| Heat Number - 1 | |||||
| Lane | Comp.No. | Name | YoB | Club | Time |
| 1 | 1 | Ho Wai TANG | 13 | S Bournem'th | 1:54.04 |
| 2 | 2 | Jake STOCKDALE | 12 | Poole | 1:44.41 |
| 3 | 3 | Frank OTTON | 11 | Weymouth | 1:34.68 |
| 4 | 4 | Connor PITTWOOD | 10 | Poole | 1:24.08 |
| 5 | 5 | Finlay GILBERT | 09 | Poole | 1:19.42 |
| Heat Number - 2 | |||||
| Lane | Comp.No. | Name | YoB | Club | Time |
| 1 | 7 | Toby BEALE | 09 | N Dorset SC | 1:17.89 |
| 2 | 9 | Sam GRAHAM | 09 | Weymouth | 1:13.53 |
| 3 | 11 | Matthew PROWSE | 08 | West Dorset | 1:11.94 |
| 4 | 10 | Ethan HANGER | 07 | Weymouth | 1:12.75 |
| 5 | 8 | Daniel HUSSEY | 07 | Bridport Bar | 1:13.63 |
| 6 | 6 | Geoffrey GOODRICK | 09 | Weymouth | 1:18.23 |