| Y |
| Yankee Station | Carrier Force Area off Coast of Vietnam. |
| YC | Open Lighter |
| YD | Floating Crane |
| YFNB | Large Covered Lighter (Repair Barge) |
| YFR | Refrigerated Covered Lighter |
| YFU | Harbor Utility Craft |
| YG | Garbage Lighter |
| YLLC | Salvage Lift Graft, Light |
| Yo-Yo - High speed | An offensive tactic in which the attacker maneuvers through both vertical and horizontal planes to prevent an overshoot in the plane of the defender's turn. |
| Yo-Yo - Low speed | A dive for airspeed and a pull up for position closure. |
| YOG | Yard Oiler |
| YON | Fuel Oil Barge |
| YR | Floating Workshop |
| YR | Harbor Repair Craft |
| YR | Repair Barge |
| YRBM | Submarine Repair, Berthing, and Messing Barge |
| YTB | Large Harbor Tugs |
| YTL | Small Harbor Tug |
| YTM | Medium Harbor Tug |
| YW | Barge Water |
| YWN | Water Barge |