| Heat Number - 1 | |||||
| Lane | Comp.No. | Name | YoB | Club | Time |
| 2 | 1 | Ezra DOWDS | 15 | Seagulls SC | 1:40.60 |
| 3 | 3 | Miron WOZNIAK | 09 | Blandford | 1:31.61 |
| 4 | 2 | Joseph SUTTON | 11 | Wareham | 1:38.58 |
| Heat Number - 2 | |||||
| Lane | Comp.No. | Name | YoB | Club | Time |
| 1 | 5 | Harry KEEPING | 12 | Bridport Bar | 1:24.31 |
| 2 | 7 | Freddie BROKENSHIRE | 11 | Weymouth | 1:13.88 |
| 3 | 9 | Geoffrey GOODRICK | 09 | Weymouth | 1:09.93 |
| 4 | 8 | Leo IBBOTSON | 10 | Wareham | 1:12.41 |
| 5 | 6 | Jenson LOWE | 12 | Poole | 1:22.36 |
| 6 | 4 | Elliot DOWDS | 12 | Seagulls SC | 1:24.90 |