| Assistant Chief of the Naval Staff | |
|---|---|
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| Ministry of Defence | |
| Member of | Admiralty Board, Navy Board, Navy Command |
| Reports to | Second Sea Lord and Deputy Chief of Naval Staff and Fleet Commander |
| Nominator | Secretary of State for Defence |
| Appointer | Prime Minister Subject to formal approval by the King-in-Council |
| Term length | Not fixed (typically 1–3 years) |
| Inaugural holder | Alexander Ludovic Duff |
| Formation | 1917 |
The Assistant Chief of the Naval Staff (A.C.N.S.) is a senior appointment in the Royal Navy usually a two-star rank and has a NATO ranking code of OF-7.