| U-Boys | 77 | 1104089 | 144144 | U Boys Inc Llc | B2 |
| U.N.E. | 20 | MS8389KA | 158230 | Morgan, Ben | IN |
| Ugly Blu | 17 | MS8733AN | 166644 | Mccutcheon, Kevin D. | RR |
| Ugly Duck | 49 | 985630 | 153451 | Lakeman, Frederick W. | B1 |
| Uluru | 22 | MS3026DB | 166421 | Whitney, George E. | RR |
| Uncertainty | 17 | MS6046KN | 108920 | Mccauley, Joseph H. | B1 |
| Uncle Hungry | 19 | MS9572KB | 141500 | Young, Paul G. | B1 |
| Uncle Johnny | 20 | MS2278AX | 164078 | Amaral, Peter M. | B1 |
| Under Wing | 46 | 1207861 | 3806 | Krzyzewski, Peter M. | CL |
| Unicorn | 72 | 509574 | 115 | Mayhew, Gregory | CL |
| Unicorn | 40 | 626072 | 3124 | Eldridge Jr., Robert J. | ON |
| Unicorn | 42 | MS4283AG | 593 | Tower, Richard E. | CL |
| United States | 76 | 618882 | 73816 | Boat United States, Inc | OL |
| Unity | 20 | MS6530AZ | 164348 | Ryan, James F. | RR |
| Unknown | 24 | MS1868KH | 97803 | Kearns, James L. | B1 |
| Unknown(Fitzgerlad) | 18 | MS5897AY | 162926 | Fitzgerald Iv, John J. | SS |
| Unmarried Man | 21 | MS7042AR | 80575 | White, Steven C. | B1 |
| Uptown Girl | 34 | 982983 | 870 | Pickard, Donna L. | CL |
| Uptown Girl | 34 | 982983 | 92744 | Pickard, Stephen D. | CL |