| U-Boys | 77 | 1104089 | 144144 | U Boys Inc Llc | B2 |
| Uckaday | 22 | MS3492AN | 151413 | Miner, Christopher N. | B1 |
| Ugly Duck | 49 | 985630 | 153451 | Lakeman, Frederick W. | B1 |
| Uncertainty | 17 | MS6046KN | 108920 | Mccauley, Joseph H. | B1 |
| Unchained | 24 | MS4147HB | 144515 | Leblanc, Craig M. | B1 |
| Unicorn | 42 | MS4283AG | 593 | Tower, Richard E. | CL |
| Unicorn | 40 | 626072 | 3124 | Eldridge Jr., Robert J. | ON |
| Unicorn | 72 | 509574 | 115 | Mayhew, Gregory | CL |
| United States | 76 | 618882 | 73816 | Boat United States, Inc | OL |
| Unknown | 25 | MS1584KL | 113124 | Martin, Charles D. | B1 |
| Unknown | 38 | MS5623AK | 141808 | Martin, William | OL |
| Unknown | 24 | MS1868KH | 97803 | Kearns, James L. | B1 |
| Uptown Girl | 34 | 982983 | 92744 | Pickard, Stephen D. | CL |
| Uptown Girl | 34 | 982983 | 870 | Pickard, Donna L. | CL |
| Ursa Minor | 19 | MS5351YY | 153756 | Lambrecht, Jessie A. | SL |