We are frequently asked what the hull designation letters DD and FF stand for and whether they are abbreviations.
Some believe, incorrectly, that FF stands for Fast Frigate. It does not. Compared to destroyers, while fast enough to do their assigned tasks, frigates are not fast. The designations are simply because the navy uses a minimum of two letters to designate a ship type.
For example, battleships are BB and auxiliaries such as fleet oilers and ammunition ships are AO and AE, respectively. When both tasks are combined into one vessel it is an AOE. Nuclear-powered vessels will have the designator “N” as the final letter.
To aid in identifying the types here is a partial list that includes the more common ship types:
| Hull Designation | Description |
| BB | Battleship |
| CV, CVA, CVN | Aircraft Carrier |
| CVE | Escort Carrier (sometimes called jeep carriers) |
| CA | Heavy Cruiser |
| CL | Light Cruiser |
| CG | Guided Missile Cruiser |
| DD, DDE, DDK, DDR | Destroyer |
| DDG | Guided Missile Destroyer |
| DL | Destroyer Leader |
| DLG | Guided Missile Destroyer Leader |
| DE, DER | Destroyer Escort |
| DEG | Guided Missile Destroyer Escort |
| EDD | Experimental Destroyer |
| FF | Frigate |
| FFG | Guided Missile Frigate |
| LCS | Littoral Combat Ship |
| SS, SSN, SSBN, SSGN | Submarines (B=Ballistic Missile) |
There are many types of Landing Craft, Patrol Vessels, and Auxiliaries.
Amphibious and Landing Vessels
| Hull Designation | Description |
| AGC/LCC | Amphibious Force Command Ship |
| AKA/LKA | Amphibious Cargo Ship |
| APA/LPA | Amphibious Transport |
| APD | High Speed Transport |
| LPR | Amphibious Transport, Small |
| AFS/LFR | Inshore Fire Support Ship |
| LCG(L) | Landing Craft Guns (Large) |
| LCI | Landing Craft Infantry |
| LCS(L)(3) | Landing Craft Support (Large) (Mark 3) |
| LSSL | Landing Craft Support, Large |
| LCT | Landing Craft Tank |
| LCU | Landing Craft Utility |
| LHA | Amphibious Assault Ship (General Purpose) |
| LHD | Amphibious Assault Ship (Multi Purpose) |
| LPD | Amphibious Transport Duck |
| LPH | Amphibious Assault Ship (Helicopter) |
| LSD | Landing Ship Dock |
| LSM | Landing Ship Medium |
| LSM(R) | Landing Ship Medium (Rocket) |
| LST | Landing Ship Tank |
| LSV | Landing Ship Vehicle |
Auxiliary and Service Vessels
| Hull Designation | Description |
| AD | Destroyer Tender |
| AR | Repair Ship |
| ARB | Battle Damage Repair Ship |
| ARC | Cable Repairing/Laying Ship |
| ARG | Repair Ship Internal Combustion Engine |
| ARH | Repair Ship Heavy-hull |
| ARL | Repair Ship Landing Craft |
| ARSD | Salvage Lifting Vessel |
| ARST | Salvage Craft Tender |
| ARV | Repair Ship Aircraft |
| ARVH | Repair Ship Aircraft, Helicopter |
| AS | Submarine Tender |
| ACS | Crane Ship |
| AK | Cargo Ship |
| AKD | Cargo Ship Dock |
| AKL | Cargo Ship Light |
| AKN | Cargo Ship Net |
| AKR | Cargo Ship Vehicle |
| AKS | General Stores Issue Ship |
| AKV | Aircraft Transport |
| AG | Miscellaneous Auxiliary |
| AGB | Icebreaker |
| AGDS | Deep Submergence Support Ship |
| AGEH | Hydrofoil Research Ship |
| AGER | Environmental Research Ship |
| AGF | Command Ship |
| AGM | Missile Range Instrumentation Ship |
| AGMR | Major Communications Relay Ship |
| AGOR | Oceanographic Research Ship |
| AGOS | Ocean Surveillance Ship |
| AGP | Motor Torpedo Boat Tender |
| AGR (YAGR) | Radar Picket Ship |
| AGS | Survey Ship |
| AGSC | Coastal Surveying Ship |
| AGTR | Technical Research Ship |
| AE | Ammunition Ship |
| AF | Stores Ship |
| AFS | Combat Stores Ship |
| T-AKE | Dry Cargo/Ammunition Ship |
| AO | Fleet Oiler / Underway Replenishment Oiler |
| AOE | Fast Combat Support Ship |
| AOG | Gasoline Tanker |
| AOR | Replenishment Fleet Tanker |
| AP | Transport |
| APB | Self-propelled Barracks Ship |
| APC | Coastal Transport |
| APH | Evacuation Transport |
| APM | Mechanized Artillery Transport |
| APV | Transport and Aircraft Ferry |
| ARS | Rescue and Salvage Ship |
| ASR | Submarine Rescue Vessel |
| AT | Fleet Tug |
| ATA | Auxiliary Fleet Tug |
| ATF | Fleet Ocean Tug |
| ATO | Fleet Tug (Old) |
| ATR | Rescue Ocean Tug |
| ATS | Salvage and Rescue Ship |
| AV | Seaplane Tender |
| AVB | Advance Aviation Base Ship |
| AVD | Seaplane Tender, Destroyer |
| AVM | Guided Missile Ship |
| AVP | Small Seaplane Tender |
| AVS | Aviation Stores Issue Ship |
| AVT | Auxiliary Aircraft Landing Training Ship |
| AZ | Lighter-than-Air Aircraft Tender |
| AB | Crane Ship |
| AC | Collier |
| ADG | Degaussing Ship |
| AH | Hospital Ship |
| AN | Net Laying Ship |
| AOT | Oil Transporter |
| AW | Distilling Ship |
| HSV | High Speed Vessel (HSV) |
| IX | Miscellaneous Unclassified (USS CONSTITUTION is an example) |
Mine Warfare Vessels
| Hull Designation | Description |
| ACM | Auxiliary Minelayer |
| AM | Minesweeper |
| AMc | Coastal Minesweeper |
| AMCU | Coastal Minesweeper (Underwater Locator) |
| AMS | Motor Minesweeper |
| BYMS | British Motor Minesweeper |
| CM | Minelayer |
| CMc | Coastal Minelayer |
| DM | Light Minelayer |
| DMS | Highspeed/Destroyer Minesweeper |
| MCM | Mine Countermeasures Ship |
| MCS | Mine Countermeasures Support Ship |
| MHC | Coastal Minehunter |
| MMC | Coastal Minelayer |
| MMD | Fast Minesweeper |
| MMF | Fleet Minelayer |
| MSC | Coastal Minesweeper |
| MSC(O) | Coastal Minesweeper (Old) |
| MSF | Fleet Minesweeper |
| MSI | Inshore Minesweeper |
| MSO | Ocean Minesweeper |
| MSS | Minesweeper (Special Device) |
| SM | Minelaying Submarine |
| YMS | Auxiliary Motor Minesweeper |
Patrol Craft
| Hull Designation | Description |
| PC | Patrol Craft Coastal |
| PC | Submarine Chaser (173′) |
| PCE | Patrol Craft Escort |
| PCER | Patrol Craft Rescue Escort |
| PCH | Submarine Chaser (Hydrofoil) |
| PCS | Patrol Craft Sweeper |
| PE | Eagle Class Patrol Vessel |
| PF | Patrol Frigate |
| PG | Gunboat |
| PGH | Gunboat (Hydrofoil) |
| PGM | Motor Gunboat |
| PHM | Patrol Combatant-Missile (Hydrofoil) |
| PR | River Gunboat |
| PT | Motor Torpedo Boat |
| PTC | Motor Boat Submarine Chasers |
| PY | Patrol Yacht |
| PYc | Coastal Patrol Yacht |
| SC | Submarine Chaser (110′) |