ship is a missile shooter, the FCs are in this division.
Supply Department: The officers in the Supply Department, typically the Supply Officer and the Disbursing Officer, are staff corps officers, not line officers. They do not stand underway watches, though some ships make the Disbursing Officer stand in-port watches.
The galley and food service operations are run by Mess Specialists (MSs), assisted by young sailors drafted from every division on the ship for 90-day tours and known as the Mess Cooks or “Mess Cranks.” Being sent for such a tour was known as “cranking.” Supply Department runs the ship’s laundry and the barber shop, those areas are staffed by SHs and I’ve forgotten what the rate designation officially stood for (you can guess what the unofficial term was). Storekeepers (SKs) ran the ship’s store, kept the soda machines stocked and handled the tracking, ordering and inventorying of all supplies and spare parts. The Disbursing Officer and the Disbursing Clerks (DKs) are in charge of the ship’s payroll. It’s a Navy-wide joke that each month, there is a softball game at Leavenworth Military Prison between the disbursing officers and the ensigns who were in charge of classified material.
N/X Division: Until the XO was mandated to also be the ship’s navigator, the Navigator was the division officer of N/X. After the change, the Navigation Officer became the new title for the division officer, and the Navigation Officer’s work underway is closely scrutinized by the XO. On larger ships that have an embarked chaplain and/or a doctor, those officers are part of N/X division. The Navigation Officer personally supervised the navigation plot in restricted waters, such as entering or leaving port. In open-ocean steaming, that duty fell to the Officer of the Deck.
N/X Division is made up of five rates: The Quartermasters (QMs), the Hospitalmen (HM), Personnelmen (PN), Postal Clerks (PKs) and the Yeomen (YM). The Quartermasters keep track of the navigation plot, they maintain the chart library, the Bridge, the Flying Bridge and the Charthouse. The QMs used to shoot morning and evening stars with a sextant and keep a running plot underway with Sun lines. The HMs were always referred to as “corpsmen,” they ran Sick Bay and administered the medical records for the ship. One or two of the corpsmen were rated as “independent duty” corpsmen and were very highly trained. Pissing off a corpsman was a great way to find that one’s shot record had mysteriously disappeared.
Small ships had one PK, larger ones may have two or more. If the ship was deployed and a mail delivery was made, the PK was everyone’s best friend. PNs maintained the enlisted service records and cut orders for transfers and training. They did the papers for sailors going on leave. The YMs handled the administration of the ship, they basically were the office staff for the XO. YMs also maintained the personnel records for the officers.
That’s pretty much everyone on a small warship.