The Navy Department Library
Standard Nomemclature for Naval Vessels: General Order No. 541, 17 July 1920
Navy Department,
Office of Naval Operations,
Washington, D. C., July 17, 1920
STANDARD NOMENCLATURE FOR NAVAL VESSELS
1. In order to provide a standard nomenclature for types and classes of vessels comprised in the United States Navy, as well as a standard system of identification numbers which may be used, where pertinent, in correspondence and for the marking of spare parts and the like, there will be published annually a Ships’ Data Book, prepared by the Bureau of Construction and Repair and approved by the Secretary of the Navy, which will contain the standard nomenclature, identification numbers, and abbreviations shall be used in official correspondence and communications and for the marking of spare parts.
2. In advance of the issue of the next Ships’ Data Book, which will contain the approved standard designations, including identification numbers of all naval vessels, the following detailed list shows the names of types, type designations, names of classes, and class designations to be included in future editions:
| Type | Type designation | Class | Class designation |
| Battleship | B | Battleship, first line Battleship, second line Monitor, first line Monitor, second line |
BB OBB BM OBM |
| Cruiser | C | Battle cruiser, first line Battle cruise, second line Cruiser, first line Cruiser, second line Light cruiser, first line Light cruiser, second line Aircraft carrier, first line Aircraft carrier, second line Mine layer, first line Mine layer, second line |
CC OCC CA OCA CL OCL CV OCV CM OCM |
| Destroyer | D | Destroyer, first line Destroyer, second line Destroyer leader Light mine layer |
DD ODD DL DM |
| Submarine | S | Submarine, first line Submarine, second line Fleet submarine, first line Fleet submarine, second line Cruiser submarine Minelaying submarine |
SS OSS SF OSF SC SM |
| Patrol vessel | P | Eagle Submarine chaser Gunboat Yacht |
PE PC PG PY |
| Auxiliary | A | Destroyer tender Submarine tender Lighter-than-aircraft tender Heavier-than-aircraft tender Repair ship Storeship Collier Oiler Ammunition ship Cargo ship Transport Hospital ship Fleet tug Mine sweeper Auxiliaries, miscellaneous |
AD AS AZ AV AR AF AC AO AE AK AP AH AT AM AG |
| Lighter-than-aircraft | Z | Rigid dirigible Nonrigid dirigible Kite balloon |
ZR ZN AK |
| Heavier-than-aircraft | V | Fighting plane Observation plane Scouting plane Patrol plane Torpedo and bombing plane Fleet plane |
VF VO VS VP VT VG |
| District craft | Y | Ash lighter Ambulance boat Ammunition lighter Coal barge Car float Fueling barge Floating derrick Dredge Freight lighter Garbage lighter Heating scow Mud scow Oil barge Ferry boat and launch Pile driver Stevedoring barge Torpedo testing barge Water barge Floating worlkshop Seaplane barge District tug District patrol |
YA YH YE YC YCF YCD YD YM YF YG YHT YMD YO YFB YPD YS YTT YW YR YV YT YP |
Note: Vessels taken over temporarily by the Navy will have designating letters and numbers assigned according to the type and class to which they belong. The identification numbers for such vessels will always be preceded by the letter “X,” indicating the temporary nature of the assignment; for example, if there were already four heavier-than-aircraft tenders in the Navy, and a fifth were taken in temporarily, it would be given an identification number XAV5. The number “5” should not be used again for vessels of this class; the next heavier-than-aircraft tender built or taken over would be “6.”
R.E. Coontz
Acting Secretary of the Navy
