Why are Carriers designated CV not C Destroyers designated DD not just D and why are submarines designated SS not just S?

Answer 1

The reason that Destroyers are not just classified with a single "D" and Submarines with just an "S" is that there are different classes of each. It is the hull designation that denotes the vessel's function, and with the advent of the Nuclear Navy, its propulsion type as well.

The hull designator denotes the hull type, shipyard hull number, its purpose, and its propulsion mode. For example SSN stands for "Submersible Ship, Nuclear"; SSBN is Submersible Ship, Ballistic, Nuclear; and SSGN is Submersible Ship, Guided Missile, Nuclear. Any vessel that isn't a variant (rare in today's Navy) has a single designation - BB, DD, etc. Nuclear powered vessels are denoted with an "N" in the designation.

Another example is my old boat, USS RAY (SSN-653). Her designation was Submersible Ship, Nuclear, hull number 653 in Navy technical parlance.

B is a pre-1920's Battleship; BB is a post-1920's Battleship, and a BBG is a Guided Missile Battleship. A DD is a regular line Destroyer; a DE was a Destroyer Escort. A DDG, such as the Arleigh Burke class Destroyers, are Guided Missile Destroyers.

SS doesn't stand for Submarine - it stands for "Submersible Ship". This goes back to the earliest days of Submarines, when they weren't true submersibles like they are today. Until teardrop and cigar shaped hulls were designed, and longer range propulsion methods made crew limitations the only liability, older submarines were essentially surface vessels that had a limited submerged operational capability. They were, literally, "Submersible Ships". What makes them different than today's boats is that the old design made them much faster on the surface than the ever were submerged. Today's submarines are true submersibles by all definitions, much faster submerged than when surfaced. Even modern Diesel Electric boats can remain submerged for many days at a time without the need for a battery charge.

For example, my former Rate/Rank/Warfare Designator, if fully written out, would be shown as "Sonar Technician (Submarines) or STS, First Class (STS1), SS - or Submersible Ships. Written out, my Rate / Rank was STS1(SS).

For submarine hull types, there are currently 3 in the U.S. inventory - SSN, SSGN, and SSBN. SSN's are Nuclear Fast-Attack Submarines - Sturgeon, L.A., Seawolf and Virginia Classes. SSBN's are Ballistic Missile Submarines (Ohio class, etc.) SSGN's are converted older SSBN's that have had their Ballistic Missiles removed as part of the Treaty with the former Soviet Union. They were converted to Cruise Missile launch platforms.

During the Korean War, many former WW2 Fleet Boats were converted for Radar Picket duty along the Korean coastline. Their designations were "SSR", or "Submersible Ship, Radar Picket"

Other ships have similar hull designations. Aircraft Carriers, for example carry the primary hull designator "CV", for Carrier Vessel, "CVA" for Carrier Vessel, Attack (large conventional powered AC's), and "CVN", for "Carrier Vessel, Nuclear".