| Heat Number - 1 | |||||
| Lane | Comp.No. | Name | YoB | Club | Time |
| 2 | 1 | Luan ISUFI | 15 | Poole | 3:37.90 |
| 3 | 3 | Joseph RUDD | 13 | Weymouth | 3:18.72 |
| 4 | 2 | Ralph VEARNCOMBE | 14 | Poole | 3:22.75 |
| Heat Number - 2 | |||||
| Lane | Comp.No. | Name | YoB | Club | Time |
| 1 | 4 | Max PALMER | 14 | S Bournem'th | 3:12.37 |
| 2 | 6 | Leo IBBOTSON | 10 | Wareham | 2:43.86 |
| 3 | 8 | Oliver BUCK | 11 | N Dorset SC | 2:36.34 |
| 4 | 7 | Geoffrey GOODRICK | 09 | Weymouth | 2:38.41 |
| 5 | 5 | Oscar MACHTYLSKI | 15 | Poole | 3:08.64 |