A solid batting performance from the Navy was derailed by a collapse in the middle order, but the RAF could not take advantage.
The closing minutes of the game saw the Air Force needing a maximum from the final ball which they couldn't provide.
The Navy's opening partnership provided their top scorers, with Leo Buscombe (25) and Jonathan Parker (22) leading the way.
However, two wickets each for Kieran Pearce, Tom Shorthouse and Ash Watson meant the RAF limited the Senior Service to 114-8.
It was a target the RAF felt they could reach, but a fantastic fielding performance from the Navy stopped their momentum.
Adam Fisher was the top scorer with 42 runs, but disappointing totals from Shorthouse (4), Sam Beals (0) and Sam Bloor (13) meant a score of 110/6 and win for the Navy.
WATCH: Full replay of Navy vs. RAF in T20 Cricket opener